Autonomic Nervous System - Updated Pwr Point Exam 1.pptx PDF

Sympathetic nervous system Autono Activated under stress Fight-or-flight response Readies the body for an mic immediate response to a potential threat Parasympathetic nervous system Nervous Activated un...

Sympathetic nervous system Autono Activated under stress Fight-or-flight response Readies the body for an mic immediate response to a potential threat Parasympathetic nervous system Nervous Activated under nonstressful conditions System Rest-and-digest response Digestive processes promoted; heart rate and blood pressure decline Autonomic Nervous System: Structure and Function of Autonomic Synapses Primary neurotransmitters of the autonomic nervous system Acetylcholine (A c h) Neurotransmitter of parasympathetic nervous system Norepinephrine (N E) Neurotransmitter of sympathetic nervous system Autonomic Nervous System: Released by cholinergic nerves Two types of cholinergic receptors Acetylcholi Nicotinic receptors (named this because nicotine binds to ne and these receptors) Muscarinic receptors Cholinergi (named this because muscarine from poisonous c mushrooms binds to these receptors) Transmissi on  Prototype Drug: Bethanechol Review all sections: Prototype PG 135 Therapeutic Class: Nonobstructive urinary retention drug Pharmacologic Class: Muscarinic cholinergic receptor drug Actions and Uses Bethanechol is a direct-acting cholinergic agonist that interacts with muscarinic receptors to cause actions typical of parasympathetic stimulation. Its effects are most noted in the digestive and urinary tracts, where it stimulates smooth-muscle contraction. These actions are useful in increasing smooth-muscle tone and muscular contractions in the G I tract following general anesthesia. In addition, it is used to treat nonobstructive urinary retention in patients with atony (lack of muscle tone) of the bladder. Although poorly absorbed from the G I tract, it may be administered orally or by subcutaneous injection. Treatment of Overdose: Atropine sulfate is a specific antidote. Subcutaneous injection of atropine is preferred except in emergencies when the I V route may be used. Prototype Drug Physostigmine Review all sections: Prototype PG 138 Therapeutic Class: Antidote for anticholinergic toxicity Pharmacologic Class: Acetylcholinesterase inhibitor Actions and Uses Physostigmine is an indirect-acting parasympathomimetic that inhibits the destruction of ACh by AChE. Its effects occur at the neuromuscular junction and at central and peripheral locations where ACh is the neurotransmitter. It reverses toxic and life-threatening delirium caused by atropine, diphenhydramine, dimenhydrinate, Atropa belladonna (deadly nightshade), or Jimson weed. Physostigmine is usually administered as an injectable solution, intramuscular (I M) or I V, although it is not intended as a first line medication for anticholinergic toxicity or Parkinson’s disease.  Medical Emergency Overdose of Acetylcholinesterase Inhibitor (Physostigmine) Intense Parasympathetic Stimulation Hypersalivation Small Pupils CHOLINERG Muscle Twitching Sweating IC CRISIS Muscle Weakness Difficulty Breathing ANTIDOTE IS ATROPINE!  Drugs that inhibit the action of the neurotransmitter A C h at cholinergic synapses Suppression of parasympathetic Anticholiner division induces fight-or-flight gics: symptoms Uses are predictable extension of Cholinergic- parasympathetic-blocking effects Effects include Blocking Pupil dilation (mydriasis) Drugs Increasing heart rate Drying glandular secretions Relaxing bronchi (asthma) Prototype Drug Atropine Review all sections: Prototype PG 139 Others: Benztropine (Parkinson’s) Dicyclomine (IBS) TABLE 12.2 Therapeutic Class: Drug for treatment of bradycardia, antidote for anticholinesterase poisoning Pharmacologic Class: Anticholinergic, muscarinic receptor blocker Actions and Uses By occupying muscarinic receptors, atropine blocks the parasympathetic actions of A C h and induces symptoms of the fight-or-flight response. Most prominent are increased heart rate, bronchodilation, decreased motility in the G I tract, mydriasis, and decreased secretions from glands. At therapeutic doses, atropine has no effect on nicotinic receptors in ganglia or on skeletal muscle. Adverse Effects The side effects of atropine limit its usefulness and are predictable extensions of its autonomic actions. Expected side effects include dry mouth, constipation, urinary retention, and an increased heart rate. Initial CNS excitement may progress to delirium and even coma. Decorative image Prototype Drug Atropine Actions and Uses (cont ) inued Although atropine has been used for centuries for a variety of indications, its use is limited because of the development of safer and more effective medications. Atropine may be used to treat hypermotility diseases of the G I tract such as irritable bowel syndrome, to suppress secretions during surgical procedures, to increase the heart rate in patients with bradycardia, and to dilate the pupil during eye examinations. Atropine is an antidote used to reverse symptoms of toxicity due to overdose of cholinergic agonists, including organophosphate insecticides and ingestion of mushrooms containing muscarine. Atropine therapy is useful for the treatment of reflexive bradycardia in infants and infantile hypertrophic pyloric stenosis. Decorative image Prototype Drug Atropine Interactions (cont ) inued Treatment of Overdose: Accidental poisoning has occurred in children who eat the colorful, purple berries of the deadly nightshade, mistaking them for cherries. Symptoms of poisoning are those of intense parasympathetic stimulation. Overdose may cause C NS stimulation or depression. A short- acting barbiturate or diazepam (Valium) may be administered to control convulsions. Physostigmine is an antidote for atropine poisoning that quickly reverses the coma caused by large doses of atropine.  Primary neurotransmitter released from postganglionic nerve terminals Class of agents called catecholamines, all involved in neurotransmission Norepinephrine Natural catecholamines: N E, epinephrine (adrenalin), (N E) dopamine Noncatecholamine: structurally different from natural Ephedrine, phenylephrine, and terbutaline  Adrenergic receptors: located on target organs Induce adrenaline like responses Two basic types Norepinephrine Alpha receptors Beta receptors (N E) Then further divided into subtypes REVIEW Illustration 13.1 PG145 (image on next slide)  Also known as sympathomimetics Have clinical applications in the treatment of shock and hypotension Adrenergic Clinical Applications Produce many of the Agonists same responses as the anticholinergics Sympathomimetics may be described chemically as catecholamines or noncatecholamines Adrenergic Agonists (Sympathomimetics) Clinical Applications Alpha recepto 1 r Treatment of nasal congestion or hypotension Causes dilation of the pupil (mydriasis) during ophthalmic examinations Alpha2 recepto r Treatment of hypertension (HTN) through a centrally acting (CNS) mechanism Adrenergic Agonists (4 of 5) Clinical Applications (cont )inued Beta1 receptor Increases Contractility! Treatment of cardiac arrest, heart failure, and shock Beta2 receptor Treatment of chronic obstructive pulmonary disease (COPD), asthma, and preterm labor contractions Beta receptor 3 Treatment of overactive bladder Prototype Drug: Phenylephrine Review all sections: Prototype PG 147 Therapeutic Class: Nasal decongestant; mydriatic drug; antihypotensive Pharmacologic Class: Adrenergic drug (sympathomimetic) Actions and Uses Phenylephrine is a selective alpha- adrenergic agonist that is available in different formulations, including intranasal, ophthalmic, intramuscular (I M), subcutaneous, and intravenous (I V). All its actions and indications are extensions of its sympathetic stimulation. Intranasal Administration: When applied intranasally by spray or drops, phenylephrine reduces nasal congestion by constricting small blood vessels in the nasal mucosa.  Adrenergic Antagonists Also known as adrenergic blockers Inhibit the sympathetic nervous system and produce many of the same rest-and-digest symptoms as the cholinergic agonists Wide therapeutic application Clinical applications Act by directly blocking adrenergic receptors Less commonly known as sympatholytics Alpha blockers Are used for their effects on vascular smooth muscle Cause vasodilation Adverse effect – orthostatic hypotension, reflex tachycardia, nasal congestion and impotance Prototype Drug: Prazosin Review all sections: Prototype PG 150 Therapeutic Class: Antihypertensive Pharmacologic Class: Adrenergic-blocking drug Actions and Uses Prazosin is a selective alpha1-adrenergic antagonist that competes with norepinephrine at its receptors on vascular smooth muscle in arterioles and veins. Its major action is a rapid decrease in peripheral resistance that reduces blood pressure. It has little effect on cardiac output or heart rate, and it causes less reflex tachycardia than some other drugs in this class. Tolerance to prazosin’s antihypertensive effect may occur. Its most common use is in combination with other drugs, such as beta blockers or diuretics, in the pharmacotherapy of hypertension. Prazosin has a short half-life and is often taken two or three times per day. Seizures Antiepileptic Seizure Convulsions drugs (A E D s) disturbance of involuntary, violent address signs and electrical activity in spasms of the large symptoms of the brain that may skeletal muscles of epilepsy affect the face, neck, arms, consciousness, and legs motor activity, and sensation Causes of Seizures Causes of seizures Triggers strobe or flickering lights occurrence of small fluid and electrolyte imbalances Idiopathic – no specific cause can be identified 50% of seizures Neurologic problems Medication for mood disorders, psychoses Local anaesthesia in high doses Drug abuse and withdrawal Causes of Seizures Causes of seizures (continued) Fever Metabolic disorders Neoplastic disease Trauma Vascular disease Pregnancy and Epilepsy Several antiseizure drugs decrease effectiveness of oral contraceptives Most antiseizure drugs are pregnancy category D Eclampsia Severe hypertensive disorder of pregnancy, characterized by seizures, coma, and perinatal mortality  Five general mechanisms An increase in the activity of gamma- aminobutyric acid (G A B A) in the brain (increasing influx of chloride ions) Mechanis Inhibition of the influx of sodium into ms of neurons Action of Inhibition of the influx of calcium into Antiseizur neurons e Drugs Correcting neurotransmitter imbalance Blocking of glutamate receptors in the brain Drugs That Potentiate G A B A Action G A B A – gamma-aminobutyric acid Primary inhibitory neurotransmitter in the brain Predominant effect of G A B A potentiation is C N S depression Drugs Barbiturates Benzodiazepines Miscellaneous drugs  Intensify the effect of G A B A in the brain and generally depress Treating the firing of C N S neurons Seizures with Newer and safer drugs have Barbiturate replaced barbiturates as first-line drugs s (1 of 2) Low margin for safety High potential for dependence Treating Seizures with Barbiturates (2 of 2) Phenobarbital Able to suppress abnormal neuronal discharge without causing major sedation Inexpensive and long lasting Low incident of adverse effects Barbiturates effective against all seizure types except absence seizures Status Epilepticus (S E) – continuous seizure lasting longer than 30 minutes or two or more seizures without full recovery of consciousness Prototype Drug: Phenobarbital Review all sections: Prototype PG 210 Therapeutic Class: Antiseizure drug; sedative Pharmacologic Class: GABA A receptor Barbiturate; agonist Actions and Uses Phenobarbital is a long-acting barbiturate used for the management of a variety of seizures. It is also used to promote sleep. Phenobarbital should not be used for pain relief because it may increase a patient’s sensitivity to pain. Phenobarbital acts biochemically by enhancing the action of the GABA neurotransmitter, which is responsible for suppressing abnormal neuronal discharges that can cause epilepsy. Prototype Drug: Phenobarbital Administration Alerts Parenteral phenobarbital is a soft-tissue irritant. Intramuscular (IM) injections may produce a local inflammatory reaction. IV administration is rarely used because extravasation may produce tissue necrosis. Abrupt discontinuation may increase seizure frequency. This drug is teratogenic in humans. It should only be used during pregnancy if the potential benefits to the mother clearly justify the potential risks to the fetus and neonate. Breastfeeding may cause sedation in the neonate and is not advised. Nursing Clinical Judgement: Pharmacotherapy of Antiseizure Drugs Take Action Patient Teaching: Medication Adverse Effects Continue to monitor vital signs, mental status, coordination, and balance periodically. Lifespan: Ensure patient safety, being particularly cautious with older adults who are at increased risk for falls. Antiseizure drugs may cause drowsiness and dizziness, hypotension, or impaired mental and physical abilities, increasing the risk of falls and injury. Prototype Drug: Diazepam Review all sections: Prototype PG 211 Therapeutic Class: Antiseizure drug Pharmacologic Class: GABA A receptor Benzodiazepine; agonist Actions and Uses In antiseizure therapy, the primary indication for diazepam is status epilepticus. FIRST LINE TREATMENT FOR ACTIVE SEIZURE! It may also be used to prevent seizures in patients who have received toxic substances or during the acute phase of alcohol or benzodiazepine withdrawal. Diazepam binds to the GABA receptor–chloride channels throughout the C NS. It produces its effects by suppressing neuronal activity in the limbic system and subsequent impulses that might be transmitted to the reticular activating system. When used orally, maximum therapeutic effects may take from 1 to 2 weeks. Tolerance may develop after about 4 weeks. When given IV, effects occur in minutes and its anticonvulsant effects last about 20 minutes. Prototype Drug: Diazepam Administration Alerts When administering IV, monitor respirations every 5 to 15 minutes. Have airway and resuscitative equipment accessible. This drug causes fetal harm in pregnant laboratory animals and neonates may experience withdrawal symptoms. It should only be used during pregnancy if the potential benefits to the mother clearly justify the potential risks to the fetus and neonate. Use caution if breastfeeding. Pharmacokinetic s Onset Peak Duration 30–60 min P O; 1–2 h PO; 15 min I M; 2–3 h PO; 15–30 min I V 1–5 min I V 15–60 min I V Prototype Drug: Diazepam Adverse Effects Because of tolerance and dependency, use of diazepam is reserved for short-term seizure control or for status epilepticus. When given IV, hypotension, muscular weakness, tachycardia, drowsiness, and respiratory depression are common. Contraindications: When administered in injectable form, this medication should be avoided under the following conditions: shock, coma, depressed vital signs, obstetrical patients, and infants less than 30 days of age. In tablet form, the medication should not be administered to infants less than 6 months of age, to patients with acute narrow-angle glaucoma or untreated open- angle glaucoma, or within 14 days of monoamine oxidase inhibitor (MAOI) therapy. AVOID USING WITH ALCOHOL /ALCOHOL ABUSE Prototype Drug: Diazepam Interactions Drug–Drug: Diazepam should not be taken with alcohol or other CNS depressants because of combined sedation effects. Other drug interactions include cimetidine, oral contraceptives, valproic acid, and metoprolol, which potentiate diazepam’s action; and levodopa and barbiturates, which decrease diazepam’s action. Diazepam increases the levels of phenytoin in the bloodstream and may cause phenytoin toxicity. Herbal/Food: Kava and chamomile may cause an increased drug effect. Treatment of Overdose: If an overdose occurs, administer flumazenil (Romazicon), a specific benzodiazepine receptor antagonist to reverse CNS depression.  Treating Seizures Sodium channels are not blocked but desensitized with Not desensitized directly but affect the threshold of Hydantoin neuron firing or interfere with the transduction of glutamine and Related Phenytoin Drugs Broad spectrum drug useful for treating all types of seizures except absence seizures No abuse potential or C N S depression associated with barbiturates Prototype Drug: Phenytoin Review all sections: Prototype PG 213 Therapeutic Class: Antiseizure drug; antidysrhythmic Pharmacologic Class: Hydantoin; sodium influx–suppressing drug Actions and Uses Phenytoin acts by desensitizing sodium channels in the C NS, preventing the spread of abnormal electrical charges in the brain that produce seizures. It is effective against most types of seizures except absence seizures. Phenytoin has antidysrhythmic activity similar to that of lidocaine (see Chapter 30). Phenytoin (Phenytek) is an extended-release form of the drug that allows once-daily dosing. Patients vary significantly in their ability to metabolize phenytoin; therefore, dosages are highly individualized. Because of the very narrow range between a therapeutic dose and a toxic dose, patients must be carefully monitored. Phenytoin and fosphenytoin are first-line drugs in the treatment of status epilepticus. Decorative image Prototype Drug: Phenytoin (Dilantin) Administration Alerts Always prime or flush IV lines with saline before hanging phenytoin as a piggyback because traces of dextrose solution in an existing main IV or piggyback line can cause microscopic precipitate formation, which become emboli if infused. Use an IV line with filter when infusing this drug. Phenytoin injectable is a soft-tissue irritant that causes local tissue damage following extravasation. To reduce the risk of soft-tissue damage, do not give IM; inject into a large vein or via a central venous catheter. This drug is a known teratogen and is contraindicated during pregnancy. Phenytoin is secreted in breast milk and has the potential to cause adverse effects on the breastfed neonate Treating Seizures with Succinimides Succinimides Drugs small group of A E D s Ethosuximide that delay entry of Lamotrigine calcium into neurons Zonisamide by blocking low- threshold calcium channels raise the seizure threshold and keep neurons from firing too quickly; thus, they suppress abnormal foci Generally effective against absence seizures Prototype Drug Ethosuximide Review all sections: Prototype PG 215 Therapeutic Class: Antiseizure drug Pharmacologic Class: Succinimide Actions and Uses Ethosuximide is a preferred drug for managing absence seizures. It depresses the activity of neurons in the motor cortex by elevating the neuronal threshold. It is usually ineffective against psychomotor or tonic–clonic seizures; however, it may be given in combination with other medications that better treat these conditions. It is available in tablet and flavored-syrup formulations. Prototype Drug: Valproic Acid Review all sections: Prototype PG 214 Therapeutic Class: Antiseizure drug Pharmacologic Class: Valproate Actions and Uses Valproic acid is a first-line drug for treating many types of epilepsy. This medication has several formulations, which can cause confusion when studying it. Valproic acid is the delayed-release form of the drug given by the oral route. Valproate sodium is the sodium salt of valproic acid given P O or IV. Divalproex sodium (Depakote E R) is a sustained-release combination of valproic acid and its sodium salt in a 1:1 mixture. It is given PO and is available in an enteric-coated form. Nursing Clinical Judgement: Pharmacotherapy of Antiseizure Drugs PG215 Evaluate Outcomes Medication Effectiveness Assess for desired therapeutic effects (e.g., diminished or absence of seizure activity). Antiseizure drugs may not completely resolve symptoms, but frequency and severity of seizures should be diminished.) Continue periodic monitoring of C BC and liver and kidney function studies. MUST TAPER OFF – DO NOT STOP TAKING ABRUPTLY IF SEIZURE ACTIVITY CONTINUES, SECOND DRUG MAY BE ADDED OR DOSE MAY BE INCREASED Copyright © 2024, 2020, 2017 Pearson Education, Inc. All Rights Reserved  Regional Loss of Sensation Using Local Anesthesia Topical (surface) Infiltration (field Creams, sprays, block) suppositories Direct injection into tissue Drops and lozenges immediate to surgical site Applied to mucous Blocks specific groups of membranes nerves near site Safe, unless absorbed in the systemic system  Regional Loss of Sensation Using Local Anesthesia Nerve Block Spinal Anesthesia Epidural Anesthesia Anesthesia Direct injection into Injected into C S F Injected into tissues that may be Affects large, epidural space of distant from surgical regional areas such spinal canal site as lower abdomen Used most often in Affects nerve and legs labor and delivery bundles supplying surgical area Used to block sensation in a limb or large area of face  Classification of Local Anesthetics Esters Drugs Contain an ester chemical Benzocaine linkage Topical O T C agent Incidence of allergic Procaine reaction is low Benzocaine Cocaine natural ester Tetracaine First widely used Proparacaine anesthetic  Amides Contain amide chemical Classificati linkage on of Local Longer duration of action Anesthetic and fewer side effects than s Drugs esters Lidocaine Articaine Bupivacaine Prototype Drug: Lidocaine Review all sections: Prototype PG 247 Therapeutic Class: Anesthetic (local/topical); antidysrhythmic (class IB) Pharmacologic Class: Sodium channel blocker; amide Actions and Uses Lidocaine, the most frequently used injectable local anesthetic, acts by blocking neuronal pain impulses. It may be injected as a nerve block for spinal and epidural anesthesia. Lidocaine patches may be administered to relieve pain related to postherpetic neuralgia (Lidoderm) or dental procedures (DentiPatch). Zingo (lidocaine hydrochloride monohydrate) is a needle-free intradermal injection system that is indicated for rapid local anesthesia. It works by providing 0.5 m g lidocaine topically. This method is useful for pretreatment in instances such as IV insertions or blood draws. Like other amides, lidocaine acts by blocking sodium channels located within neuronal membranes. Propofol Prototype PG 251 IV Anesthetic Medication that Michael Jackson died from abusing Monitor Respirations Immediate onset of action – rapid emergence Review PIF (Propofol Infusion Syndrome) Severe metabolic acidosis Hyperkalemia  Balanced anesthesia Multiple medications that rapidly induce unconsciousness, cause General muscle relaxation, and maintain deep anesthesia Progressive process/distinct Anestheti stages cs Loss of pain Excitement and hyperactivity Surgical anesthesia When most surgical procedures happen Respiratory and cardiovascular paralysis Pharmacother Opioids Alfentanil (Alfenta), apy with remifentanil (Ultiva), sufentanil (Sufenta) Intravenous Fentanyl (Sublimaze, others) General given with antipsychotic agent to produce neuroleptanalgesia Anesthetics Patients are conscious but insensitive to pain and unconnected with surroundings Premixed combination of the two agents called Innovar  Therapeutic gases and volatile liquids Pharmacother apy with Prevent flow of sodium into Inhaled General neurons in C N S, delay nerve Anesthetics impulses, produce reduction in neural activity Exact mechanism not known but may be related to anti seizure drugs Prototype Drug: Nitrous Oxide Review all sections: Prototype PG 252 Therapeutic Class: Inhalation gaseous drug Pharmacologic Class: General aesthetic Actions and Uses The main action of nitrous oxide is analgesia caused by suppression of pain mechanisms in the CN S. This agent has a low potency and does not produce complete loss of consciousness or profound relaxation of skeletal muscle. Because nitrous oxide does not induce surgical anesthesia (stage 3), it is commonly combined with other surgical anesthetic agents. Nitrous oxide is ideal for short surgical or dental procedures because the patient remains conscious and can follow instructions while experiencing full analgesia. Prototype Drug: Isoflurane Review all sections: Prototype PG 252 Therapeutic Class: Inhaled general anesthetic Pharmacologic Class: GABA and glutamate receptor agonist Actions and Uses Isoflurane produces a potent level of surgical anesthesia that is rapid in onset. It provides the patient with smooth induction with a low degree of metabolism by the body. This drug provides excellent muscle relaxation and may be used off- label as adjuvant therapy in the treatment of status asthmaticus. Isoflurane with oxygen or with an oxygen and nitrous oxide mixture may be used. Isoflurane does not sensitize the myocardium for dysrhythmias, and it produces fewer cardiovascular effects than other general anesthetics. Prototype Drug: Succinylcholine Review all sections: Prototype PG 255 Therapeutic Class: Skeletal muscle paralytic drug; neuromuscular blocker Pharmacologic Class: Depolarizing blocker; acetylcholine receptor blocking drug Actions and Uses Like the natural neurotransmitter acetylcholine, succinylcholine acts on cholinergic receptor sites at neuromuscular junctions. At first, depolarization occurs, and skeletal muscles contract. After repeated contractions, however, the membrane is unable to repolarize as long as the drug stays attached to the receptor. Effects are first noted as muscle weakness and muscle spasms.  Most common degenerative C N S disease Characteris Progressive loss of dopamine tics of Symptoms Parkinson Tremors Muscle rigidity Disease Bradykinesia (difficulty chewing, swallowing, speaking) Postural instability Affective flattening Characteristics of Parkinson Disease Primarily affects muscle Patients often experience movement other health issues Anxiety, depression Sleep disturbances Dementia Autonomic nervous system disturbances (e.g., difficulty urinating) Prototype Drug: Levodopa, Carbidopa, and Entacapone Review all sections: Prototype PG 264 Therapeutic Class: Antiparkinson drug Pharmacologic Class: Dopamine precursor; dopamine-enhancing drug combination Actions and Uses Stalevo restores the neurotransmitter dopamine in extrapyramidal areas of the brain, thus relieving some Parkinson symptoms, especially tremor, bradykinesia, gait, and muscle rigidity. To increase its effect, levodopa is combined with two other drugs, carbidopa and entacapone, which prevent its enzymatic breakdown. Several months may be needed to achieve maximum therapeutic effects. Prototype Drug: Levodopa, Carbidopa, and Entacapone Adverse Effects Most side effects of Stalevo are due to levodopa and include uncontrolled and purposeless movements (such as extending the fingers and shrugging the shoulders), loss of appetite, nausea, and vomiting. Muscle twitching and spasmodic winking are early signs of toxicity. Orthostatic hypotension is common in some patients. The drug should be discontinued gradually because abrupt withdrawal can produce acute Parkinson-like symptoms. Psychosis develops in up to 20% of patients taking levodopa, and drug therapy with an antipsychotic, such as clozapine (Clozaril), may be necessary to control hallucinations and paranoid feelings.  Centrally acting Treating Block acetylcholine Inhibit overactivity in brain Parkinson Not as effective as dopaminergics Disease with Used in early stages of P D therapy Anticholine Most beneficial when primary symptom is tremor rgic Drugs Prominent autonomic effects Dry mouth, blurred vision, tachycardia, urinary retention, constipation Prototype Drug: Benztropine Review all sections: Prototype PG 265 Therapeutic Class: Antiparkinson drug Pharmacologic Class: Centrally acting cholinergic receptor blocker Actions and Uses Benztropine acts by blocking excess cholinergic stimulation of neurons in the corpus striatum. It is used for relief of Parkinson-like symptoms and for the treatment of E PS brought on by antipsychotic pharmacotherapy. This medication suppresses tremors but is not effective at relieving tardive dyskinesia. Prototype Drug: Benztropine Adverse Effects As expected from its autonomic action, benztropine can cause typical anticholinergic side effects such as dry mouth, constipation, and tachycardia. Adverse general effects include sedation, drowsiness, dizziness, restlessness, irritability, nervousness, and insomnia. Contraindications: Contraindications include narrow-angle glaucoma, myasthenia gravis, blockage of the urinary tract, severe dry mouth, hiatal hernia, severe constipation, enlarged prostate, and liver disease.  Second most common degenerative disease of C N S Progressive loss of brain function Characteris Memory loss, confusion, dementia tics of 50% of the population over 85 may be affected by A D Alzheimer A D responsible for 70% of all dementia Disease Progressive loss of brain function Memory loss, confusion, inability to think or communicate effectively Affects memory, cognitive function, and behavior  Known causes of dementia Multiple cerebral infarcts, severe infections and toxins Characteris Possible causes for A D tics of Genetic factors (10% of cases) Alzheimer Chronic inflammation, excess free radicals Disease Environmental factors Immunologic factors Nutritional factors Viruses Characteristics of Alzheimer Disease Structural damage of the brain Consists of Amyloid plaques Neurofibrillary tangles Changes found during autopsies Characteristics of Alzheimer Disease Symptoms of A D Impaired memory and judgment Confusion and disorientation Inability to recognize family and friends Aggressive behavior Depression Psychoses, including paranoia and delusions Anxiety Treating A D with Cholinesterase Inhibitors Goals of Pharmacotherapy Efficacy of drug therapy for Alzheimer Disease Slow memory loss No cure Slow dementia symptoms Intensify effect of acetylcholine at Improve activities of daily living cholinergic receptor Improve behavior Drugs have modest efficacy Improve cognition Ineffective in late stages Prototype Drug: Donepezil Review all sections: Prototype PG 268 Therapeutic Class: Alzheimer disease drug Pharmacologic Class: Cholinesterase inhibitor Actions and Uses Donepezil is an ACh E inhibitor that improves memory in cases of mild to moderate Alzheimer dementia by enhancing the effects of acetylcholine in neurons in the cerebral cortex that have not been damaged. Patients should receive pharmacotherapy for at least 6 months prior to assessing maximum benefits of drug therapy. Improvement in memory may be observed as early as 1 to 4 weeks following medication. The therapeutic effects of donepezil are often short-lived, and the degree of improvement is modest, at best. An advantage of donepezil over other drugs in its class is that its long half-life permits it to be given once daily. Treating A D with Cholinesterase Inhibitors Memantine Adjunct A D Approved for treatment of moderate to Medicines Atypical antipsychotic agents severe A D Anxiolytics Reduces abnormally high levels of Mood stabilizers glutamate GINKO BILOBA (READ PG 264!) May have a protective function in reducing neuronal calcium overload Characteristics of Multiple Sclerosis Inflammatory disorder Progressive causing damage to Mood alterations, Etiology unknown, weakness, visual Possible causes myelin in brain and cognitive deficits and no cure exists disturbances spinal cord Genetic or microbial factors Climate (colder regions) Microscopic pathogens Characteristics of Multiple Sclerosis Signs and Symptoms Fatigue Heat sensitivity Neuropathic pain; spasticity Impaired cognitive ability Disruption of balance and coordination Visual impairment; slurred speech Sexual dysfunction Bowel and bladder symptoms Dizziness; vertigo Treating M S with Disease- Modifying Drugs Disease-modifying drugs used for treatment of relapse-remitting M S and secondary-progressive M S Two categories Interferon beta Glatiramer Synthetic protein that simulates myelin basic protein Reduce symptoms and decrease lesions Treating M S with Disease- Modifying Drugs Interferons TABLE 20.5 Unfavorable side effects Flulike symptoms Anxiety Discomfort at the injection site Hepatotoxicity Caution when taking with chemotherapeutics or bone marrow suppressing drugs Treating M S with Disease- Modifying Drugs Other disease-modifying drugs Fingolimod – reduces the number of circulating lymphocytes Dimethyl fumarate – thought to inhibit immune processes that damage the brain and spinal cord Teriflunomide – previously used for rheumatoid arthritis; must be carefully monitored Dalfampridine – broad spectrum potassium channel blockade Causes Excessive use or local injury to skeletal muscle of Overmedication with antipsychotics Epilepsy Muscle Hypocalcemia Dehydration Spasms Neurologic disorders Pharmacologic Treatment of Muscle Spasticity Combination of: Analgesics Anti-inflammatory agents Centrally acting skeletal muscle relaxants REVIEW TABLE 21.1 – Centrally Acting Drugs that Relax Skeletal Muscle REVIEW TABLE 21.4 – NEUROMUSCULAR BLOCKING DRUGS (Rocuronium, Methocarbamol, etc.)  Prototype Drug: Cyclobenzaprine Review all sections: Prototype PG 280 Therapeutic Class: Centrally acting skeletal muscle relaxant Pharmacologic Class: Catecholamine reuptake inhibitor Actions and Uses: Cyclobenzaprine relieves muscle spasms of local origin without interfering with general muscle function. This drug acts by depressing motor activity primarily in the brainstem; limited effects also occur in the spinal cord. Cyclobenzaprine increases circulating levels of norepinephrine, blocking presynaptic uptake. Its mechanism of action is similar to that of tricyclic antidepressants (see Chapter 16). The drug causes muscle relaxation in cases of acute muscle spasticity, but it is not effective in cases of C P or diseases of the brain and spinal cord. This medication is structurally similar to amitriptyline; thus, the same adverse drug reactions should be expected, and precautions taken. Cyclobenzaprine is meant to provide therapy for only 2 to 3 weeks. Prototype Drug: Dantrolene Sodium Review all sections: Prototype PG 283 Therapeutic Class: Skeletal muscle relaxant Pharmacologic Class: Direct-acting antispasmodic; calcium release blocker Actions and Uses: Dantrolene is often used for spasticity, especially for spasms of the head and neck. It directly relaxes muscle spasms by interfering with the release of calcium ions from storage areas inside skeletal muscle cells. It does not affect cardiac or smooth muscle. Dantrolene is especially useful for muscle spasms when they occur after spinal cord injury or stroke and in cases of CP or MS. Occasionally, it is useful for the treatment of muscle pain after heavy exercise. An I V form (Revonto) is a preferred drug for the treatment of malignant hyperthermia. Neuromuscular Blockers TABLE 21.4 –REVIEW TABLE! Used to relax muscles during surgical procedures Bind to nicotinic receptors located on surface of skeletal muscle fibers: Interfere with binding of acetylcholine Patients can still feel pain: For surgical procedures, anesthetic agents also used Shock Inadequate blood flow to meet body’s needs Considered medical emergency Can lead to irreversible organ damage and death Collection of nonspecific signs and symptoms Affects the nervous, renal, cardiovascular systems  Most types have symptoms in common Pallor; cold, clammy skin Feeling of sickness and weakness Restlessness, anxiety, confusion, depression, apathy Shock B P low, heart rate may be rapid with weak pulse Breathing usually rapid and shallow Unconsciousness Thirst (avoid giving them unless able to swallow)  Cardiovascular system fails to send enough blood to vital organs Heart and brain affected early Low B P and diminished Shock cardiac output Heart rate is rapid and weak Breathing is shallow and rapid  Symptoms and Types of Shock Hypovolemic shock: Neurogenic shock: from Cardiogenic shock: from Anaphylactic shock: from loss of blood volume vasodilation due to failure of heart to pump from severe reaction to changes in autonomic sufficient blood an allergen nervous system  Septic shock Multiple-organ dysfunction Result of pathogenic Symptoms organisms in blood and Types of Causes vasodilation and changes in permeability of Shock capillaries Often precursor to acute respiratory distress syndrome (A R D S) and disseminated intravascular coagulation (D I C)  Administer oxygen at 15 L/minute via a nonrebreather Initial mask Treatme Monitor level of consciousness nt Prioritie Keep patient warm and quiet s Offer psychological support Pharmacotherapy Treatment of Shock I V Fluids For hypovolemic shock Fluid replacement for Blood, blood products, colloids, crystalloids Replace plasma volume and supply red blood cells Components: Whole blood, plasma protein fraction Fresh-frozen plasma, packed red blood cells Pharmacotherapy Treatment of Shock I V Fluids (continued) Colloid Agents Examples of blood colloids Normal human serum albumin, plasma protein fraction, serum globulins Examples of nonblood- product colloids Dextran (40, 70, and high–molecular weight) and hetastarch Pharmacotherapy Treatment of Shock I V Fluids (continued) Crystalloids Intravenous solutions that contain electrolytes Concentrations resembling those of plasma Mechanism of action: Can readily leave blood and enter cells Prototype Drug: Normal Serum Albumin Therapeutic Class: Fluid replacement drug Pharmacologic Class: Blood product, colloid Actions and Uses Normal serum albumin is a protein extracted from whole blood, plasma, or placental human plasma. Albumin naturally comprises about 60% of all blood proteins. Its normal functions are to maintain plasma osmotic pressure and to shuttle certain substances through the blood, including fatty acids, certain hormones, and a substantial number of drug molecules. After extraction from blood or plasma, albumin is sterilized to remove possible contamination by pathogens. Plasma protein fraction (Plasmanate) is an albumin product that contains 83% albumin and 17% plasma globulins. Albumin is classified as both a blood product and a colloid. Prototype Drug: Normal Serum Albumin Actions and Uses (cont ) inued Administered I V, albumin increases the osmotic pressure of the blood and causes fluid to move from the tissues to the general circulation. It is used to restore plasma volume in hypovolemic shock or to restore blood proteins in patients with hypoproteinemia, which frequently occurs in patients with hepatic cirrhosis. It has an immediate onset of action and is available in concentrations of 5% and 25%. Pharmacotherapy Treatment of Shock Vasoconstrictors (Vasopressors) For maintaining B P Administered via infusion pump Discontinued when patient becomes stable Prototype Drug: Norepinephrine Review all sections: Prototype PG 400 Therapeutic Class: Drug for shock Pharmacologic Class: Nonselective adrenergic agonist: vasopressor Actions and Uses Norepinephrine is a sympathomimetic that acts directly on alpha- adrenergic receptors in vascular smooth muscle to immediately raise blood pressure. To a lesser degree, it also stimulates beta1-receptors in the heart, thus producing a positive inotropic response that may increase cardiac output. Its primary indications are acute shock and cardiac arrest. Norepinephrine is the vasopressor of choice for septic shock because it has been shown to decrease mortality. It is given by the IV route and has a duration of only 1 to 2 minutes after the infusion is terminated. PRIORITY ASSESSMENT: LOC & BP Prototype Drug: Norepinephrine Administration Alerts Start an infusion only after ensuring the patency of the I V. Monitor the flow rate continuously. If extravasation occurs, administer phentolamine to the area of infiltration as soon as possible. Do not abruptly discontinue infusion. This drug causes fetal harm in pregnant laboratory animals; however, its effects on human pregnancy and lactation are not known. Prototype Drug: Norepinephrine Interactions Drug–Drug: Alpha and beta blockers may antagonize the drug’s vasopressor effects. Conversely, ergot alkaloids and tricyclic antidepressants may potentiate vasopressor effects. Use with M AOIs can lead to acute hypertensive crisis. Herbal/Food: Unknown Treatment of Overdose: Discontinuing the infusion usually results in a rapid reversal of adverse effects, such as hypertension. Religious Considerations: Vasopressors can be utilized in place of blood/blood products to raise BP for those who refuse blood products due to religious beliefs. Copyright © 2024, 2020, 2017 Pearson Education, Inc. All Rights Reserved Pharmacotherapy Treatment of Shock Ionotropic Drugs Also called cardiotonic drugs Reversal of cardiac symptoms of shock Prototype Drug: Dopamine Review all sections: Prototype PG 401 Therapeutic Class: Drug for shock Pharmacologic Class: Nonselective adrenergic agonist; inotropic drug Actions and Uses Dopamine is the immediate metabolic precursor to norepinephrine. Although dopamine is classified as a sympathomimetic, its mechanism of action is dependent on the dose. At low doses, the drug selectively stimulates dopaminergic receptors, especially in the kidneys, leading to vasodilation and an increased blood flow through the kidneys. This makes dopamine of particular value in treating hypovolemic and cardiogenic shock. At higher doses, dopamine stimulates beta1- adrenergic receptors, causing the heart to beat more forcefully and increasing cardiac output. Another beneficial effect of dopamine when given in higher doses is its ability to stimulate alpha-adrenergic receptors, thus causing Prototype Drug: Dopamine Adverse Effects Because of its profound effects on the cardiovascular system, patients must be continuously monitored for signs of dysrhythmias and hypertension. Adverse effects are normally self-limiting because of the short half-life of the drug. Dopamine is a vesicant drug that can cause severe, irreversible skin and soft tissue damage if the drug infiltrates. Black Box Warning: Following extravasation, the affected area should be infiltrated immediately with 5 m g to 10 mg of phentolamine, an adrenergic blocker. Contraindications: Dopamine is contraindicated in patients with pheochromocytoma or ventricular fibrillation. Anaphylaxis Potentially fatal hypersensitivity response to allergen Body responds by releasing massive amounts of histamine Signs and Symptoms Itching, hives, periorbital edema (swelling around the eye) Tightness in throat or chest, nonproductive cough, wheezing, hoarse voice Rapid fall in blood pressure, difficulty breathing Anaphylaxis Other signs of shock Palpitations, chest pain, nausea, vomiting Sweating, weakness, dizziness, confusion Blurred vision, headache, anxiety Sense of impending doom May be caused by Penicillin, cephalosporins, sulfonamides Nonsteroidal anti-inflammatory drugs (N S A I D s) A C E inhibitors Opioid analgesics and iodine-based contrast media Iodine-based contrast media (shellfish) Pharmacotherapy of Anaphylaxis Treatment Prevention by knowledge/avoidance of triggers, carrying EpiPen or Auvi-Q Sympathomimetics, antihistamines, glucocorticoids Therapy is symptomatic To support cardiovascular system To prevent further hyperreaction of immune system Pharmacotherapy of Anaphylaxis Treatment (continued) Give oxygen immediately Antihistamine—Prevents release of histamine Bronchodilator—Relieves shortness of breath (use short acting albuterol) Corticosteroids—Suppress inflammation Prototype Drug Epinephrine Review all sections: Prototype PG 404 Therapeutic Class: Drug for anaphylaxis and shock Pharmacologic Class: Nonselective adrenergic agonist; vasopressor Actions and Uses Subcutaneous or IV epinephrine is a preferred drug for anaphylaxis because it can reverse many of the distressing symptoms within minutes. Epinephrine is a nonselective adrenergic agonist, stimulating both alpha- and beta-adrenergic receptors. Almost immediately after injection, blood pressure rises due to stimulation of alpha1 receptors. Activation of beta2 receptors in the bronchi opens the airways and relieves the patient’s shortness of breath. Cardiac output increases due to stimulation of beta1 receptors in the heart. In addition to the subcutaneous and I M routes, topical, inhalation, and ophthalmic preparations are available. The intracardiac route is used for cardiopulmonary resuscitation under extreme conditions, usually during open cardiac massage, or when no other route is possible. Prototype Drug Epinephrine Adverse Effects The most common adverse effects of epinephrine are nervousness, tremors, palpitations, tachycardia, dizziness, headache, and stinging or burning at the site of application. When administered parenterally, hypertension and dysrhythmias may occur rapidly; therefore, the patient should be monitored carefully following injection. Contraindications: In life-threatening conditions such as anaphylaxis, there are no absolute contraindications for the use of epinephrine. The drug must be used with caution, however, in patients with dysrhythmias, cerebrovascular insufficiency, hyperthyroidism, narrow-angle glaucoma, or HT N because epinephrine may worsen these conditions. The drug should be used with caution in patients with coronary artery disease because intense angina symptoms may result. Nursing Clinical Judgement: Pharmacotherapy for Shock PAGE 401 Take Action MONITOR BP MONITOR LOC MONITOR O2 SAT ADMINISTER VASOPRESSOR COMFORT PATIENT