Drugs Affecting Autonomic and Central Nervous System PDF

Drugs Affecting Autonomic and Central Nervous System  Autonomic Nervous System – controls most tissue function. This nervous system helps control blood pressure, gastrointestinal secretion and motility, urinary bladder function, sweating, and body temperature. ...

Drugs Affecting Autonomic and Central Nervous System  Autonomic Nervous System – controls most tissue function. This nervous system helps control blood pressure, gastrointestinal secretion and motility, urinary bladder function, sweating, and body temperature.  Central Nervous System – make up of brain and spinal cord. The CNS receive signals from sensory receptors such as vision, pressure, pain, cold warmth, touch or smell throughout the body that are transmitted to the spinal cord and brain by the way of afferent. The CNS processes these signals and controls body response by sending signals through efferent nerves, which leaves the CNS to carry impulses to other parts of the body.  Drugs Classifications: o Adrenergic Agents o Alpha and Beta Adrenergic o Cholinergic Agent o Anticholinergic Agent o Pain Management – Analgesic o Seizure Disorders – Anticonvulsant  Actions of Autonomic Nerve Impulses on Specific Tissues Body tissue/organ Receptor Type Adrenergic Receptors Cholinergic Receptors (Sympathetic (Parasympathetic response) response) Eye Alpha; Beta1 and Beta2 Dilate Constrict (smooth muscles) Lungs (smooth Beta2 Dilate Constrict muscle) Heart Beta 1 Increase heart rate, Decrease heart rate force of contraction Blood vessels Alpha and Beta2 Constrict Dilates Gastrointestinal Alpha, Beta 1 and 2 Relaxes Increase peristalsis smooth muscles Bladder Beta Relaxes Constricts bladder bladder muscle Uterus Beta2 Relaxes uterine muscle DRUG CLASSIFICATION: Adrenergic Agents ACTIONS  drugs that stimulate the sympathetic nervous system  Adrenergic receptor, otherwise known as adreno-receptor, are classified as either alpha or beta receptors.  They act on one or more receptor sites located in the cells of muscles such as the heart, bronchioles, GI, urinary bladder and ciliary muscles of the eye.  There are 4 main receptors: alpha1, alpha 2, beta1, beta2   Alpha adrenergic receptors are located in the vascular tissues of muscles o When alpha1-receptors are stimulated smooth muscle, the arterioles and venules constrict, increasing blood return to the heart. o When alpha2-receptors are stimulated the mixed smooth muscle, it inhibits the release norepinephrine, leading to decrease in vasoconstriction  Beta adrenergic receptors o The beta1-receptors are located primarily in the heart. Its stimulation increases myocardial contractility and heart rate o The beta2-receptors are found mostly in the smooth muscles of the lungs, and its stimulation causes (1) relaxation of smooth muscles of the lungs, (2) AN INCREASE IN BLOOD FLOW TO THE SKELETAL MUSCLES, (3) relaxation of the uterine muscle. USES Generic Name Adrenergic Action Clinical Uses Receptor Ephedrine Alpha, Beta Bronchodilator, Nasal Decongestant, Vasoconstriction hypotension Epinephrine Alpha, Beta Allergic reactions, Anaphylaxis, cardiac vasoconstrictor, arrest, topical bronchodilator, vasoconstriction cardiac stimulant Metaraminol and Alpha1 Vasoconstriction Shock and norepinephrine hypotension Dobutamine Beta 1 Cardiac Stimulant Inotropic agent Albuterol Beta 2 Bronchodilator Asthma and EMphysema Terbutaline Beta 2 Bronchodilator and Emphysema, asthma uterine relaxant and premature labor Special Precautions  Patients who are potentially more sensitive to adrenergic agents are those with impaired hepatic function, thyroid disease, hypertension and heart disease.  Patients with diabetes mellitus may also have increased frequency of episodes of hyperglycemia. DRUG CLASSIFICATION: Alpha and Beta Adrenergic Blocking Agents ACTIONS Drugs that block the effects of adrenergic neurotransmitters They act as antagonists to adrenergic agonists by blocking the alpha and beta receptor sites. Beta blockers subdivided into  Nonselective Beta antagonist – have an equal affinity for Beta1 and Beta 2 receptors and inhibit both. Example: Propranolol, Nadolol, Pindolol  Selective Beta Antagonist – exhibit action against the heart’s beta 1 receptor and do not readily affect the Beta 2 receptors of the bronchi. Example: Metoprolol, Atenolol and Esmolol USES Generic Name Beta blockers Subdivided Clinical Uses Propanolol Nonselective beta antagonist Dysrrhythmias, hypertension, angina pectoris, myocardial infarction, migraine, tremor Nadolol Nonselective beta antagonist Angina pectoris, hypertension Pindolol Nonselective beta antagonist Hypertension  Metoprolol selective beta antagonist Hypertension, Myocardial Infarction, angina pectoris, heart failure Atenolol selective beta antagonist Hypertension, angina pectoris, after myocardial infarction Esmolol selective beta antagonist Supraventricular tachycardia, hypertension Special Precautions  Beta Blockers should be used with caution in patients with diabetes and those susceptible to hypoglycemia.  Beta blockers further induce the hypoglycemic effects of insulin and reduce the release of insulin in response to hyperglycemia. DRUG CLASSIFICATION: Cholinergic Agent ACTIONS  Also known as parasympathetic agents, produce similar effect to those of acetylcholine. o Acetylcholine – is a neurotransmitter located at the ganglions and the parasympathetic nerve endings  Drugs that stimulate the PNS because they mimic the parasympathetic neurotransmitter acetylcholine.  Two types of cholinergic receptors: o Muscarinic receptors – stimulates smooth muscles and slow HR o Nicotinic receptors (neuromuscular) which affects the skeletal muscles  Two types of cholinergic drugs o Direct-acting – act on the receptors to activate a tissue response o Indirect acting – inhibit the action of the enzyme cholinesterase by forming a chemical complex, thus permitting acetylcholine to persist and attach to the receptors  The major responses of drugs are to stimulate bladder and GI tone, miosis of the eyes which reduces intraocular pressure, and increase neuromuscular transmission. Other effects include decreased HR and BP and increased salivary, GI secretions USES Generic Name Clinical Uses Bethanecol chloride (Urecholine) used to increase urination Metoclopramide (Reglan) Used to treat GERD DRUG CLASSIFICATION: Anticholinergic Agent ACTIONS Drugs that inhibit the actions of acetylcholine in the parasympathetic nervous system. Act by occupying the acetylcholine receptors sites at parasympathetic nerve endings, which prevents the action of acetylcholine. Also known as parasympatholytics, antispasmodics, antimuscarinic agents The major organs affected by the anticholinergic group of drugs are the heart, respiratory tract, GI tract, urinary bladder, eyes, and exocrine glands By blocking the parasympathetic nerves, the SNS dominates. The major responses are decrease in GI motility, decrease salivation, mydriasis of the pupil with increased intraocular pressure in patients with glaucoma, and increase in PR and decrease sweating. USES Generic Name Clinical Uses Atropine Pre-surgery: reduce salivation and bronchial secretions; minimize bradycardia during intubation; treatment of pylorospasm and spastic conditions of the GI tract; treatment of urethral and biliary colic Belladonna Indigestion, peptic ulcer; nocturnal enuresis Dicyclomine Irritable bowel syndrome; infant colic Glycopyrrolate Peptic Ulcer Disease; presurgery; reduce salivation and bronchial secretions; minimize bradycardia during intubation Drugs used for Seizure Disorders  It is estimated that approximately 2.7 million people in the US have active epilepsy, a seizure disorder.  It results from abnormal electric discharges from the cerebral neurons and is characterized by a loss or disturbance of consciousness and usually by a convulsion  50% are considered primary or idiopathic and 50% are considered to be secondary to trauma, brain anoxia, infection, or CVA  International Classification of Seizures  Generalized Seizures – refer to those that affect both hemispheres of the brain, are accompanied by loss of consciousness, and may be into convulsive and nonconvulsive types. Types of Generalized Convulsive Seizures Tonic-Clonic (Grand mal) Seizures – Also known as grand mal; most common form. In the tonic phase, the skeletal muscle contract or tighten in a spasm lasting 3 to 5 seconds. In the clonic phase, there is a dysrhythmic muscular contraction, or jerkiness Atonic or Akinetic Seizures - Head drop; loss of posture, sudden loss of muscle tone Myoclonic Seizures - Isolated clonic contraction or jerks lasting 3 to 10 seconds; may be limited to one limb Types of Generalized Nonconvulsive Seizures Absence - Aka petit mal; brief loss of consciousness lasting less than 10 seconds; fewer than 3 spike waves on the EEG printout; usually occurs in children. Partial Seizures – may be subdivided into simple and complex symptom, types; a change in consciousness occurs with complex seizures. Partial seizures begin in localized are in one hemisphere of the brain.  There are many types of anticonvulsants including hydantoins (phenytoin), long- acting barbiturates, succinimides (ethosuximide), oxazolidones (trimethadione), benzodiazepines (diazepam), carbamazepine, valproate (valproic acid) DRUG CLASSIFICATION: Anticonvulsant ACTIONS Suppress the abnormal electric impulses from the seizure but does not eliminate the cause USES: used to reduce the frequency of seizures Types of Anticonvulsant  Hydantoins  Barbiturates  Benzodiazepines   Succinimides Hydantoins Small effect on sedation and non-addicting Should not be used during pregnancy ACTIONS The first and most common anticonvulsant used is phenytoin Act by inhibiting sodium influx, stabilizing cell membranes, reducing repetitive neural firing, and limiting seizures USES:  Used to control partial seizures and generalized tonic-clonic seizures Barbiturates Less teratogenic Side effects include sedation and tolerance ACTIONS Barbiturates reduce seizure by enhancing the GABA, which is an inhibitory neurotransmitter USES:  Phenobarbital is prescribed to treat partial seizures, grand mal seizures, and acute episodes of status epilepticus, meningitis, and eclampsia Succimides ACTIONS Acts by increasing calcium influx through calcium channels USES: Ethosuximide (Zarontin)is used to treat petit mal seizure Benzodiazepines ACTIONS Is not fully understood, nut it is thought that inhibit neurotransmission by enhancing the effects of GABA in postsynaptic clefts between nerve cells. USES: Clonazepam is used to treat petit mal but tolerance may occur after 6 months so dosage has to be adjusted Clorazepate dipotassium is administered in adjunctive therapy for treating petit mal seizure Diazepam is prescribed to treat acute status epilepticus. It is short acting Drugs used for Pain Management  Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.  The three terms used in relationship to the pain experience are; o Pain perception – also known as nociception – which an individual’s awareness of the feeling or sensation of pain. o Pain threshold – is the point at which an individual first acknowledges or interprets a sensation as being painful. o Pain tolerance – is the individual’s ability to endure pain.  Analgesics o are drugs that relieve pain without producing loss of consciousness or reflex activity. o At present, no completely satisfactory classification of analgesics is available. o Historically they have been categorized based on potency (mild, moderate and strong), origin (opium, semisynthetic, synthetic, coaltar derivative), or additives properties (narcotic and non-narcotic)  o It is divided into:  Opiate Agonists  Opiate partial agonists  Opiate antagonist  Salicylates  Nonsteroidal anti-inflammatory drugs (NSAID) Drug Classification: Opiate Agonists  The term opiate was once used to refer to drugs derived from opium, such as heroin and morphine.  Another outdated term is narcotic. But with the development in recent years of analgesics that are as potent as morphine but do not have its sedative or addictive properties are opiate agonist and opiate partial agonists.  Most of these agents also have the ability to produce physical dependence and are thus considered controlled substances under the Federal Controlled Substances Act of 1970. ACTIONS Group of naturally occurring semisynthetic and synthetic drugs that have the capability to relieve severe pain without loss of consciousness. They act by stimulation of the opiate receptors in the CNS. Subdivided into four group:  Morphine and Morphine Like Derivatives Morphine  Meperidine Like Derivatives Fentanyl  Methadone Like Derivatives Methadone  Other Opiate Agonists Tramadol USES: To relive acute or chronic moderate to severe pain such as that associate d with acute injury, postoperative pain, renal or biliary colic, myocardial infarction or cancer. Tramadol Is a newer synthetic opiate agonist that acts as an analgesic by selectively binding to the u receptors and inhibiting the reuptake of norepinephrine and serotonin. Meperidine Once a commonly prescribed opiod agonist in the management of pain, is less frequently prescribed because of the adverse effects. Use more than 1 to 2 days is not recommended. Long term used can cause renal impairment. Morphine Is effective against acute pain resulting from acute MI, cancer, and dyspnea resulting from pulmonary edema It may be used as preoperative medication It can cause respiratory depression, orthostatic hypotension, miosis, urinary retention, constipation and cough supression An antidote for morphine is opioid antagonist naloxone (Narcan). Special Precautions  With continued, prolonged use opiate agonists may produce tolerance or psychological and physical dependence (addiction).  Addiction may develop after 3 to 6 weeks of continual use. Drug Classification: Opiate Antagonist  Naloxone (Narcan)   Naltrexone Naloxone (Narcan) ACTIONS Naloxone is a so called pure opiate antagonists because it has no effect of its own other than its ability to reverse the CNS depressant effects of opiatesagonists. USES:  Drug of Choice for treatment of respiratory depression when excessive doses of opiate agonist.  Antidote for morphine. Therapeutic Outcome  The primary therapeutic outcome expected from naloxone is reversal of respiratory depression. Drug Classification: Opiate Antagonist  Naloxone (Narcan)  Naltrexone Naltrexone ACTIONS Naltrexone is a pure opiod antagonists that is closely related to naloxone. It differs, however, in that it is active after oral administration and has a considerably longer duration of action. Blocks the effect of opiods by competitive binding at opiod receptors. The mechanism of action of naltrexone in alcoholism is unknown. USES:  Dinish or eliminate opiate seeking behavior by blocking the euphoric reinforcement produced by self-administration of opiates and by preventing the conditioned abstinence syndrome.  Treatment of Alcoholism to support abstinence and reduce relapse rates and alcohol consumption. Therapeutic Outcome  Improved adherence with a substance abuse program because of reduced craving of opiods.  Improved adherence with an alcohol treatment program by diminishing craving for alcohol. Drug Classification: Salicylates  The most common analgesics used for the relief of slight to moderate pain.  There primary pharmacologic effects as analgesic, antipyretic and anti-inflammatory ACTIONS The mechanism of actions are not fully known. Inhibit the formation of prostaglandins that sensitize pain receptors to stimulate causing pain. They inhibit the prostaglandins that produce the signs and symptoms of inflammation. They inhibit the synthesis and release of prostaglandins in the brain that cause the elevation of body temperature. USES:  The combination of pharmacologic effects makes salicylates the drugs of choice for symptomatic relief of discomfort, pain, inflammation or fever associated with bacterial and viral infections, headache, muscle aches and rheumatoid arthritis. Therapeutic Outcomes  The primary therapeutic outcomes expected from salicylates are reduced pain, reduced inflammation, and elimination of fever. Special Precaution  The use of salicylates in children is not recommended because of the associated risk of reye’s syndrome. Drug Classification: Nonsteroidal anti-inflammatory Drugs ACTIONS NSAIDs are also known as aspirin like drugs. They are chemically unrelated to the salicylates but are prostaglandins inhibitors and share many of the same therapeutic actions and adverse effects. Act by blocking cyclooxygenase (COX-1 and COX2). USES: Cyclooxygenase 1 Inhibitors  Diclofenac Rheumatoid and Osteoarthritis, primary dysmenorrhea  Ibuprofen Rheumatoid and Osteoarthritis, primary dysmenorrhea and mild to moderate pain  Ketorolac Injectable analgesic, anti-inflammatory, antipyretic used for acute, short term pain management  Mefenamic Acid Moderate pain or primary dysmenorrhea Cyclooxygenase 2 Inhibitor  Celecoxib Rheumatoid and Osteoarthritis, primary dysmenorrhea, acute pain Therapeutic Outcomes  The primary therapeutic outcomes expected from NSAIDs are reduced pain, reduced inflammation and elimination of fever.