Nervous System: Divisions and Medications

Nervous System Overview

• The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS).
• The CNS includes the brain and spinal cord.
• The PNS includes the somatic and autonomic nervous systems.
• The somatic nervous system is voluntary, controlling muscles with conscious control.
• The autonomic nervous system is involuntary, controlling internal organs.
• The autonomic nervous system is further divided into the sympathetic and parasympathetic nervous systems.
• The sympathetic nervous system controls the "fight or flight" response.
• The parasympathetic nervous system helps the body to rest and relax.

Nervous System Medications

• These medications are used to the treat pain, anxiety, depression, mania, insomnia, convulsions, and schizophrenia.
• These medications are psychotropic and affect both the CNS and PNS.
• The medications work at the synapse, adjusting message transmission between nerves via neurotransmitters.
• Most cross the blood-brain barrier and can have serious side effects.

Autonomic Nervous System Actions

• Cholinergic nerve cells release acetylcholine, relaxing the body.
• Adrenergic nerve cells release epinephrine or norepinephrine, exciting the body.
• The artificial equivalents are used to treat the body if naturally occurring substances aren't enough.

Sympathomimetics

• Mimic the sympathetic nervous system.
• They are used to excite the body and stimulate the "fight or flight" response.
• They restore heart rhythm during cardiac arrest, increase blood pressure during shock, constrict capillaries if bleeding, dilate bronchioles of asthmatics, and dilate pupils for eye procedures.
• Contraindications include hypersensitivity.
• Use with caution in hypertension, myocardial infarction, atrial fibrillation, hypovolemia, in children, and during pregnancy/breastfeeding.
• Examples include Levophed (norepinephrine) and Epinephrine.

Adrenergic Blockers

• They block the action of adrenergics, causing a parasympathetic effect.
• Used to calm the body by slowing heart rate and relaxing vessels.
• To treat cardiac arrhythmias, high blood pressure, migraine headaches, and chest pain.
• Alpha blockers affect vascular smooth muscle and treat hypertension and BPH.
• Beta blockers block epinephrine, slow heart rate and force, and treat hypertension, migraines, and glaucoma.

Parasympathomimetics

• These mimic the parasympathetic system
• Release acetylcholine, which relaxes the fight-flight mechanism.
• They are rarely used due to severe decrease in heart rate and constriction of respiratory passages.
• Examples include nerve gas and pilocarpine (Pilopine), which is used to treat open-angle glaucoma.

Anticholinergics

• Inhibit the parasympathetic nervous system.
• They promote "fight or flight" symptoms, and causes dry secretions.
• They treat asthma, motion sickness, preoperative relaxation, neuromuscular blocking of spasms, and cholinergic crisis
• An example is Atropine (Atropen).

Medications to Control Pain and Fever

• Analgesics reduce pain without eliminating feeling or sensation.
• Choices include salicylates, acetaminophen, nonsteroidal anti-inflammatory drugs, and narcotics.
• Some drugs are also antipyretic (fever-reducing).

Salicylates

• They relieve mild-to-moderate pain and reduce inflammation and fever.
• Aspirin coats platelets making them slippy, causes GI distress, and should not be used in children.
• Methylsalicylate (Bengay) is a topical anti-inflammatory that irritates the skin surface, increasing blood flow and decreasing pain.

Acetaminophen

• It decreases pain and fever, and has no anti-inflammatory effect.
• It is contained in combination cold medications.
• When combined with narcotics, it treats moderate to severe pain, such as oxycodone with acetaminophen (Percocet).

Nonsteroidal Anti-Inflammatory Drugs

• These reduce pain, inflammation, and fever.
• Example: Ibuprofen (Motrin, Advil)
• May be combined with narcotics to relieve moderate to severe pain.
• Oxycodone with ibuprofen (Combunox)

Opioid Analgesics

• Are strong pain killers that suppress the central nervous system
• The active ingredient in most narcotics is opium
• Excess can cause decreased blood pressure, risk of falls or death, and decrease in respirations.
• Examples include morphine, codeine, and fentanyl.
• Addiction potential with long-term use due to euphoria.
• Severe side effects include slowed respirations and decreased blood pressure.

Medications to Treat Anxiety, Insomnia, Sedation, and Seizures

• The limbic system is integral to motions, memory, and level of alertness.
• If the structures in this system are not operating optimally, anxiety, sleeplessness, alertness, and seizures occur.

Anxiolytic Medications

• Reduce the intensity of fears, dangers, and/or tension.
• Calming effect from mild sedation to coma.
• Type of anxiolytic treat anxiety and restlessness through CNS depression.
• Benzodiazepines treat anxiety, seizures, alcohol withdrawal symptoms, and muscle relaxation: Lorazepam (Ativan), Diazepam (Valium), and Alprazolam (Xanax).
• Phenobarbital is a Barbiturate.

Anxiolytics Medications

• Selective serotonin reuptake inhibitors (SSRIs): Celexa (Citalopram), Fluoxetine (Prozac), and Sertraline (Zoloft).
• Serotonin-norepinephrine reuptake inhibitors (SNRIs): Venlafaxine (Effexor XR)
• Tricyclic antidepressants: Amitriptyline (Elavil)
• Tricyclic antidepressants do not work as quickly, but few dependence issues.

Insomnia Medications

• The medications induce sleep by depressing CNS with Barbiturates and with Non-narcotic benzodiazepine hypnotics.
• Non-narcotic benzodiazepine hypnotics: Zolpidem (Ambien) and Eszopicolone (Lunesta)
• There are few side effects and a possible addiction risk if it does affect the entire CNS.

Barbiturates and Antiseizure Medications

• Hydantoins such as phenytoin (Dilantin) delay sodium from crossing neural membranes, calming cells.
• It is drug of choice for tonic-clonic (grand mal) and partial seizures
• Barbiturates such as phenobarbital (Luminal) are used for tonic-clonic and febrile seizures
• Succinimides such as ethosuximide (Zarontin) delay calcium moving over neurons to relax nerve cells.
• It is drug of choice for absence (petit mal) seizures

Anti-Seizure Cont..

• Gamma-aminobutyric acid (GABA) is a naturally occurring neurotransmitter inhibitor.
• Increased presence decreases seizure activity with Vigabatrin (Sabril)
• Benzodiazepines such as diazepam (Valium) intensify effect of GABA transmitters in brain.
• Other medications: Lamictal (lamotrigine), Gabitril (tiagabine), Topamax (topiramate), and Tegretol (carbamazepine).
• Seizure reducing medication manage alcohol withdrawal symptoms by reducing anxiety.

Behavioral, Emotional, and Mood Disorder Medications

• Behavioral and emotional disorders is a broad term used to include a wide variety of mental health diagnoses, and make have difficulty initiating and maintaining relationships.
• Mood Disorders are Characterized by elevation or depression on one’s mood.

Central Nervous System Stimulants

• Used to treat ADD, ADHD, obesity, and sleep disorders
• They treat ADD and ADHD with Amphetamine dextroamphetamine (Adderall), pemoline (Cylert), and methylphenidate (Ritalin).
• Obesity is treated with Amphetamines such as phentermine (Zantryl) to increase metabolism.
• Narcolepsy is treated with Modafinil (Provigil) or armodafinil (Nuvigil) to stay awake and alert.

Antidepressants

• When neurotransmitters are depleted, patient does not think clearly, and mood is depressed.
• Antidepressants preserve neurotransmitters at the synapse.
• Four categories: Monoamine oxidase inhibitors (MAOIs), Tricyclic antidepressants (TCAs), Selective serotonin reuptake inhibitors (SSRIs), and Serotonin-norepinephrine reuptake inhibitors (SNRIs).

Monoamine Oxidase Inhibitors

• Inhibit enzyme that stops action of neurotransmitters.
• Example: Selegiline (Eldepryl).
• Requires dietary exclusion foods containing tyramine ex, avocados, bananas, beer, bologna, chocolate and aged dairy products
• Rarely prescribed today.

Tricyclic Antidepressants

• Have Three-ring chemical structure that keeps norepinephrine and serotonin at nerve terminals.
• Drug of choice if patient has insomnia due to sedative side.
• The side effect of Elavil (amitriptyline) often has many side effects.
• This Drug of choice for severe depression and inpatient treatment.

Selective Serotonin Reuptake Inhibitors (SSRIs)

• Prevent serotonin from being used up at the synapse.
• This effects in Few side, making it usually the first choice.
• Examples; Celexa (citalopram), Prozac (fluoxetine), Paxil (paroxetine), and Zoloft (sertraline).

Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)

• Block reuptake of serotonin and norepinephrine
• An Increase in these levels elevates mood.
• Examples are Venlafaxine (Effexor XR), Desvenlafaxine (Pritiz), and Duloxetine (Cymbalta).

Mood Stabilizers

• Stabilize extreme mood shifts seen in with bipolar disorder and schizophrenia.
• Most common: Lithium (has normothermia lithium Level).
• Its range has a Small therapeutic parameter.
• Lithium is a salt, so patient should avoid table salt and Regular blood tests due Lithium toxicity.
• Other drugs are lamotrigine (Lamictal) and valproic acid (Depakene, Depakote)

Antipsychotic Medications

• Thorazine (chlorpromazine), Clopine (clozapine), Mellaril (thioridazine) treat treat abnormal actions and behaviors or psychoses such as talking and interacting with situation only they can see and hear.
• It's use for other conditions include nausea, vomiting, dementia, agitation, and related spasms.
• You must always know why a patient is on this drug.

Dementia

• Progressive irreversible decline in mental.
• Alzheimer’s disease is it's most common underlying cause
• The Goal of therapy is to prevent or slow down further deterioration without cure.
• Aricept (donepezil HCL), which, cholinesterase inhibitor showing promise in slowing down progression.

Parkinson’s Disease

• Is a Degenerative disorder of CNS, causing Shuffle of walk and potentially, falls
• It can cause Neurons that produce dopamine die; which caused the muscle movements become disorganized
• A Lack of dopamine and increase in acetylcholine result sin tremors, slow movement, rigid muscles, balance problems must be addressed
• Antiparkinsonian drugs focus on keeping dopamine and acetylcholine at the nerve synapse

Parkinson’s Disease Treatments

• The Antiparkinsonian drugs are Dopaminergic (replace or increase dopamine), and Cholinergic agents (inhibit action of acetylcholine).
• Dopaminergic medication can be comprised of Eldepryl (selegiline), Parlodel (bromocriptine), Requip (ropinirole), Sinemet (carbidopa/levodopa).
• Cholinergic agents such as Biperiden (Akineton).
• Patients need combination drugs to achieve sufficient dopamine levels and to have a drug holiday.

Local Anesthesia

• Creates a lack of feeling without a loss of consciousness.
• Creams: EMLA (lidocaine/prilocaine).
• Aerosol spray: Exactacain (Benzocaine/butamben/tetracaine).
• Otic medication: American otic (benzocaine).
• Injectable solution examples: Xylocaine (lidocaine).
• Local Anesthesia, as Classified as amides and esters, have Amides that last longer,with rare adverse effects and allergies ,however, Esters have potential severe allergic reactions and thus are limited to topical preparations

General Anesthesia

• Creates loss of both feeling and consciousness.
• It starts with IV infusion of Midazolam (Versed), propofol (Diprivan), or ketamine (Ketalar) used initially for longer procedures followed by Inhalation therapy.
• Inhaled gas examples: Desflurane (Suprane), isoflurane (Forane), sevoflurane (Ultane).
• These are Volatile and can depress respiratory and cardiovascular function.
• Use of IV medications allows lower doses of inhalation therapy, thus reduced risk of severe side effects with inhalation therapy.

Alcohol Uses and Affects

• Alcohol is a CNS depressant, and is rarely prescribed.
• It Interacts with confusion, peripheral vasodilation, increased heart rate, electrolyte imbalances, decreased motor coordination, unsteady gait, slurred speech
• Prolonged use can permanently damage CNS and liver.
• Early signs and symptoms of chronic alcoholism is; Irritability, tremors, GI disorders, frequent falls, blackouts, confusion, neural and muscle weakness, and conjunctivitis.
• Treatments: Disulfiram (Antabuse), behavior modification, vitamin B injections, and dietary changes.