Drugs Acting on CNS and PNS

What is an Action potential?

A sudden change in electrical charge of a nerve cell membrane; the electrical signal by which neurons send information.

What are Afferent neurons?

Neurons or groups of neurons that bring information to the central nervous system; sensory nerves.

What is an Axon?

A long projection from a neuron that carries information from one nerve to another nerve or effector.

What is a Dendrite?

A short projection on a neuron that transmits information.

What is Depolarization?

Opening of sodium channels in a nerve membrane to allow sodium influx, reversing the charge so the membrane is no longer polarized.

What is an Effector cell?

A cell stimulated by a nerve; may be a muscle, a gland, or another nerve cell.

What are Efferent neurons?

Neurons or groups of neurons that carry information from the CNS to an effector; motor neurons are efferent.

What is an Engram?

A short-term memory made up of a reverberating electrical circuit of action potentials.

What is the Forebrain?

Upper level of the brain; consists of two cerebral hemispheres, hypothalamus, thalamus, and limbic system; controls thinking, sensory, and motor coordination.

What are Ganglia?

A group of nerve bodies.

What is the Hindbrain?

The most primitive brain area; includes pons, medulla (vital functions), and cerebellum (motor balance).

What is the Limbic system?

Forebrain area rich in epinephrine, norepinephrine, serotonin; controls emotions.

What is the Midbrain?

Middle brain area; contains many cranial nerves; related to arousal and sleep/wakefulness.

What is a Neurotransmitter?

A chemical produced by a nerve and released when stimulated; reacts with receptor sites to cause a reaction.

What is Repolarization?

Return of the membrane to a resting state with more sodium outside and a negative charge inside.

What is a Schwann cell?

An insulating cell on nerve axons that allows rapid conduction ("leaping") and prevents tiring of the neuron.

What is the Soma?

The cell body of a neuron containing nucleus, cytoplasm, and granules.

What is a Synapse?

The junction between a nerve and an effector, consisting of the presynaptic ending, synaptic cleft, and postsynaptic cell.

What are Benzodiazepines?

Most commonly prescribed anxiolytics. Examples: Alprazolam, Diazepam, Lorazepam, Clonazepam, Midazolam, Chlordiazepoxide, Temazepam, Triazolam, Oxazepam.

What is the mechanism of action of Benzodiazepines?

Increase the effect of GABA, leading to sedative, muscle relaxant, and dependency effects.

What are the indications of Benzodiazepines?

Anxiety disorders, alcohol withdrawal, hyperexcitability, agitation, preoperative anxiety, muscle spasm, epilepsy, tetanus, insomnia.

What are the contraindications of Benzodiazepines?

Allergy, psychosis, acute narrow-angle glaucoma, shock, coma, acute alcohol intoxication, pregnancy.

What are the adverse effects of Benzodiazepines?

Sedation, drowsiness, lethargy, confusion, dry mouth, GI upset, hypotension, arrhythmias, respiratory depression, urinary retention, loss of libido, thrombosis, blood dyscrasias.

What are the nursing considerations for Benzodiazepines?

Assess allergies, liver/kidney function, glaucoma, alcohol intoxication, pregnancy. Prefer oral forms. Give IV only when necessary. Taper gradually. Maintain patient in bed. Modify environment for safety. Void before drug. Give with food if GI upset.

What are the signs of Benzodiazepine toxicity?

Difficulty breathing, confusion, dizziness, blurred vision, weakness, tremors, stupor.

What is the treatment for Benzodiazepine toxicity?

Oxygen therapy, activated charcoal, flumazenil (antidote), hospitalization for monitoring.

What is Buspirone (Buspar)?

Non-benzodiazepine anxiolytic. Causes less sedation, low abuse potential, and no CNS depressant potentiation. Has slow onset, not for panic attacks.

What are Barbiturates?

Examples: Phenobarbital, Secobarbital, Pentobarbital, Amobarbital, Butabarbital. Depress CNS by inhibiting impulse conduction in RAS, depress motor output.

What are the indications of Barbiturates?

Anxiety, insomnia, preoperative sedation, seizures.

What are the contraindications of Barbiturates?

Allergy, addiction to sedatives, porphyria, hepatic/renal impairment, respiratory distress, pregnancy.

What are the adverse effects of Barbiturates?

Drowsiness, lethargy, ataxia, "hangover," paradoxical excitement, GI upset, bradycardia, hypotension, respiratory depression, hallucinations.

What are Tricyclic Antidepressants (TCA)?

Examples: Amitriptyline, Imipramine, Nortriptyline, Doxepin, Clomipramine. Inhibit reuptake of norepinephrine and serotonin → increased stimulation of postsynaptic receptors.

What are the indications of TCAs?

Depression with anxiety/sleep disturbance, enuresis in children >6, OCD (Clomipramine).

What are the contraindications of TCAs?

Allergy, recent MI, concurrent MAOI use, glaucoma, urinary retention, prostate hypertrophy, seizures, hepatic/renal disease, mania.

What are the adverse effects of TCAs?

Sedation, hallucinations, disorientation, anticholinergic effects (dry mouth, constipation), orthostatic hypotension, stroke, alopecia, weight changes.

What are the drug interactions of TCAs?

MAOIs (convulsions, hypertensive crisis, death), cimetidine, fluoxetine.

What are the nursing considerations for TCAs?

Assess for CV risk, taper drug gradually, give major dose at bedtime, expect mood elevation in 2-3 weeks.

What are MAOIs?

Examples: Tranylcypromine (Parnate), Phenelzine (Nardil), Isocarboxazid (Marplan). Inhibit enzyme monoamine oxidase → increase neurotransmitters.

What are the indications of MAOIs?

Depressive disorders not responding to other treatments.

What are the contraindications of MAOIs?

Allergy, pheochromocytoma, hypertension, liver disease, pregnancy.

What are the adverse effects of MAOIs?

Dizziness, nervousness, mania, tremors, insomnia, GI upset, liver toxicity, urinary retention, orthostatic hypotension, hypertensive crisis (with tyramine foods).

What foods interact with MAOIs?

Tyramine-rich foods: aged cheese, wine, sausage, salami, beer, avocado.

What are the drug interactions of MAOIs?

SSRIs (serotonin syndrome), TCAs (hypertensive crisis), sympathomimetics (increased effects).

What are the nursing considerations for MAOIs?

Monitor BP, provide list of food-drug interactions, avoid tyramine foods for 2 weeks post-therapy, monitor liver function.

What are SSRIs?

Examples: Fluoxetine, Sertraline, Paroxetine, Citalopram, Escitalopram. Selectively inhibit serotonin reuptake, increasing serotonin levels.

What are the indications of SSRIs?

Depression, OCD, bulimia, panic disorder, PTSD, social phobias.

What are the contraindications of SSRIs?

Allergy, pregnancy/lactation, renal/hepatic disease, diabetes.

What are the adverse effects of SSRIs?

Headache, dizziness, insomnia, anxiety, GI upset, sexual dysfunction, urinary issues, cough, sweating, rash.

What is Serotonin Syndrome?

Caused by multiple serotonergic drugs. Symptoms: shivering, diarrhea, agitation, tremors, rigidity, high fever, seizures, unconsciousness. Treated by stopping drug, supportive care, cyproheptadine.

What are the nursing considerations for SSRIs?

Monitor suicide risk, administer in morning with food, teach adherence (2-4 weeks for effect), avoid abrupt discontinuation, monitor for serotonin syndrome.

What are Typical Antipsychotics?

Examples: Chlorpromazine, Haloperidol, Fluphenazine, Prochlorperazine. Block dopamine receptors in RAS, reduce positive symptoms of schizophrenia. Cause extrapyramidal symptoms (EPS).

What are the indications of Typical Antipsychotics?

Psychosis, schizophrenia, nausea/vomiting.

What are the contraindications of Typical Antipsychotics?

CNS depression, circulatory collapse, Parkinson's disease, coronary disease, severe hypotension, pregnancy.

What are the adverse effects of Typical Antipsychotics?

EPS, tardive dyskinesia, sedation, orthostatic hypotension, anticholinergic effects, Neuroleptic Malignant Syndrome (NMS), QT prolongation.

What is Neuroleptic Malignant Syndrome (NMS)?

Rare, life-threatening reaction. Symptoms: fever, rigidity, altered mental status, autonomic instability. Treatment: stop drug, supportive care, dantrolene, bromocriptine.

What are the types of Extrapyramidal Symptoms (EPS)?

Acute dystonia, akathisia, parkinsonism, tardive dyskinesia, neuroleptic-induced catatonia.

What are the nursing considerations for Typical Antipsychotics?

Monitor vitals, ECG, CBC, assess EPS, fall precautions, educate on adherence and side effects.

What are Atypical Antipsychotics?

Examples: Risperidone, Olanzapine, Quetiapine, Clozapine, Aripiprazole, Ziprasidone. Block dopamine and serotonin receptors, reduce both positive and negative schizophrenia symptoms.

What are the adverse effects of Atypical Antipsychotics?

Weight gain, metabolic syndrome, sedation, increased prolactin, agranulocytosis (esp. clozapine).

What is Lithium?

A mood stabilizer for bipolar disorder. Alters sodium transport, modulates neurotransmitters (↓ dopamine, ↑ serotonin).

What are the indications of Lithium?

Acute mania, bipolar maintenance, off-label for cluster headaches and depression augmentation.

What are the adverse effects of Lithium?

Nausea, tremors, polyuria, weight gain, hypothyroidism, renal impairment, arrhythmias, lithium toxicity (blurred vision, confusion, seizures, coma).

What are the nursing considerations for Lithium?

Monitor serum levels (0.6-1.2 mEq/L maintenance, >1.5 toxic). Monitor renal, thyroid, electrolytes. Maintain hydration and sodium balance. Avoid NSAIDs, ACE inhibitors, diuretics.

What patient teaching is important for Lithium?

Take with food, do not stop abruptly, report toxicity signs, maintain hydration and diet consistency.

What are CNS Stimulants?

Examples: Methylphenidate (Ritalin). Block dopamine and norepinephrine transporters, ↑ synaptic levels, improve attention and control.

What are the indications of CNS Stimulants?

ADHD, narcolepsy, off-label for depression and fatigue.

What are the contraindications of CNS Stimulants?

Allergy, anxiety, glaucoma, cardiac disease, pregnancy.

What are the adverse effects of CNS Stimulants?

Insomnia, appetite loss, irritability, nausea, ↑ HR/BP, psychosis, growth suppression.

What are the nursing considerations for CNS Stimulants?

Monitor BP, pulse, growth, mood, signs of dependency. Educate: take early in day, avoid caffeine, don't crush ER tablets, drug holidays may help.

What are Hydantoins (anticonvulsants)?

Examples: Phenytoin (Dilantin), Fosphenytoin (Cerebryx), Ethotoin, Mephenytoin. Inhibit sodium influx, stabilize neuronal membranes, reduce repetitive firing, and act as antidysrhythmics.

What are the indications of Hydantoins?

Control of tonic-clonic (grand mal) and partial seizures, status epilepticus (IV), seizure prophylaxis after neurosurgery, antiarrhythmic (off-label).

What are the adverse effects of Hydantoins?

Gingival hyperplasia, drowsiness, ataxia, diplopia, hirsutism, rash, hepatotoxicity, blood dyscrasias, arrhythmias (IV), Stevens-Johnson Syndrome, Purple Glove Syndrome (IV).

What are the nursing considerations for Hydantoins?

Therapeutic serum level 10-20 mcg/mL. Give IV slowly (<50 mcg/min). Monitor CBC, liver, cardiac status. Educate on oral hygiene. Avoid abrupt discontinuation (rebound seizures). Potent enzyme inducer, many drug interactions.

What are Barbiturate anticonvulsants?

Examples: Phenobarbital, Primidone. Increase GABA activity, depress CNS.

What are the indications of Barbiturate anticonvulsants?

Seizure control, status epilepticus, sedation, preoperative anesthesia, insomnia (short-term), anxiety.

What are the adverse effects of Barbiturate anticonvulsants?

Drowsiness, ataxia, cognitive dulling, nausea, dependence, respiratory depression (IV overdose), hepatotoxicity, blood dyscrasias.

What are the nursing considerations for Barbiturate anticonvulsants?

Therapeutic range 15-40 mcg/mL. Monitor respiratory status, liver function, CBC. Avoid alcohol/CNS depressants. High abuse potential.

What are Benzodiazepines as anticonvulsants?

Examples: Diazepam, Lorazepam, Clonazepam, Clorazepate. Increase GABA activity, reduce neuronal excitability.

What are the indications of Benzodiazepines in seizures?

Status epilepticus (IV Diazepam, Lorazepam), absence & myoclonic seizures (Clonazepam), partial seizures.

What are the nursing considerations for Benzodiazepine anticonvulsants?

Short-acting for emergencies (status epilepticus). Risk of dependence, sedation. Monitor respiratory status.

What are Succinimides?

Examples: Ethosuximide (Zarontin), Methsuximide. Inhibit T-type calcium channels, reduce abnormal electrical activity in absence seizures.

What are the indications of Succinimides?

Absence (petit mal) seizures in children/adults.

What are the adverse effects of Succinimides?

GI upset, weight loss, drowsiness, gum swelling, mood changes, Stevens-Johnson Syndrome, blood dyscrasias, lupus-like syndrome, hepatotoxicity.

What are the nursing considerations for Succinimides?

Therapeutic level 40-100 mcg/mL. Monitor CBC, liver/renal function, behavior changes. Educate family to monitor mood.

What are Iminostilbenes?

Examples: Carbamazepine (Tegretol). Block sodium channels, affect GABA and calcium channels.

What are the indications of Iminostilbenes?

Partial and generalized tonic-clonic seizures, trigeminal neuralgia, bipolar disorder (mania), schizoaffective disorder (off-label).

What are the adverse effects of Iminostilbenes?

Drowsiness, blurred vision, rash, photosensitivity, aplastic anemia, agranulocytosis, Stevens-Johnson Syndrome, hyponatremia, hepatotoxicity, suicidal ideation.

What are the nursing considerations for Iminostilbenes?

Therapeutic range 4-12 mcg/mL. Monitor CBC, liver/renal function, electrolytes. Give 1 hr apart from other drugs to avoid interactions. Monitor rash.

What is Valproic Acid?

Examples: Divalproex, Sodium valproate. Increases GABA, modulates sodium and calcium channels, reduces seizures and mood instability.

What are the indications of Valproic Acid?

Seizure disorders (absence, partial, generalized), bipolar disorder, migraine prophylaxis.

What are the adverse effects of Valproic Acid?

Nausea, tremor, weight changes, hair thinning, menstrual irregularities, hepatotoxicity (children), pancreatitis, blood dyscrasias, teratogenicity, suicidal ideation.

What are the nursing considerations for Valproic Acid?

Therapeutic range 50-100 mcg/mL. Monitor liver, CBC, ammonia. Give with food. Avoid abrupt withdrawal. Watch for drug interactions.

What are Anticholinergic drugs for Parkinsonism?

Examples: Benztropine, Biperiden. Block acetylcholine in CNS to restore dopamine-acetylcholine balance.

What are the contraindications of Anticholinergics in Parkinsonism?

Narrow-angle glaucoma, myasthenia gravis.

What are the adverse effects of Anticholinergics in Parkinsonism?

Blurred vision, urinary retention, constipation, dry mouth, confusion, sedation.

What are the nursing considerations for Anticholinergics in Parkinsonism?

Monitor vision, bowel/bladder habits, cognition. Educate on anticholinergic toxicity (blind, dry, red, mad, hot, full).

What are Dopaminergic agents?

Examples: Levodopa/Carbidopa, Amantadine, Pramipexole, Apomorphine, Bromocriptine, Ropinirole, Rotigotine, Rasagiline.

What is the action of Dopaminergic agents?

Increase dopamine levels, stimulate dopamine receptors, inhibit dopamine breakdown.

What are the contraindications of Dopaminergic agents?

Allergy, angle-closure glaucoma, suspicious skin lesions, lactation.

What are the adverse effects of Dopaminergic agents?

Anxiety, nervousness, hypotension, dysphagia, dyskinesia, bizarre breathing, bone marrow depression.