Pharmacology exam 2 - Good luck gang

CNS Depressants – Benzodiazepines

  • Boost GABA (a brain chemical that calms things down) to stop overactivity in brain cells.

  • Controlled substance (Schedule IV); can cause physical dependence, tolerance (needing more for the same effect), and withdrawal symptoms; not safe for pregnancy (category D/X).

  • Serious warning: mixing with other calming drugs (like pain medications or alcohol) can dangerously slow breathing, even causing death.

  • How they work: They attach to ext{GABA}_A receptors, letting more 'calming' particles (Cl⁻ ions) into brain cells, which makes the cells less excitable.

  • Uses:

    • Quick relief for acute anxiety, short-term sleep problems (insomnia), severe seizures or continuous seizures (status epilepticus), skeletal muscle relaxation, alcohol withdrawal, light sedation for medical procedures, and for children with sleepwalking or night terrors.

  • Don't use if:

    • Allergic, have a type of eye problem called narrow-angle glaucoma (can increase eye pressure), are pregnant, or have severe breathing problems.

  • Side effects:

    • Brain/Nervous System: headache, feeling dizzy, sleepy, sluggish, fuzzy thinking, 'hang-over' feeling, and sometimes increased restlessness/agitation when stopped too quickly.

    • Other: clumsiness (ataxia), unexpected agitation (in children or older adults), higher risk of falls (especially for older adults).

  • Overdose: causes extreme sleepiness, confusion, slow reflexes, coma, wide pupils, and shallow breathing. The antidote is Flumazenil, given by IV.

Duration Groups & Key Drugs

  • Long-acting: Last a long time. Examples: Diazepam, Clonazepam, Chlordiazepoxide.

  • Intermediate: Last a moderate amount of time. Examples: Alprazolam, Lorazepam, Temazepam.

  • Short: Last a short time. Examples: Midazolam, Triazolam.

Individual Prototypes

  • Diazepam: Can be given by mouth (PO), IV, or rectally (PR). Typical dose 2{-}10 ext{ mg} three times a day (TID). Works fastest in 1{-}2 hours, lasts 12{-}24 hours.

  • Alprazolam: Given by mouth (PO). Typical dose 0.25{-}0.5 ext{ mg} three times a day (TID). Starts working in 30{-}60 minutes, lasts about 6 hours.

Non-benzodiazepine Hypnotics ("Z-drugs")

  • Work on GABA receptors (like benzodiazepines but with a different structure) to help you fall asleep and stay asleep. They are controlled substances (Schedule IV).

  • Key Drugs & Points:

    • Eszopiclone: Take 1{-}3 ext{ mg} at bedtime (HS) for about 8 hours of sleep; can cause a metallic taste; it's the first agent approved for long-term use.

    • Zolpidem: Take 5/10 ext{ mg} at bedtime (HS); lasts 6{-}8 hours; can cause sleepwalking; less likely to cause daytime sleepiness.

    • Zaleplon: Stays in the body for a very short time (very short half-life), so it only helps you fall asleep, not necessarily stay asleep.

    • Ramelteon: Acts like melatonin, a natural hormone, to help you fall asleep.

    • Suvorexant: Blocks a brain chemical called orexin to help you stay asleep; lasts longer in the body.

Skeletal Muscle Relaxants

  • Most work by calming signals in the brain and spinal cord to relax muscles ('centrally acting'); Dantrolene is an exception, working directly on the muscle itself ('peripheral').

  • Uses: Acute muscle spasms (like low back pain, fibromyalgia), muscle stiffness and tightness (spasticity) from conditions like multiple sclerosis (MS) or spinal cord injury (SCI), and as a helper during physical therapy.

  • Common Medications:

    • Baclofen: Works on ext{GABA}_B receptors in the spinal cord; comes in pill form or as a pump (PO/IT); start with a low dose and increase slowly; side effects include drowsiness, weakness, low blood pressure, increased urination, and high blood sugar.

    • Cyclobenzaprine: Acts in the brainstem; has side effects similar to anticholinergic drugs (e.g., dry mouth, blurred vision); avoid using for more than 2{-}3 weeks.

    • Tizanidine (affects alpha-2 receptors); Methocarbamol; Carisoprodol (can be abused); Metaxalone; Chlorzoxazone.

  • Important Nursing Points: Take precautions to prevent falls, do not drive, avoid alcohol, don't stop suddenly (taper off), and monitor vital signs (blood pressure, heart rate).

Anti-Parkinson Drugs

  • Parkinson's Disease (PD) happens when there's not enough dopamine (a brain chemical important for movement) and relatively too much acetylcholine (another brain chemical).

  • Symptoms are easily remembered by the mnemonic TRAP:

    • Tremor (shaking)

    • Rigidity (stiffness)

    • Akinesia (slowness of movement, also called bradykinesia)

    • Postural instability (problems with balance).

  • Treatment aim is to increase dopamine in the brain or mimic its effects. These drugs often become less effective after about 2 years.

Classes & Examples

  1. Dopamine Replacement: Levodopa + Carbidopa (Sinemet) – Levodopa turns into dopamine in the brain; Carbidopa helps more Levodopa reach the brain by blocking its breakdown elsewhere in the body. It takes 2{-}3 weeks to start working. Avoid Vitamin B6 supplements, high-protein meals, and certain antidepressants (non-selective MAOIs) as they can interfere.

  2. Dopamine Modulator: Amantadine – Increases the release of dopamine and slows its reabsorption in the brain.

  3. ext{MAO-B} Inhibitors: Selegiline, Rasagiline – They stop dopamine from breaking down in the brain, which means fewer diet restrictions related to tyramine (a substance found in some foods that can cause dangerous blood pressure spikes with older MAOIs).

  4. ext{COMT} Inhibitors: Tolcapone/Entacapone – These drugs block the enzyme COMT, which breaks down dopamine, increasing its availability in both the body and brain.

  5. Anticholinergics: Benztropine – Reduces tremor and stiffness. Side effects include dry mouth, feeling hot, difficulty urinating, and increased body temperature.

Anti-Epileptic Drugs (AEDs)

  • Goal: To stabilize brain cells, making them less likely to trigger a seizure and stopping seizures from spreading, while maintaining a good quality of life.

  • How they work: They can block sodium ( ext{Na}^+) or calcium ( ext{Ca}^{2+}) channels, boost calming brain chemicals (like GABA), or block stimulating ones (like glutamate).

  • Treatment is personalized for each patient; blood levels may be monitored (for some drugs); don't stop suddenly (taper off); serious warning: can increase thoughts of suicide (black-box warning).

Traditional AEDs & Key Issues

  • Phenytoin: Target blood level is 10{-}20 ext{ µg/mL} for effectiveness; blocks sodium channels. Side effects: gum overgrowth (gingival hyperplasia), severe skin rash (Stevens-Johnson Syndrome - SJS), 'Purple Glove' syndrome (skin discoloration/swelling if IV leaks), and bone weakening (osteopenia). When given by IV, it must be administered slowly (no faster than 50 ext{ mg/min}) and only with normal saline.

  • Phenobarbital: Boosts GABA; speeds up the breakdown of other drugs (enzyme inducer); causes drowsiness; can cause SJS; stays in the body for a long time (half-life of about 80 hours).

  • Carbamazepine: Can increase its own breakdown over time (auto-induction), meaning the body gets rid of it faster; avoid grapefruit juice; rare but serious side effect: aplastic anemia (a condition where the bone marrow doesn't produce enough new blood cells).

  • Valproic acid: Increases GABA and blocks sodium channels; can cause liver damage (hepatotoxicity), pancreas inflammation (pancreatitis), weight gain, and birth defects (teratogenic, not safe in pregnancy).

Newer AEDs (high-yield names)

  • Lamotrigine (risk of severe skin rash like SJS), Levetiracetam (can cause mood/behavior changes), Topiramate (risk of kidney stones, increased eye pressure/glaucoma), Gabapentin/Pregabalin (often used for nerve pain, also for seizures), Zonisamide (avoid if sulfa allergy), Lacosamide, Oxcarbazepine.

Status Epilepticus

  • Definition: A seizure lasting 5 minutes or longer, or multiple seizures without full recovery in between; it's a medical emergency.

  • First-line treatment: IV Lorazepam (0.1 ext{ mg/kg}); Diazepam or Midazolam can also be used, followed by a larger dose of another AED to prevent further seizures.

CNS Stimulants

  • These drugs stimulate the central nervous system (CNS) by increasing the release or blocking the reabsorption of brain chemicals like dopamine and norepinephrine, which boost alertness and energy.

  • Uses: Attention-Deficit/Hyperactivity Disorder (ADHD), narcolepsy (a sleep disorder), obesity (as appetite suppressants, called anorexiants), and migraines (specifically triptans).

  • High potential for abuse (controlled substance, Schedule II); start with a low dose and slowly increase; sometimes 'drug holidays' (short breaks from the medication) are recommended.

ADHD/Narcolepsy Agents

  • Examples: Amphetamine salts (Adderall), Dextroamphetamine, Lisdexamfetamine, Methamphetamine, Methylphenidate (Ritalin), and Modafinil (Provigil, which is not an amphetamine).

  • Don't use if:

    • Severe heart disease, glaucoma, severe anxiety, have used MAO inhibitor antidepressants in the last 14 days, or are pregnant.

  • Side effects: High blood pressure, fast heart rate, trouble sleeping (insomnia), loss of appetite/weight loss, and in rare cases, psychosis.

  • Important Nursing Points: Check baseline heart tracing (ECG) and blood pressure, monitor weight; give the first dose in the morning, and the last dose at least 6 hours before bedtime; for children, give after breakfast; monitor their growth.

Anorexiants (Appetite Suppressants)

  • Examples: Benzphetamine, Methamphetamine; Orlistat (works by blocking fat absorption, not a stimulant).

  • Don't use if:

    • Heart disease, high blood pressure, overactive thyroid (hyperthyroidism), or on MAO inhibitors.

Antimigraine – Triptans (used for migraine attacks)

  • Sumatriptan is the main example; others include Rizatriptan, Zolmitriptan, etc.

  • Abortive: Used to stop a migraine once it starts by causing blood vessels in the brain to narrow (cranial vasoconstriction).

  • Don't use if:

    • Coronary artery disease (CAD), peripheral artery disease (PAD), uncontrolled high blood pressure, history of stroke or a specific type of migraine (hemiplegic migraine), severe liver or kidney problems, or during pregnancy (Category C).

  • Side effects: Chest tightness, high blood pressure, tingling or numbness (paresthesias), pain at the injection site, and flushing (redness).

  • Dosing: Can be repeated after 2 hours if needed (prn); maximum 200 ext{ mg} in 24 hours.

Psychotherapeutics

Antidepressants

  • Take 2{-}4 weeks to start working; serious warning: can increase thoughts of suicide (black-box warning), especially in those under 24 years old.

  • Classes & Key Points:

    • TCAs (Tricyclic Antidepressants): Examples include Amitriptyline, Imipramine. They block the reabsorption of serotonin and norepinephrine (brain chemicals) and have anticholinergic side effects (e.g., dry mouth, blurred vision). They are dangerous in overdose due to heart rhythm problems.

    • SSRIs (Selective Serotonin Reuptake Inhibitors): Examples include Fluoxetine, Sertraline, Paroxetine, Citalopram, Escitalopram. Often first-choice; side effects: stomach upset, insomnia, sexual problems, weight gain, serotonin syndrome (a serious drug reaction resulting from too much serotonin), and withdrawal symptoms if stopped suddenly (FINISH mnemonic).

    • SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors): Examples include Venlafaxine, Duloxetine. Similar to SSRIs, but can also cause high blood pressure.

    • MAOIs (Monoamine Oxidase Inhibitors): Examples include Phenelzine, Isocarboxazid, Tranylcypromine, Selegiline patch. They require a special diet (tyramine-restricted) to avoid dangerously high blood pressure (hypertensive crisis). They interact with many drugs (e.g., meperidine, decongestants).

    • Atypical Antidepressants: Bupropion (blocks the reabsorption of norepinephrine NE and dopamine DA) – Less likely to cause sexual side effects; avoid if you have a seizure disorder.

  • St. John’s Wort: An herbal supplement with effects similar to SSRIs; increases the risk of serotonin syndrome.

Mood Stabiliser – Lithium

  • Used to manage episodes of elevated mood (mania/hypomania) in bipolar disorder, helping to prevent future mood swings.

  • Therapeutic range (the blood level needed for effectiveness) is 0.5{-}1.2 ext{ mEq/L} (levels above 2 ext{ mEq/L} are toxic).

  • Side effects: Tremors, increased urination/thirst (polyuria), low thyroid function (hypothyroid), stomach upset (GI issues), and irregular heart rhythms (dysrhythmia).

  • Drug/Sodium/Fluid Balance is Critical: Maintaining proper balance of other medications, sodium (salt), and fluids is crucial. Avoid certain diuretics (thiazides), blood pressure medications (ACE inhibitors), and common pain relievers (NSAIDs), as they can increase lithium levels and lead to toxicity.

  • Monitoring: Monitor blood levels 2{-}3 times a week initially, then every 3 months. Blood samples should be taken about 12 hours after the last dose (called a trough level, generally the lowest concentration of the drug in the blood).

Antipsychotics

  • Typical Antipsychotics (e.g., Haloperidol): Primarily block dopamine ( ext{D}_2) receptors; used for psychosis and Tourette's syndrome. Side effects: movement problems (Extrapyramidal Symptoms - EPS), involuntary repetitive movements (tardive dyskinesia), a rare life-threatening reaction (Neuroleptic Malignant Syndrome - NMS), and a specific heart rhythm abnormality (QT prolongation). Long-acting injectable forms (IM depot) are available for patients who have trouble taking daily pills.

  • Atypical Antipsychotics (e.g., Risperidone, Quetiapine, Aripiprazole): Block both dopamine ( ext{D}_2) and serotonin ( ext{5-HT}) receptors; generally cause fewer movement problems than typical antipsychotics, but can lead to metabolic syndrome (a group of conditions including weight gain, high blood sugar, and high cholesterol).

  • Don't use in patients with dementia-related psychosis, as it increases the risk of death.

Autonomic Drugs

Adrenergic Agonists (Catecholamines)

  • These drugs mimic or enhance the effects of adrenaline and noradrenaline, activating receptors in the body that control 'fight or flight' functions.

  • Receptor Map:

    • Alpha-1 ($\alpha _1$) receptors: Cause blood vessels to narrow (vasoconstriction), increasing blood pressure.

    • Alpha-2 ($\alpha _2$) receptors: Calm the central nervous system.

    • Beta-1 ($\beta _1$) receptors: Mainly affect the heart (increase heart rate and pumping strength/contractility) and kidneys (release renin for blood pressure regulation).

    • Beta-2 ($\beta _2$) receptors: Relax airways in the lungs (bronchodilation) and widen blood vessels (vasodilation).

    • Dopamine (DA) receptors: Affect blood flow, especially to the kidneys and gut.

  • Norepinephrine: Primarily affects alpha-1 more than beta-1 receptors; used to treat very low blood pressure and shock (given by IV into a large central vein). Monitor for leakage out of the vein (extravasation) as it can damage tissue; an antidote called phentolamine can be injected into the affected area.

  • Epinephrine: Affects all alpha and beta receptors; used for cardiac arrest (ACLS protocol, 1 ext{ mg} IV every 3{-}5 minutes of 1:10,000 concentration) and severe allergic reactions (anaphylaxis, 0.3 ext{ mg} intramuscularly - IM - of 1:1,000 concentration).

  • Dopamine: Effects depend on the dose (low doses primarily affect dopamine receptors; moderate doses affect beta-1; high doses affect alpha-1).

  • Dobutamine: Mainly affects beta-1 receptors to increase the heart's pumping strength (inotrope); used for heart failure and after heart surgery.

  • Phenylephrine: Primarily alpha-1 effects – raises blood pressure (vasopressor), relieves nasal congestion, and dilates pupils (mydriasis).

  • Midodrine: An oral alpha-1 agonist used for low blood pressure when standing up (orthostatic hypotension); the last dose should be taken at least 4 hours before bedtime to prevent high blood pressure while lying down (supine hypertension).

  • Fenoldopam: A dopamine-1 receptor activator that dilates blood vessels for very high blood pressure emergencies (hypertensive emergencies); also protects the kidneys (renal protective).

  • Mirabegron: A beta-3 agonist used for overactive bladder.

  • Important Nursing Points: Often used in the Intensive Care Unit (ICU); adjust dose slowly (titrate); may require an arterial line to monitor blood pressure closely; monitor mean arterial pressure (MAP) and urine output (aim for more than 30 ext{ mL per hour}); watch closely for extravasation (leakage from vein) as it can cause serious tissue damage (black-box warning for tissue necrosis).

Adrenergic Blockers – Alpha-1 ($\alpha _1$) Antagonists

  • How they work: They block alpha-1 receptors, causing blood vessels to widen (vasodilation), which lowers blood pressure and relaxes the bladder neck and prostate.

  • Uses: High blood pressure (HTN), Raynaud's phenomenon (a condition affecting blood flow to fingers/toes), enlarged prostate (Benign Prostatic Hyperplasia - BPH), a rare tumor called pheochromocytoma, and to treat tissue damage from catecholamine extravasation (leakage of adrenergic drugs from a vein).

  • Medications:

    • Tamsulosin (Flomax): Used mainly for enlarged prostate (BPH) and to help pass kidney stones; avoid using with erectile dysfunction drugs.

    • Terazosin, Doxazosin: Can cause a sudden drop in blood pressure and fainting with the first dose ('first-dose syncope') due to severe hypotension.

    • Alfuzosin: Used for enlarged prostate (BPH).

    • Phentolamine: Injected under the skin (SC infiltration) for catecholamine extravasation; also used to diagnose and treat pheochromocytoma.

  • Side effects: Dizziness, headache, low blood pressure upon standing (orthostatic hypotension), stuffy nose (nasal congestion), and a reflex increase in heart rate (reflex tachycardia).

Cholinergic Drugs (Parasympathomimetics)

  • These drugs mimic or enhance the action of acetylcholine, a neurotransmitter that controls 'rest and digest' functions in the body.

  • Directly acting (directly activate acetylcholine receptors):

    • Bethanechol: Helps with urinary retention (difficulty emptying bladder).

    • Pilocarpine/Carbachol: Used for glaucoma (to lower eye pressure).

    • Succinylcholine: A muscle paralytic (neuromuscular blocker) used in surgery to relax muscles.

  • Indirectly acting (Acetylcholinesterase inhibitors - they stop the breakdown of acetylcholine, increasing its levels):

    • Donepezil, Rivastigmine: Used for Alzheimer’s disease to improve cognitive function.

    • Pyridostigmine: Used for Myasthenia Gravis (a muscle weakness disorder), to reverse muscle paralysis after surgery, and for exposure to nerve agents (organophosphates).

    • Edrophonium: Used to diagnose Myasthenia Gravis (Edrophonium test).

  • Too much stimulation can lead to a 'cholinergic crisis,' causing symptoms like excessive Salivation, Lacrimation (watery eyes), Urination, Diarrhea, GI Cramps, Emesis (vomiting), and Miosis (constricted pupils). The antidotes are Atropine and Pralidoxime.

  • Important Nursing Points: Don't use if there's a blockage in the stomach/gut or urinary tract, or if the patient has asthma/COPD, or a slow heart rate (bradycardia). Give Bethanechol on an empty stomach. Monitor blood pressure and heart rate; also check blood counts (CBC) for Donepezil due to a risk of stomach bleeding.

Anticholinergic Drugs

  • These drugs block muscarinic receptors (a type of acetylcholine receptor), leading to effects similar to stimulating the 'fight or flight' (sympathetic) nervous system.

  • Atropine is the main example: Used for a slow heart rate with symptoms (symptomatic bradycardia), to reduce saliva/mucus before surgery, and as an antidote for nerve agent (organophosphate) poisoning.

  • Other Medications & Uses:

    • Scopolamine: For motion sickness (often as a transdermal patch).

    • Benztropine: Used for Parkinson's disease and to treat movement side effects (EPS) from antipsychotic drugs.

    • Dicyclomine: For intestinal spasms in Irritable Bowel Syndrome (IBS).

    • Oxybutynin/Tolterodine: Used for overactive bladder (specifically targeting M3 receptors).

    • Ipratropium: Inhaled for bronchodilation (widening of airways) in COPD/asthma.

  • Don't use if:

    • Angle-closure glaucoma, Myasthenia Gravis, blockage in the stomach/gut, or severe ulcerative colitis.

  • Anticholinergic Toxicity: Too much anticholinergic drug can cause a dangerous 'anticholinergic toxidrome,' creating symptoms often described by the rhyme: “hot as a hare” (fever), “dry as a bone” (dry mouth, no sweating), “blind as a bat” (blurred vision, wide pupils), “red as a beet” (flushed skin), “mad as a hatter” (confusion/delirium) – along with fast or irregular heart rhythms (tachy-dysrhythmias). Management is supportive care; an antidote called Physostigmine may be given.

  • Important Nursing & Education Points: Encourage fluids and fiber (to prevent constipation), good oral hygiene (for dry mouth), wear sunglasses (due to light sensitivity/photophobia), avoid overheating (as sweating is reduced), and watch for fall risk in older adults (due to confusion or delirium).

General Nursing Process Across CNS/ANS Drugs

  • Assessment: Check vital signs (e.g., blood pressure, heart rate), neurological status, mental health, sleep patterns, substance use history, obtain lab results (e.g., complete blood count - CBC, liver function tests - LFT, renal function tests - RFT), identify contraindications (reasons not to use the drug), check for pregnancy, and obtain a baseline heart tracing (ECG).

  • Diagnosis/Goals: Focus on patient safety (preventing falls, managing blood pressure), controlling symptoms (e.g., reducing anxiety, improving sleep, being seizure-free, pain-free movement), ensuring medication adherence, and addressing any knowledge deficits about the medication.

  • Implementation: Start with a low dose and slowly increase (start low–go slow); administer at optimal times (e.g., stimulants in the morning, hypnotics at bedtime); monitor therapeutic blood levels for certain drugs (e.g., phenytoin, lithium); and discontinue medications by gradually reducing the dose (taper discontinuations) rather than stopping abruptly.

  • Evaluation: Assess if symptoms are relieved, if severe side effects are absent, if lab parameters are stable, if the patient understands their medication plan, and if they can maintain their daily activities (ADLs).