Essential Medications: Clinical Pharmacology & Patient Care

Pharmacology Fundamentals

Pharmacokinetics: What the Body Does to the Drug

Phases:

1. Absorption – How a drug enters the bloodstream

2. Distribution – How a drug travels through the body

3. Metabolism – How a drug is broken down (mainly in the liver)

4. Excretion – How a drug leaves the body (mainly through the kidneys)

🧠 Memory Trick: ADME — Absorb, Deliver, Metabolize, Exit

Pharmacodynamics: What the Drug Does to the Body

• Describes how a drug works at the target site

• Involves receptor binding, enzyme interactions, and therapeutic vs. side effects

Examples:

• Beta blockers bind to beta receptors → slow heart rate

• Insulin binds to insulin receptors → lowers blood sugar

Drug Release Types: ER, IR, SR, XL, CR

⚠️ ER drugs can cause overdose if crushed!

Medication Reconciliation (Med Rec)

• Definition: Process of comparing a patient’s current medications with new orders

• Purpose: Avoid medication errors (omissions, duplications, interactions)

• When It's Done:

  • On admission

  • At transfer

  • On discharge

🔎 Why it matters: Ensures safe, continuous care across settings.

Medication Administration: The 6 Rights

Always follow the 6 Rights of Medication Administration:

1. ✅ Right patient

2. ✅ Right medication

3. ✅ Right dose

4. ✅ Right time

5. ✅ Right route

6. ✅ Right documentation

Extra Tips:

• Always verify IV compatibility

• Do not mix medications in enteral feeding tubes without checking

• Always use aseptic technique with injections

• Check expiration dates and allergies

1. Levothyroxine

• Class: Thyroid hormone (T4) replacement

• MOA: Synthetic form of thyroxine (T4); increases metabolic rate by replacing deficient thyroid hormone

• Therapeutic Uses: Hypothyroidism (primary treatment)

• Side Effects: Hyperthyroidism symptoms if overcorrected: anxiety, tachycardia, weight loss, heat intolerance

• Patient Education:

  • Take on an empty stomach in the morning (30–60 min before food)

  • Do not take with calcium, iron, or antacids — separate by 4 hours

  • Lifelong therapy — do not stop abruptly

  • Monitor TSH regularly

2. Lorazepam (Ativan)

• Class: Benzodiazepine, sedative-hypnotic, anxiolytic

• MOA: GABA receptor agonist — enhances GABA's inhibitory effect on the CNS

• Therapeutic Uses: Anxiety, insomnia, seizures, alcohol withdrawal, pre-op sedation

• Side Effects:

  • Drowsiness, lightheadedness, amnesia

  • Respiratory depression

  • Paradoxical reactions (especially in elderly)

  • Risk of abuse and dependence (BBW)

• Patient Education:

  • Do not combine with alcohol or other CNS depressants

  • Take exactly as prescribed — do not stop suddenly

3. Fluoxetine (Prozac)

• Class: SSRI (Selective Serotonin Reuptake Inhibitor)

• MOA: Inhibits reuptake of serotonin in the brain — increases serotonin availability

• Therapeutic Uses: Depression, anxiety, OCD, PTSD, PMDD

• Side Effects:

  • Insomnia, agitation, sexual dysfunction, weight changes

  • GI upset, headache

  • Serotonin Syndrome (rare but serious): fever, agitation, tremors

  • Suicidal thoughts (especially in youth) — BBW

• Patient Education:

  • Takes a few weeks to work

  • Do not stop suddenly — withdrawal can cause dizziness, brain zaps

  • Report signs of serotonin syndrome

4. Opioids (General)

• Class: Narcotic analgesics

• MOA: Bind to opioid receptors (mu, kappa) in CNS — block pain signals

• Therapeutic Uses: Moderate to severe pain, post-op, cancer, trauma

• Side Effects:

  • Respiratory depression (major risk)

  • Constipation, nausea, sedation, euphoria

  • Dependence, tolerance, misuse (BBW)

• Patient Education:

  • Increase fiber to prevent constipation

  • Avoid alcohol

5. NSAIDs (e.g., Ibuprofen, Naproxen)

• Class: Nonsteroidal Anti-Inflammatory Drugs

• MOA: Inhibit COX-1 and COX-2 enzymes → reduce prostaglandin synthesis → decrease inflammation, pain, fever

• Therapeutic Uses: Pain, inflammation, fever, arthritis, dysmenorrhea

• Side Effects:

  • GI upset, ulcers, bleeding (especially with long-term use)

  • Kidney injury

  • Increased cardiovascular risk (MI, stroke)

• Patient Education:

  • Take with food to reduce stomach upset

  • Avoid alcohol and other NSAIDs

  • Monitor for black stools (GI bleeding) or decreased urine output

  • Do not mix with ACE inhibitors or diuretics (increases kidney risk)

6. Gentamicin

• Class: Aminoglycoside antibiotic

• MOA: Inhibits bacterial protein synthesis (30S ribosomal subunit) → bactericidal

• Therapeutic Uses: Serious gram-negative infections, sepsis, UTIs, respiratory infections

• Side Effects:

  • Nephrotoxicity (kidney damage)

  • Ototoxicity (hearing loss, tinnitus, vertigo)

  • Neurotoxicity

• Patient Education:

  • Monitor kidney function (BUN/Creatinine) and hearing

  • Report ringing in ears (tinnitus)

7. IV Fluids: Hypotonic vs. Hypertonic vs. Isotonic

*D5W is isotonic in the bag, but becomes hypotonic once dextrose is metabolized in the body.

• Patient Education:

  • Monitor for signs of fluid overload (edema, shortness of breath)

  • Watch electrolytes closely

  • Follow provider instructions for fluid type carefully

8. Atorvastatin (Lipitor)

• Class: HMG-CoA reductase inhibitor (statin)

• MOA: Inhibits cholesterol synthesis in liver → increases LDL receptor uptake → decreases LDL

• Therapeutic Uses: High cholesterol, prevention of cardiovascular events (stroke, MI)

• Side Effects:

  • Muscle pain (myopathy, rare rhabdomyolysis)

  • GI upset

  • Liver enzyme elevation

• Patient Education:

  • Take in the evening (when the liver makes most cholesterol)

  • Avoid grapefruit juice

  • Report muscle pain or dark urine (rhabdomyolysis risk)

  • Monitor liver enzymes as prescribed

9. Beta Blockers (e.g., Metoprolol, Propranolol)

• Class: Beta-adrenergic antagonists

• MOA: Block beta-1 (and sometimes beta-2) receptors → decrease heart rate, decrease contractility, decrease blood pressure

• Therapeutic Uses: Hypertension, heart failure, MI, angina, dysrhythmias, migraine prevention

• Side Effects:

  • Bradycardia, hypotension

  • Fatigue, depression, dizziness

  • Bronchospasm (non-selective only)

• Patient Education:

  • Do not stop abruptly — risk of rebound hypertension/angina

  • Monitor heart rate & blood pressure at home

  • Caution in diabetics due to potential for hypoglycemia masking

  • Report shortness of breath or weight gain (signs of CHF)

10. ACE Inhibitors (e.g., Lisinopril, Enalapril)

• Class: Angiotensin-Converting Enzyme (ACE) Inhibitors

• MOA: Blocks conversion of angiotensin I to angiotensin II → vasodilation, decreased aldosterone → decreased blood pressure

• Therapeutic Uses: Hypertension, heart failure, MI, diabetic nephropathy

• Side Effects:

  • Dry cough (common!)

  • Hyperkalemia

  • Hypotension

  • Angioedema (life-threatening)

• Patient Education:

  • Report facial swelling or difficulty breathing immediately

  • Do not use salt substitutes (contain potassium)

  • Monitor blood pressure and potassium levels

  • Change positions slowly

11. Calcium Channel Blockers (e.g., Diltiazem, Verapamil)

• Class: Nondihydropyridine calcium channel blockers

• MOA: Block calcium entry into cardiac and smooth muscle cells → decrease heart rate, decrease contractility, decrease blood pressure

• Therapeutic Uses: Hypertension, angina, atrial fibrillation/flutter

• Side Effects:

  • Bradycardia, hypotension

  • Peripheral edema

  • Constipation (especially verapamil)

• Patient Education:

  • Avoid grapefruit juice

  • Monitor blood pressure and heart rate

12. Digoxin

• Class: Cardiac glycoside

• MOA: Increases contractility (positive inotrope); slows conduction through AV node (decreases heart rate)

• Therapeutic Uses: Heart failure, atrial fibrillation

• Side Effects:

  • Digoxin toxicity: nausea, vomiting, vision changes (yellow/green halos), confusion, bradycardia

  • Dysrhythmias

• Patient Education:

  • Take pulse before dose — hold if heart rate is less than 60 bpm

  • Report nausea, vision changes, or confusion

  • Avoid taking with antacids (decreases absorption)

  • Monitor potassium — hypokalemia increases toxicity risk

13. Diuretics (General)

• Class: Loop (furosemide), Thiazide (HCTZ), Potassium-sparing (spironolactone)

• MOA: Increase excretion of sodium and water via kidneys → decrease blood volume and blood pressure

• Therapeutic Uses: Hypertension, edema, heart failure, fluid overload

• Side Effects:

  • Dehydration

  • Electrolyte imbalances (Potassium, Sodium, Magnesium)

  • Dizziness, hypotension

  • Spironolactone: gynecomastia, hyperkalemia

• Patient Education:

  • Take in the morning (avoid nocturia)

  • Monitor weight and electrolytes

  • Loop/Thiazide: increase potassium-rich foods

  • Spironolactone: avoid potassium supplements

14. Anticoagulants (e.g., Heparin, Warfarin, Enoxaparin)

• Class: Blood thinners

• MOA:

  • Heparin: Activates antithrombin III → inactivates thrombin and factor Xa

  • Warfarin: Inhibits vitamin K-dependent clotting factors

  • Enoxaparin (Lovenox): Low-molecular-weight heparin; mainly inhibits factor Xa

• Therapeutic Uses: DVT/PE prevention, stroke prevention in atrial fibrillation, post-op clot prevention

• Side Effects:

  • Bleeding

  • Heparin: thrombocytopenia (HIT)

  • Warfarin: narrow therapeutic range, teratogenic

• Patient Education:

  • Monitor for signs of bleeding (bruises, black stools)

  • Heparin: monitor aPTT; antidote = protamine sulfate

  • Warfarin: monitor INR (goal 2–3); antidote = vitamin K

  • Avoid NSAIDs, alcohol, and sudden diet changes in vitamin K intake

15. Insulin

• Class: Antidiabetic hormone

• MOA: Promotes glucose uptake into cells, especially muscle and fat; inhibits glucose production in liver

• Therapeutic Uses: Type 1 & 2 diabetes, DKA, hyperkalemia (in emergencies)

• Side Effects:

  • Hypoglycemia (most common): sweating, shaking, confusion

  • Weight gain

  • Lipodystrophy at injection site

• Patient Education:

  • Rotate injection sites

  • Match rapid-acting insulin with meals (must eat!)

  • Long-acting insulins (e.g., glargine) have no peak → do not skip doses!

  • Store unopened vials in fridge; opened vials at room temperature for 28 days

  • Carry a source of fast sugar (juice, glucose tabs)

16. Oral Antidiabetic Drugs (General)

• Class & Examples:

  • Biguanides: Metformin

  • Sulfonylureas: Glipizide, Glyburide

  • DPP-4 inhibitors: Sitagliptin

• MOA:

  • Metformin: Decreases hepatic glucose production, increases insulin sensitivity

  • Sulfonylureas: Stimulate pancreas to release insulin

  • DPP-4 inhibitors: Increase incretin → increase insulin, decrease glucagon

• Therapeutic Uses: Type 2 diabetes (not for Type 1)

• Side Effects:

  • Metformin: GI upset, lactic acidosis (BBW)

  • Sulfonylureas: Hypoglycemia, weight gain

• Patient Education:

  • Metformin: Do not take 48 hours before/after contrast dye

  • Report muscle pain or fatigue (sign of lactic acidosis)

  • Avoid alcohol

  • Take with food to reduce GI upset

17. Nitroglycerin

• Class: Organic nitrate, antianginal

• MOA: Vasodilates veins > arteries → decrease preload and afterload → decrease oxygen demand

• Therapeutic Uses: Acute angina, prevention of chest pain, heart failure with MI

• Side Effects:

  • Headache (very common), hypotension, reflex tachycardia, dizziness

  • Tolerance with long-term use

• Patient Education:

  • Sit or lie down before taking

  • Sublingual tablets: do not chew or swallow; may take every 5 minutes up to 3 doses

  • Keep in original dark container; expires after 6 months

  • Avoid erectile dysfunction drugs (PDE5 inhibitors) → risk of severe hypotension

  • Remove transdermal patches at night to prevent tolerance

18. Permethrin

• Class: Scabicide/Pediculicide

• MOA: Neurotoxin that paralyzes and kills lice and scabies mites by disrupting sodium channels in nerve cells

• Therapeutic Uses: Treatment of lice (head/body) and scabies

• Side Effects: Mild burning, stinging, itching, redness at application site

• Patient Education:

  • Apply topically to clean, dry skin or scalp

  • Leave on for 8–14 hours before washing off

  • Repeat treatment in 1 week if needed (eggs may survive)

  • Wash bedding, clothing in hot water to prevent reinfestation

19. Isotretinoin (Accutane)

• Class: Retinoid (Vitamin A derivative)

• MOA: Reduces sebaceous gland size and sebum production; inhibits P. acnes bacteria and inflammation

• Therapeutic Uses: Severe nodular acne unresponsive to other therapies

• Side Effects:

  • Teratogenicity (Black Box Warning) – severe birth defects

  • Dry skin, lips, eyes; muscle/joint pain; mood changes

  • Liver enzyme elevations, hyperlipidemia

• Patient Education:

  • Two forms of birth control required during and 1 month after therapy

  • Avoid Vitamin A supplements, alcohol, and donating blood

20. Allopurinol

• Class: Xanthine oxidase inhibitor

• MOA: Inhibits uric acid formation → lowers serum uric acid

• Therapeutic Uses: Chronic gout, kidney stones, tumor lysis syndrome

• Side Effects:

  • Rash (including Stevens-Johnson syndrome), GI upset

  • Hepatotoxicity, bone marrow suppression (rare)

• Patient Education:

  • Take with food to prevent GI upset

  • Increase fluids to help prevent kidney stones

  • May take several weeks to see effects

  • Do not start during acute gout attack

21. Timolol (Timoptic)

• Class: Beta-blocker (non-selective), ophthalmic

• MOA: Reduces intraocular pressure by decreasing aqueous humor production

• Therapeutic Uses: Open-angle glaucoma, ocular hypertension

• Side Effects:

  • Burning/stinging in eye

  • Systemic: bradycardia, bronchospasm (rare if absorbed)

• Patient Education:

  • Wait 5 minutes between eye drops if using multiple types

  • Press inner canthus (lacrimal duct) after instillation to prevent systemic absorption

  • Do not touch the dropper tip to the eye or any surface

22. Methotrexate

• Class: Antimetabolite, folic acid analog, immunosuppressant

• MOA: Inhibits dihydrofolate reductase → blocks DNA synthesis → suppresses immune cell replication

• Therapeutic Uses: Cancer (leukemia, lymphoma), rheumatoid arthritis, ectopic pregnancy, psoriasis

• Side Effects:

  • Bone marrow suppression (decreased RBC, WBC, platelets)

  • Hepatotoxicity

  • GI upset, mouth ulcers (stomatitis)

  • Fetal death/congenital anomalies (teratogenic)

• Patient Education:

  • Take folic acid supplements to reduce side effects

  • Avoid alcohol (increases liver risk)

  • Report bleeding, fatigue, or infection

  • Use 2 forms of birth control, avoid pregnancy for 6 months after therapy

23. General Cancer Drug Considerations

⚠️ High-risk & cytotoxic drugs:

Bone Marrow Suppression

• Decreased WBC → infection risk

• Decreased Platelets → bleeding risk

• Decreased RBC → fatigue/anemia

• 🔍 Monitor CBC regularly

• 🧼 Practice neutropenic precautions

Other Major Considerations

• GI toxicity: Nausea/Vomiting, stomatitis → antiemetics, soft diet, oral hygiene

• Alopecia: Hair loss is temporary

• Fertility risk: May cause infertility — offer counseling

• Handling precautions: Use gloves/gown — some drugs are vesicants (cause tissue damage)

🧠 KEY Nursing Priorities:

• Monitor for fever/infection, mouth sores, bleeding

• Encourage rest & high-protein diet

• Avoid live vaccines

• Educate about body image changes

24. Oral Contraceptives (Combined Estrogen-Progestin)

• Class: Hormonal contraceptive

• MOA: Suppresses ovulation by inhibiting FSH & LH, thickens cervical mucus, alters endometrium

• Therapeutic Uses: Prevent pregnancy, regulate periods, acne, PCOS

• Side Effects:

  • Nausea, breast tenderness, weight changes

  • Increased risk of blood clots, stroke, MI (especially in smokers >35)

• Patient Education:

  • Take at the same time every day

  • Use backup contraception if missed doses

  • Report leg pain, chest pain, shortness of breath (DVT/PE signs)

  • Avoid smoking

25. Oxytocin (Pitocin)

• Class: Hormone; uterine stimulant

• MOA: Stimulates uterine smooth muscle → induces labor and controls postpartum bleeding

• Therapeutic Uses:

  • Induce or augment labor

  • Control postpartum hemorrhage

• Side Effects:

  • Uterine rupture (especially with high doses or prior C-section)

  • Fetal distress (decreased oxygen)

  • Water intoxication (if prolonged infusion)

• Patient Education/Nursing Tips:

  • Continuous fetal and contraction monitoring

  • Stop infusion if contractions are too frequent or fetal distress signs occur

  • Administer via IV pump — titrate carefully

26. Folic Acid (Vitamin B9)

• Class: Water-soluble vitamin

• MOA: Required for DNA/RNA synthesis, cell division, neural tube development in fetus

• Therapeutic Uses:

  • Prevent neural tube defects (spina bifida)

  • Treat folic acid deficiency anemia

• Side Effects: None significant at normal doses

• Patient Education:

  • Take before pregnancy and during the 1st trimester (at least 400–800 mcg/day)

  • Found in leafy greens, fortified grains

  • Often combined in prenatal vitamins

27. Magnesium Sulfate

• Class: Electrolyte, anticonvulsant, tocolytic

• MOA: Depresses CNS and uterine activity; blocks neuromuscular transmission

• Therapeutic Uses:

  • Prevent seizures in preeclampsia/eclampsia

  • Preterm labor (tocolytic)

  • Treat hypomagnesemia

• Side Effects:

  • Flushing, hypotension, bradycardia

  • Respiratory depression, muscle weakness

  • Decreased deep tendon reflexes (toxicity)

• Patient Education/Nursing Tips:

  • Monitor respiratory rate, reflexes, urine output

  • Antidote: Calcium gluconate

  • Administer via IV pump; monitor closely

28. Lidocaine

• Class: Local anesthetic & Class IB antidysrhythmic

• MOA: Blocks sodium channels in neurons and cardiac cells → reduces pain or abnormal electrical conduction

• Therapeutic Uses:

  • Local anesthesia

  • Ventricular dysrhythmias (VT, VF)

• Side Effects:

  • CNS effects: confusion, tremor, seizures (toxicity)

  • Dysrhythmias, hypotension

  • Respiratory depression if systemic toxicity

• Note: Lipid rescue may be used as antidote for toxicity

29. Sildenafil (Viagra)

• Class: PDE-5 inhibitor

• MOA: Inhibits phosphodiesterase-5 → increases nitric oxide → vasodilation → improved penile blood flow

• Therapeutic Uses: Erectile dysfunction, pulmonary arterial hypertension

• Side Effects:

  • Headache, flushing, nasal congestion

  • Hypotension (especially if combined with nitrates)

  • Vision disturbances (blue-tinged vision)

• Patient Education:

  • Do NOT take with nitrates → risk of severe hypotension

  • Take 30–60 minutes before sexual activity

  • Report chest pain or sudden vision/hearing changes

  • Avoid alcohol

30. Finasteride

• Class: 5-alpha-reductase inhibitor

• MOA: Inhibits conversion of testosterone to DHT → shrinks prostate tissue and promotes hair growth

• Therapeutic Uses:

  • Benign prostatic hyperplasia (BPH)

  • Male pattern baldness (lower dose)

• Side Effects:

  • Decreased libido, erectile dysfunction

  • Gynecomastia

  • Can harm male fetus if handled during pregnancy

• Patient Education:

  • Pregnant women should not touch crushed/broken tablets

31. Donepezil (Aricept)

• Class: Cholinesterase inhibitor

• MOA: Prevents breakdown of acetylcholine → improves communication in neurons

• Therapeutic Uses: Alzheimer’s disease (mild to moderate stages)

• Side Effects:

  • GI upset (nausea, diarrhea), insomnia

  • Bradycardia, dizziness, fainting

• Patient Education:

  • Take at bedtime to reduce nausea

  • Not a cure — only slows symptoms

  • Monitor heart rate — report dizziness or fainting

  • Effects may fade with disease progression

32. Propofol

• Class: General anesthetic

• MOA: Enhances GABA activity → CNS depression → sedation and hypnosis

• Therapeutic Uses: Induction and maintenance of anesthesia or sedation (e.g., ICU intubation)

• Side Effects:

  • Hypotension, bradycardia

  • Respiratory depression

  • Propofol infusion syndrome (rare): metabolic acidosis, rhabdomyolysis

• Patient Education/Nursing Tips:

  • Only used in monitored settings (ICU, OR)

  • Monitor airway, vitals closely

  • Lipid-based → check for egg/soy allergies

  • Risk of bacterial growth — discard open vials after 6 hours

33. Cyclobenzaprine (Flexeril)

• Class: Centrally acting skeletal muscle relaxant

• MOA: Reduces tonic somatic motor activity via CNS sedation (brainstem level)

• Therapeutic Uses: Short-term treatment of muscle spasms

• Side Effects:

  • Drowsiness, dizziness

  • Dry mouth, constipation

  • CNS depression (especially with alcohol/benzodiazepines)

• Patient Education:

  • Avoid driving or alcohol

  • Short-term use only (2–3 weeks)

  • Take at night if sedating

  • Report confusion or difficulty urinating

34. Diphenhydramine (Benadryl)

• Class: First-generation antihistamine (H1 blocker)

• MOA: Blocks histamine receptors → reduces allergic symptoms

• Therapeutic Uses: Allergies, itching, insomnia, motion sickness, mild Parkinsonism

• Side Effects:

  • Drowsiness, dry mouth, dizziness

  • Urinary retention, constipation

  • Paradoxical excitement in children

• Patient Education:

  • Avoid alcohol and other sedatives

  • Avoid driving until effects are known

  • Can be used short-term for sleep, but not long-term

35. Dextromethorphan

• Class: Antitussive (cough suppressant)

• MOA: Suppresses cough reflex by acting on CNS (medulla); non-opioid

• Therapeutic Uses: Dry, nonproductive cough

• Side Effects:

  • Drowsiness, dizziness

  • GI upset

  • High doses = hallucinations or euphoria ("Robo-tripping")

• Patient Education:

  • Do not use with MAOIs (can cause serotonin syndrome)

  • Not recommended for children under 4 years

  • Do not exceed recommended dose

36. Albuterol

• Class: Short-acting beta-2 adrenergic agonist (SABA)

• MOA: Stimulates beta-2 receptors in bronchial smooth muscle → bronchodilation

• Therapeutic Uses: Acute asthma attack, exercise-induced bronchospasm

• Side Effects:

  • Tachycardia, tremors

  • Nervousness, insomnia

  • Hypokalemia (rare)

• Patient Education:

  • Use before inhaled corticosteroid (if prescribed both)

  • Wait 1 minute between puffs

  • Carry as rescue inhaler

  • Overuse = decreased effectiveness

37. Beclomethasone

• Class: Inhaled corticosteroid (ICS)

• MOA: Reduces airway inflammation and suppresses immune response

• Therapeutic Uses: Asthma (maintenance), allergic rhinitis

• Side Effects:

  • Oral thrush (candidiasis)

  • Hoarseness, sore throat

  • Headache

• Patient Education:

  • Rinse mouth after each use

  • Not for acute attacks

  • Use daily for prevention

  • Use bronchodilator first, then steroid