Pharmacology Reference: 10 Major Drug Categories

1. Antidiabetic Drugs

Insulin

Oral Hypoglycemic Agents (OHAs)

• Sulfonylureas (1st gen: Tolbutamide, Chlorpropamide; 2nd gen: Glibenclamide/Glyburide, Glipizide, Gliclazide, Glimepiride) - close K-ATP channels on beta cells -> depolarization -> insulin release
• Meglitinides (Repaglinide, Nateglinide) - same mechanism, shorter acting, taken with meals

• Biguanides (Metformin) - activates AMPK, reduces hepatic glucose output, increases peripheral uptake; does NOT cause hypoglycemia; drug of choice in type 2 DM
• Thiazolidinediones / Glitazones (Pioglitazone, Rosiglitazone) - PPAR-gamma agonists; improve insulin sensitivity; risk: fluid retention, osteoporosis, bladder cancer (Pioglitazone)

• Acarbose, Miglitol, Voglibose - delay carbohydrate absorption in gut; no hypoglycemia; SE: flatulence, diarrhea

• Exenatide, Liraglutide, Dulaglutide, Semaglutide - increase insulin, suppress glucagon, delay gastric emptying, promote weight loss
• Benefit: CV protection (Liraglutide, Semaglutide)

• Sitagliptin, Vildagliptin, Saxagliptin, Alogliptin, Linagliptin - inhibit DPP-4 (which degrades GLP-1); weight neutral; SE: nasopharyngitis, pancreatitis risk

• Dapagliflozin, Empagliflozin, Canagliflozin - block glucose reabsorption in proximal tubule; cause glycosuria; CV and renal protection; SE: UTI, genital mycosis, DKA

• Pramlintide - slows gastric emptying, suppresses glucagon

2. Antihypertensive Drugs

Classification

• Thiazides (Hydrochlorothiazide, Chlorthalidone) - first-line for hypertension
• Loop diuretics (Furosemide) - mainly for heart failure with HTN
• K-sparing (Spironolactone, Amiloride)

• Non-selective: Propranolol, Nadolol
• Cardioselective (beta-1): Atenolol, Metoprolol, Bisoprolol
• With alpha-blocking: Carvedilol, Labetalol (preferred in pregnancy hypertension)
• Mechanism: reduce heart rate, cardiac output, renin release

• Dihydropyridines (vascular selective): Amlodipine, Nifedipine, Felodipine - first-line
• Non-dihydropyridines: Verapamil (also anti-arrhythmic), Diltiazem - reduce HR + BP

• Ramipril, Enalapril, Lisinopril, Captopril - block conversion of Ang I to Ang II; nephroprotective in diabetes; CI in pregnancy; SE: dry cough, hyperkalemia, angioedema

• Losartan, Valsartan, Telmisartan, Olmesartan - block AT1 receptor; similar to ACEi without cough; CI in pregnancy

• Clonidine (alpha-2 agonist), Methyldopa (drug of choice in pregnancy hypertension)

• Prazosin, Doxazosin, Terazosin - also used in BPH; SE: first-dose hypotension

• Hydralazine (arteriolar), Minoxidil (arteriolar, severe HTN/alopecia)
• Sodium Nitroprusside (hypertensive emergencies - both arterial and venous)

• Non-black: ACEi/ARB or CCB or Thiazide
• Black population: CCB or Thiazide (ACEi less effective)
• With diabetes/CKD: ACEi or ARB preferred

3. Diuretics

Classification by Site of Action

• Heart failure: Loop diuretics
• HTN: Thiazides
• Cerebral edema: Mannitol
• Primary aldosteronism: Spironolactone
• Nephrogenic DI: Thiazides (paradoxical use)

4. Antiepileptic Drugs (AEDs)

Classification by Generation

• Phenytoin - Na+ channel blocker; zero-order kinetics; SE: gingival hyperplasia, hirsutism, ataxia, teratogen (fetal hydantoin syndrome), Stevens-Johnson syndrome
• Phenobarbitone - enhances GABA-A; enzyme inducer; sedation
• Carbamazepine - Na+ channel blocker; drug of choice for partial seizures, trigeminal neuralgia; SE: diplopia, aplastic anemia, SIADH
• Valproate (Sodium Valproate) - broad spectrum; multiple mechanisms (Na+ channel, GABA, T-type Ca2+ block); drug of choice for absence + tonic-clonic; SE: hepatotoxicity, teratogen (neural tube defects), weight gain, tremor
• Ethosuximide - T-type Ca2+ channel block; drug of choice for absence seizures

• Lamotrigine - Na+ channel blocker; broad spectrum; safe in pregnancy (relatively); SE: rash, SJS
• Levetiracetam - binds SV2A protein; minimal drug interactions; used in refractory epilepsy
• Topiramate - multiple mechanisms; also used in migraine prophylaxis; SE: cognitive dulling, kidney stones, weight loss
• Gabapentin / Pregabalin - bind alpha-2-delta subunit of voltage-gated Ca2+ channels; also used in neuropathic pain, fibromyalgia
• Oxcarbazepine - like Carbamazepine but fewer interactions, less aplastic anemia risk
• Vigabatrin - irreversible GABA transaminase inhibitor; used in West syndrome; SE: visual field defects
• Tiagabine - GABA reuptake inhibitor
• Zonisamide - Na+/T-Ca2+ blocker

5. Antimalarial Drugs

Classification

• Chloroquine - 4-aminoquinoline; MOA: accumulates in parasite food vacuole, inhibits heme polymerization; drug of choice for P. vivax and sensitive P. falciparum; SE: retinopathy, pruritus, GI upset
• Quinine - oldest; MOA: similar to chloroquine; used in severe/complicated malaria; SE: cinchonism (tinnitus, headache), blackwater fever, hypoglycemia
• Artemisinin derivatives (Artesunate, Artemether, Dihydroartemisinin) - fastest acting; generate free radicals that damage parasite; drug of choice for severe P. falciparum (IV Artesunate); used as ACT (artemisinin-based combination therapy)
• Mefloquine - used for chloroquine-resistant P. falciparum; SE: neuropsychiatric effects
• Lumefantrine - used in ACT combination (Artemether + Lumefantrine = Coartem)
• Atovaquone-Proguanil (Malarone) - inhibits mitochondrial electron transport; used for chemoprophylaxis and treatment

• Primaquine - 8-aminoquinoline; kills hypnozoites of P. vivax and P. ovale (prevents relapse); also gametocidal; SE: hemolytic anemia in G6PD deficiency (must test G6PD first)
• Tafenoquine - newer 8-aminoquinoline; single-dose radical cure for P. vivax

• Primaquine (especially for P. falciparum)
• Artemisinins

• Proguanil, Pyrimethamine - dihydrofolate reductase inhibitors; prevent development in liver
• Doxycycline - chemoprophylaxis

• Artemether + Lumefantrine
• Artesunate + Amodiaquine
• Artesunate + Mefloquine
• Artesunate + Sulfadoxine-Pyrimethamine

6. Antitubercular Drugs (ATT)

First-Line Drugs (RIPE / HRZE)

Second-Line Drugs

• Fluoroquinolones: Levofloxacin, Moxifloxacin (inhibit DNA gyrase)
• Injectable aminoglycosides: Amikacin, Kanamycin, Capreomycin
• Newer agents: Bedaquiline (ATP synthase inhibitor), Linezolid, Delamanid, Pretomanid (for MDR/XDR-TB)
• Older 2nd line: Ethionamide, Cycloserine, PAS (Para-aminosalicylic acid)

Standard Regimens (RNTCP/WHO)

• New pulmonary TB: 2HRZE / 4HR (intensive phase 2 months, continuation 4 months)
• MDR-TB: Longer regimens with fluoroquinolones + injectables (18-24 months)

Drug Resistance

• MDR-TB: Resistant to Rifampicin + Isoniazid
• XDR-TB: MDR + resistant to fluoroquinolone + any 2nd-line injectable

7. Antibiotics - Classification

By Mechanism of Action

• Beta-lactams:
  • Penicillins: Penicillin G (natural), Amoxicillin, Ampicillin (aminopenicillins), Piperacillin (antipseudomonal), Cloxacillin/Flucloxacillin (penicillinase-resistant)
  • Cephalosporins: 1st (Cefazolin, Cefalexin), 2nd (Cefuroxime, Cefaclor), 3rd (Ceftriaxone, Cefotaxime, Ceftazidime), 4th (Cefepime), 5th (Ceftaroline - anti-MRSA)
  • Carbapenems: Imipenem-Cilastatin, Meropenem, Doripenem, Ertapenem (broadest spectrum)
  • Monobactams: Aztreonam (gram-negative only; safe in penicillin allergy)
  • Beta-lactamase inhibitors: Clavulanate, Sulbactam, Tazobactam (combined with penicillins)
• Glycopeptides: Vancomycin, Teicoplanin (inhibit transglycosylation; used for MRSA, C. diff)

• Polymyxins: Colistin (Polymyxin E), Polymyxin B - last resort for gram-negative MDR; SE: nephrotoxicity, neurotoxicity
• Daptomycin - for gram-positive (MRSA, VRE); not for pneumonia (inactivated by surfactant)

• 30S Inhibitors:
  • Aminoglycosides: Gentamicin, Amikacin, Tobramycin, Streptomycin - bactericidal; SE: ototoxicity, nephrotoxicity
  • Tetracyclines: Tetracycline, Doxycycline, Minocycline, Tigecycline - bacteriostatic; broad spectrum; SE: discoloration of teeth (children), photosensitivity
• 50S Inhibitors:
  • Macrolides: Erythromycin, Azithromycin, Clarithromycin - bacteriostatic; atypicals, pertussis
  • Chloramphenicol - broad spectrum; SE: aplastic anemia, gray baby syndrome
  • Lincosamides: Clindamycin - anaerobes, bone/joint infections; SE: pseudomembranous colitis
  • Oxazolidinones: Linezolid - MRSA, VRE; SE: serotonin syndrome, myelosuppression
  • Streptogramins: Quinupristin-Dalfopristin (Synercid) - VRE, MRSA

• Fluoroquinolones: Ciprofloxacin, Levofloxacin, Moxifloxacin - inhibit DNA gyrase (topoisomerase II/IV); SE: tendinopathy, QT prolongation, cartilage damage (children)
• Rifampicin - RNA polymerase inhibitor (also ATT)
• Metronidazole / Tinidazole - form reactive intermediates that damage DNA; anaerobes + protozoa
• Nitrofurantoin - reactive intermediates; urinary tract infections only

• Sulfonamides: Sulfamethoxazole - inhibit dihydropteroate synthetase (DHPS)
• Trimethoprim - inhibits dihydrofolate reductase (DHFR)
• Co-trimoxazole (TMP-SMX) = sequential block; used for PCP, UTI, Nocardia, Pneumocystis

8. NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)

Mechanism

• COX-1: constitutive; protects gastric mucosa, platelet aggregation (TXA2)
• COX-2: inducible; mediates inflammation, pain, fever; also renal and vascular effects

Classification

• Salicylates: Aspirin (irreversible COX inhibitor; low dose -> anti-platelet; high dose -> anti-inflammatory)
• Propionic acid derivatives: Ibuprofen, Naproxen, Ketoprofen
• Acetic acid derivatives: Indomethacin (most potent; used to close patent ductus arteriosus), Diclofenac, Ketorolac (parenteral), Sulindac, Etodolac
• Fenamates: Mefenamic acid, Meclofenamate
• Oxicams: Piroxicam, Meloxicam (mild COX-2 preference)
• Pyranoacetic acid: Ketorolac

• Celecoxib, Etoricoxib, Parecoxib - less GI toxicity; increased CV risk (thrombotic events); Rofecoxib, Valdecoxib withdrawn due to CV events

• Nimesulide, Meloxicam, Diclofenac (slightly COX-2 preferential)

• Paracetamol (Acetaminophen) - central COX inhibition + endocannabinoid pathway; no peripheral anti-inflammatory; hepatotoxic in overdose (treat with N-acetylcysteine)

Key Side Effects

• GI ulceration, bleeding (COX-1 inhibition - gastric protection lost)
• Renal: reduced GFR, fluid retention, acute renal failure
• Aspirin: Reye's syndrome in children, salicylism (tinnitus, hyperventilation)
• Platelet dysfunction (except COX-2 selective - don't affect platelets)

9. Antiasthma Drugs

Classification

1. Beta-2 Agonists
   • Short-Acting (SABA - Relievers): Salbutamol (Albuterol), Terbutaline - onset 5 min, duration 4-6 hr; used for acute attacks
   • Long-Acting (LABA - Controllers): Salmeterol, Formoterol - duration 12 hr; never use alone in asthma (must combine with ICS); Formoterol has fast onset (also usable as reliever)
   • Ultra-LABA: Indacaterol, Vilanterol (once daily; used in COPD)
2. Anticholinergics (Muscarinic antagonists)
   • Short-Acting (SAMA): Ipratropium - useful in COPD and acute asthma (added to SABA)
   • Long-Acting (LAMA): Tiotropium, Aclidinium, Glycopyrronium - mainly COPD; tiotropium also used in severe asthma
3. Methylxanthines
   • Theophylline, Aminophylline - inhibit phosphodiesterase (increase cAMP); bronchodilator + mild anti-inflammatory; narrow therapeutic index; SE: nausea, arrhythmias, seizures at toxic levels

1. Inhaled Corticosteroids (ICS) - mainstay of long-term asthma control
   • Beclomethasone, Budesonide, Fluticasone, Ciclesonide, Mometasone
   • SE: oral candidiasis (rinse mouth after use), hoarseness, adrenal suppression (high dose)
2. Leukotriene Modifiers
   • Montelukast, Zafirlukast (CysLT1 receptor antagonists) - oral; useful in aspirin-sensitive asthma, exercise-induced asthma, allergic rhinitis
   • Zileuton (5-LOX inhibitor) - prevents leukotriene synthesis
3. Mast Cell Stabilizers
   • Sodium Cromoglycate (Cromolyn), Nedocromil - prophylaxis only; not for acute attacks
4. Biologics (Monoclonal antibodies) for severe asthma
   • Anti-IgE: Omalizumab (binds IgE) - allergic asthma
   • Anti-IL-5: Mepolizumab, Reslizumab (reduce eosinophils) - eosinophilic asthma
   • Anti-IL-5R: Benralizumab
   • Anti-IL-4R/IL-13: Dupilumab
   • Anti-TSLP: Tezepelumab (broadest indication)
5. Systemic Corticosteroids - Prednisolone, Methylprednisolone (acute severe attacks, step-up therapy)

• Step 1: SABA as needed (or low-dose ICS-Formoterol as reliever)
• Step 2: Low-dose ICS + SABA
• Step 3: Low-dose ICS-LABA
• Step 4: Medium-dose ICS-LABA
• Step 5: High-dose ICS-LABA + add-ons; consider biologic

10. Drugs for Peptic Ulcer

Classification

1. Proton Pump Inhibitors (PPIs) - most effective acid suppressants
   • Omeprazole, Pantoprazole, Lansoprazole, Rabeprazole, Esomeprazole (S-isomer of Omeprazole), Dexlansoprazole
   • Mechanism: Irreversibly inhibit H+/K+-ATPase (proton pump) on parietal cells
   • SE: hypomagnesemia (long-term), C. diff infection, osteoporosis, B12 deficiency, drug interactions (Clopidogrel - CYP2C19 competition with Omeprazole)
2. H2-Receptor Antagonists (H2RA)
   • Ranitidine (withdrawn - NDMA contamination), Famotidine, Cimetidine, Nizatidine
   • Block H2 receptors on parietal cells; reduce basal and nocturnal acid; faster onset than PPIs
   • Cimetidine: many drug interactions (enzyme inhibitor), gynecomastia, impotence
3. Anticholinergics (historical) - Pirenzepine (M1 selective); reduces acid + GI motility
4. Antacids - symptom relief only; Aluminum hydroxide (constipating), Magnesium hydroxide (laxative), CaCO3, Sodium bicarbonate

1. Sucralfate - polymerizes in acid; forms sticky coat over ulcer base; stimulates prostaglandin + mucus secretion; minimal systemic absorption; take on empty stomach; binds many drugs (separate by 2 hr)
2. Bismuth compounds (Bismuth subsalicylate, Tripotassium dicitratobismuthate/De-Nol) - coats ulcer, bactericidal against H. pylori; used in H. pylori eradication regimens; SE: black stools, tongue blackening
3. Misoprostol - PGE1 analog; inhibits acid secretion + stimulates mucus/bicarbonate; used to prevent NSAID-induced ulcers; CI: pregnancy (causes abortion - used in MTP)

• Metoclopramide (D2 antagonist), Domperidone, Itopride

Sources: Goodman & Gilman's The Pharmacological Basis of Therapeutics; Goldman-Cecil Medicine; Brenner & Rector's The Kidney; Ganong's Review of Medical Physiology; Adams & Victor's Principles of Neurology.