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KD Tripathi pharmacology important drug classifications undergraduate exam

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Important Drug Classifications in Pharmacology

(KD Tripathi Style - UG Exam Focus)

Below are the most exam-important drug classifications, organized by system. These are the ones KDT emphasizes and examiners repeatedly ask.

1. AUTONOMIC NERVOUS SYSTEM DRUGS

Adrenergic Agonists (Sympathomimetics)

Type	Mechanism	Drugs
Direct-acting	Act on adrenergic receptors	Adrenaline, Noradrenaline, Isoprenaline, Dobutamine, Salbutamol, Clonidine
Indirect-acting	Release stored NE	Amphetamine, Tyramine, Ephedrine (partial)
Mixed-acting	Both direct + indirect	Ephedrine, Dopamine

Receptor selectivity:

α1 selective: Phenylephrine, Methoxamine, Xylometazoline
α2 selective: Clonidine, Methyldopa (pro-drug), Brimonidine
β1 selective: Dobutamine, Metaraminol
β2 selective: Salbutamol, Terbutaline, Salmeterol, Formoterol, Ritodrine
Non-selective β: Isoprenaline
Non-selective α+β: Adrenaline (low dose α+β; high dose: α>β), Noradrenaline (α>β)
Dopamine: D1 > β1 > α1 (dose-dependent)

Adrenergic Antagonists (Sympatholytics)

Alpha-blockers:

Class	Drugs
Non-selective α (irreversible)	Phenoxybenzamine
Non-selective α (competitive)	Phentolamine, Tolazoline
Selective α1	Prazosin, Terazosin, Doxazosin, Tamsulosin
Selective α2	Yohimbine

Beta-blockers:

Class	Drugs
Non-selective β (no ISA)	Propranolol, Timolol, Nadolol, Sotalol
Non-selective β (with ISA)	Pindolol, Oxprenolol
Cardioselective β1 (no ISA)	Metoprolol, Atenolol, Bisoprolol, Esmolol
Cardioselective β1 (with ISA)	Acebutolol
α + β blocker	Labetalol, Carvedilol

Cholinergic Drugs

Cholinomimetics:

Class	Drugs
Choline esters (direct)	Acetylcholine, Carbachol, Bethanechol, Methacholine
Alkaloids (direct)	Muscarine, Pilocarpine, Arecoline
Anticholinesterases (indirect - reversible)	Physostigmine, Neostigmine, Pyridostigmine, Edrophonium
Anticholinesterases (indirect - irreversible)	Organophosphates: Malathion, Parathion, Tabun, DFP (Dyflos)

Anticholinergics (Muscarinic blockers):

Use	Drugs
General	Atropine, Hyoscine (Scopolamine), Homatropine
Antispasmodics (GI)	Dicyclomine, Propantheline, Glycopyrrolate
Anti-Parkinson	Trihexyphenidyl (Benzhexol), Biperiden, Procyclidine
Pre-anesthetic	Glycopyrrolate, Atropine
Bronchodilator	Ipratropium, Tiotropium

2. CNS DRUGS

Sedative-Hypnotics

Class	Drugs
Benzodiazepines (short-acting)	Triazolam, Oxazepam, Temazepam
Benzodiazepines (long-acting)	Diazepam, Chlordiazepoxide, Nitrazepam, Flurazepam
Barbiturates (ultra-short)	Thiopentone, Methohexitone
Barbiturates (short)	Pentobarbitone, Secobarbitone
Barbiturates (long)	Phenobarbitone
Z-drugs (non-BZD)	Zolpidem, Zopiclone, Zaleplon
Newer hypnotics	Melatonin, Ramelteon, Doxepin

Antiepileptics (KDT Classification)

Type of Seizure	Drug of Choice	Alternatives
Tonic-clonic (GTCS)	Sodium valproate, Phenytoin	Carbamazepine, Phenobarbitone
Absence (Petit mal)	Ethosuximide	Sodium valproate, Clonazepam
Myoclonic	Sodium valproate	Clonazepam, Levetiracetam
Focal/Partial	Carbamazepine	Phenytoin, Valproate, Lamotrigine
Status epilepticus	IV Diazepam / Lorazepam → Phenytoin → Phenobarbitone	Levetiracetam, Propofol
Febrile seizures	Diazepam (rectal/IV)	Phenobarbitone

Mechanism-based classification:

Na+ channel blockers: Phenytoin, Carbamazepine, Lamotrigine, Oxcarbazepine
GABA enhancers: Phenobarbitone, Benzodiazepines, Gabapentin, Vigabatrin, Tiagabine
T-type Ca2+ channel blockers: Ethosuximide
Multiple mechanisms (valproate): Na+ block + GABA ↑ + T-Ca2+ block

Antipsychotics (Neuroleptics)

Generation	Drugs
Typical / FGA (low potency)	Chlorpromazine, Thioridazine
Typical / FGA (high potency)	Haloperidol, Fluphenazine, Trifluoperazine
Atypical / SGA	Clozapine, Olanzapine, Risperidone, Quetiapine, Aripiprazole, Ziprasidone
Depot (long-acting)	Fluphenazine decanoate, Haloperidol decanoate, Risperidone microspheres

Antidepressants

Class	Drugs
TCAs	Imipramine, Amitriptyline, Clomipramine, Desipramine
SSRIs	Fluoxetine, Sertraline, Paroxetine, Escitalopram, Fluvoxamine
SNRIs	Venlafaxine, Duloxetine
MAOIs	Phenelzine, Tranylcypromine, Moclobemide (reversible - RIMA)
Atypicals	Mirtazapine (NaSSA), Bupropion (NDRI), Trazodone

Opioid Analgesics

Class	Drugs
Strong agonists (μ)	Morphine, Fentanyl, Methadone, Meperidine (Pethidine), Oxycodone
Moderate agonists	Codeine, Tramadol, Tapentadol, Dihydrocodeine
Mixed agonist-antagonist	Pentazocine (κ agonist/μ antagonist), Buprenorphine (partial μ agonist), Nalbuphine
Pure antagonists	Naloxone (short-acting), Naltrexone (long-acting), Methylnaltrexone (peripheral)

3. CARDIOVASCULAR DRUGS

Antihypertensives (KDT Classification)

Class	Drugs
Diuretics	Thiazides (Hydrochlorothiazide), Loop (Furosemide), K-sparing (Spironolactone, Amiloride)
ACE Inhibitors	Captopril (sulfhydryl), Enalapril, Lisinopril, Ramipril (carboxyl), Fosinopril (phosphinyl)
ARBs (sartans)	Losartan, Valsartan, Irbesartan, Telmisartan, Candesartan
CCBs - Dihydropyridines	Nifedipine, Amlodipine, Felodipine, Nimodipine
CCBs - Non-DHP	Verapamil (phenylalkylamine), Diltiazem (benzothiazepine)
β-blockers	Atenolol, Metoprolol, Propranolol
Central α2 agonists	Clonidine, Methyldopa, Moxonidine
Vasodilators	Hydralazine, Minoxidil, Diazoxide, Sodium nitroprusside
α1-blockers	Prazosin, Doxazosin, Terazosin

Antiarrhythmics - Vaughan-Williams Classification

(This is one of the most asked classifications in exams)

Class	Mechanism	Drugs
Ia	Na+ block (moderate) - slows phase 0, prolongs APD	Quinidine, Procainamide, Disopyramide
Ib	Na+ block (weak) - shortens phase 3 repolarization	Lidocaine, Mexiletine, Tocainide
Ic	Na+ block (strong) - markedly slows phase 0	Flecainide, Propafenone
II	β-blockade - slows SA/AV node	Propranolol, Esmolol, Metoprolol
III	K+ channel block - prolongs repolarization	Amiodarone, Sotalol, Dofetilide, Ibutilide
IV	Ca2+ channel block - slows SA/AV node	Verapamil, Diltiazem
Unclassified	Various	Digoxin, Adenosine, Atropine, Magnesium

Exam tips: Amiodarone has Class I + II + III + IV properties (all four classes). Sotalol = β-blocker (Class II) + K+ blocker (Class III). Quinidine causes cinchonism + torsades de pointes.

Antianginal Drugs

Class	Drugs	Use
Nitrates (short-acting)	GTN (sublingual/transdermal), ISDN	Acute attack
Nitrates (long-acting)	Isosorbide mononitrate (ISMN), Isosorbide dinitrate (ISDN oral)	Prophylaxis
β-blockers	Atenolol, Metoprolol	Stable angina
CCBs	Amlodipine, Verapamil, Diltiazem	Vasospastic angina
Others	Ranolazine (late Na+ current block), Ivabradine (If channel block), Trimetazidine (metabolic)	Refractory angina

Diuretics

Class	Site	Drugs
Osmotic	PCT + Loop of Henle	Mannitol, Urea, Glycerol
Carbonic anhydrase inhibitors	PCT	Acetazolamide
Loop diuretics	Thick ascending Loop of Henle	Furosemide, Bumetanide, Torasemide, Ethacrynic acid
Thiazides	DCT (early)	Hydrochlorothiazide, Chlorthalidone, Indapamide
K+-sparing (aldosterone antagonist)	CCD	Spironolactone, Eplerenone
K+-sparing (ENaC blockers)	CCD	Amiloride, Triamterene
Aquaretics (V2 receptor antagonists)	CCD	Tolvaptan, Conivaptan

4. ANTIMICROBIALS

Antibiotics by Mechanism

Mechanism	Drugs
Cell wall synthesis inhibitors	Penicillins, Cephalosporins, Carbapenems, Monobactams, Glycopeptides (Vancomycin), Bacitracin
Protein synthesis (30S)	Aminoglycosides (Streptomycin, Gentamicin, Amikacin), Tetracyclines
Protein synthesis (50S)	Macrolides (Erythromycin, Azithromycin, Clarithromycin), Chloramphenicol, Clindamycin, Linezolid
DNA gyrase inhibitors	Fluoroquinolones (Ciprofloxacin, Levofloxacin, Moxifloxacin)
RNA polymerase inhibitors	Rifampicin
Cell membrane disruptors	Polymyxin B, Colistin, Daptomycin
DNA damage	Metronidazole, Nitrofurantoin
Folate synthesis inhibitors	Sulfonamides, Trimethoprim

Cephalosporins (Generation-wise - very commonly asked)

Generation	Anti-gram -ve	Drugs
1st	Low	Cephalexin, Cefazolin, Cefadroxil
2nd	Moderate	Cefuroxime, Cefaclor, Cefoxitin
3rd	High	Cefotaxime, Ceftriaxone, Ceftazidime (anti-Pseudomonal)
4th	Very high + antipseudomonal	Cefepime
5th	MRSA active	Ceftaroline, Ceftobiprole

Antitubercular Drugs

Category	Drugs
First-line	Isoniazid (H), Rifampicin (R), Pyrazinamide (Z), Ethambutol (E), Streptomycin (S)
Second-line (MDR-TB)	Fluoroquinolones (Moxifloxacin, Levofloxacin), Amikacin, Capreomycin, Ethionamide, Cycloserine
Newer drugs	Bedaquiline, Delamanid, Pretomanid (BPaL regimen for XDR-TB)

Side effects (exam favorite):

Isoniazid → Peripheral neuropathy (prevented by pyridoxine B6), Hepatotoxicity, SLE-like
Rifampicin → Orange urine/secretions, Hepatotoxicity, Enzyme inducer
Pyrazinamide → Hyperuricemia, Hepatotoxicity
Ethambutol → Optic neuritis (retrobulbar), colour vision loss
Streptomycin → Ototoxicity (vestibular > cochlear), Nephrotoxicity

5. AUTACOIDS & ANTI-INFLAMMATORY DRUGS

NSAIDs - Classification

Class	Drugs
Salicylates	Aspirin, Sodium salicylate, Diflunisal
Propionic acid derivatives	Ibuprofen, Naproxen, Ketoprofen
Acetic acid derivatives	Indomethacin, Diclofenac, Ketorolac, Sulindac
Oxicams	Piroxicam, Meloxicam, Tenoxicam
Fenamates	Mefenamic acid, Flufenamic acid
Pyrazolone derivatives	Phenylbutazone, Oxyphenbutazone
Selective COX-2 inhibitors (coxibs)	Celecoxib, Etoricoxib, Parecoxib, Rofecoxib (withdrawn)
Para-aminophenol derivative	Paracetamol (Acetaminophen)

Histamine Antagonists

Generation	Sedation	Drugs
H1 - 1st generation (sedating)	Yes	Chlorpheniramine, Diphenhydramine, Promethazine, Cyclizine, Meclizine
H1 - 2nd generation (non-sedating)	No	Loratadine, Cetirizine, Fexofenadine, Desloratadine, Levocetirizine
H2 blockers	N/A	Cimetidine, Ranitidine, Famotidine, Nizatidine

6. ENDOCRINE PHARMACOLOGY

Insulin Types (Exam Classic)

Type	Onset	Peak	Duration	Examples
Rapid-acting	15 min	30-90 min	3-5 h	Lispro, Aspart, Glulisine
Short-acting (Regular)	30-60 min	2-3 h	6-8 h	Human Regular Insulin
Intermediate	1-2 h	4-6 h	12-18 h	NPH (Isophane)
Long-acting (peakless)	2-4 h	No peak	20-24 h	Glargine, Detemir
Ultra-long	6 h	No peak	42 h	Degludec

Oral Hypoglycemic Agents

Class	Mechanism	Drugs
Sulfonylureas (1st gen)	↑ Insulin secretion (K+ATP close)	Tolbutamide, Chlorpropamide, Glibenclamide
Sulfonylureas (2nd gen)	Same + more potent	Glipizide, Gliclazide, Glimepiride
Biguanides	↓ Hepatic gluconeogenesis, ↑ insulin sensitivity	Metformin
Thiazolidinediones (glitazones)	PPARγ agonist → ↑ insulin sensitivity	Pioglitazone, Rosiglitazone
Alpha-glucosidase inhibitors	Delay carb absorption	Acarbose, Miglitol, Voglibose
DPP-4 inhibitors (gliptins)	↑ GLP-1 → ↑ insulin, ↓ glucagon	Sitagliptin, Vildagliptin, Saxagliptin
GLP-1 agonists	↑ Insulin, ↓ glucagon, ↓ gastric emptying, weight loss	Exenatide, Liraglutide, Dulaglutide, Semaglutide
SGLT-2 inhibitors (gliflozins)	↑ Urinary glucose excretion	Dapagliflozin, Empagliflozin, Canagliflozin
Meglitinides (glinides)	↑ Insulin secretion (faster, shorter)	Repaglinide, Nateglinide

7. ANTICANCER DRUGS

Classification by Mechanism

Class	Drugs
Alkylating agents	Cyclophosphamide, Chlorambucil, Melphalan, Busulfan, Carmustine (BCNU), Cisplatin, Carboplatin
Antimetabolites - Folate antagonists	Methotrexate
Antimetabolites - Purine antagonists	6-Mercaptopurine (6-MP), 6-Thioguanine, Azathioprine
Antimetabolites - Pyrimidine antagonists	5-Fluorouracil (5-FU), Cytarabine (Ara-C), Gemcitabine, Capecitabine
Vinca alkaloids (microtubule inhibitors)	Vincristine, Vinblastine, Vinorelbine
Taxanes (microtubule stabilizers)	Paclitaxel, Docetaxel
Topoisomerase I inhibitors	Irinotecan, Topotecan
Topoisomerase II inhibitors	Etoposide, Teniposide, Doxorubicin, Daunorubicin
Antibiotics (anticancer)	Doxorubicin, Bleomycin, Dactinomycin, Mitomycin C
Targeted therapy - TKIs	Imatinib (BCR-ABL/CML), Gefitinib, Erlotinib (EGFR), Trastuzumab (HER2)
Hormonal agents	Tamoxifen (SERM, breast Ca), Anastrozole (aromatase inhibitor), Flutamide (anti-androgen)

8. KEY EXAM MNEMONICS FROM KDT

Drugs causing SLE-like syndrome: P-SHIM - Procainamide, Sulfonamides, Hydralazine, Isoniazid, Minocycline

Enzyme inducers (↑ CYP450): PC BRAS - Phenytoin, Carbamazepine, Barbiturates, Rifampicin, Alcohol (chronic), Smoking

Enzyme inhibitors (↓ CYP450): AICE-GEK - Amiodarone, Isoniazid, Cimetidine, Erythromycin, Grapefruit juice, Etoconazole, Ketoconazole

Teratogenic drugs (Category X / high risk):

Thalidomide, Warfarin, Methotrexate, Valproate, Phenytoin, Retinoids (Vitamin A), ACE inhibitors (2nd/3rd trimester), Aminoglycosides, Tetracyclines, Misoprostol, Diethylstilbestrol (DES)

Drugs safe in pregnancy (category B): Penicillins, Cephalosporins, Metronidazole (after 1st trimester), Paracetamol, Metformin, Labetalol, Methyldopa, Hydralazine

9. PHARMACOKINETICS CLASSIFICATION (Commonly Tested)

Parameter	High	Low
Plasma protein binding	Warfarin (99%), Phenytoin (90%), Diazepam (98%)	Digoxin (25%), Lithium (0%), Aminoglycosides (10%)
Volume of distribution (Vd)	Chloroquine (very high), Digoxin (7 L/kg), Amiodarone (60 L/kg)	Heparin, Mannitol (plasma only)
T1/2 (very long)	Amiodarone (40-55 days), Chloroquine (weeks), Digoxin (36 h)	Adenosine (10 seconds), Aspirin (20 min as acetylsalicylate)
Renal excretion (unchanged)	Aminoglycosides, Lithium, Metformin	Lidocaine, Propranolol (hepatic)

Sources: Goodman & Gilman's Pharmacological Basis of Therapeutics; Lippincott Illustrated Reviews: Pharmacology; Katzung's Basic & Clinical Pharmacology, 16th ed. These are equivalent reference standards to KD Tripathi's Essentials of Medical Pharmacology (9th ed.) for UG examination purposes.

Pro tip for exams: The examiner's most-asked topics from KDT are:

Vaughan-Williams antiarrhythmic classification
Beta-blocker cardioselectivity and ISA
Cephalosporin generations
Insulin types (onset/peak/duration)
ATD side effects
Anticancer drug classification by mechanism
Enzyme inducers/inhibitors
Drug receptor classification (α, β, muscarinic subtypes)

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