Important One-liners in Pharmacology

• In the same media, the drug becomes lipid-soluble
  • If a weak acidic drug is kept in more acidic pH media, it becomes highly non-ionic or lipid-soluble
  • If a weak basic drug is kept in more basic pH media, it becomes highly non-ionic or lipid-soluble
• In the opposite media, the drug becomes water-soluble
  • If a weak acidic drug is kept in more basic pH media, it becomes highly ionic or water-soluble
  • If a weak basic drug is kept in more acidic pH media, it becomes highly ionic or water-soluble
• Strong acidic or basic drugs are not influenced by the pH of the media
• Always remain ionic

• Basic drugs are absorbed from the small intestine (Duodenum) > stomach
• Acidic drugs are absorbed from the small intestine (Duodenum) > stomach
• All ACE inhibitors are prodrugs except Captopril and Lisinopril.
• Prodrugs are converted into active form by Phase 1 reaction.
• Most of the drugs are metabolized by the microsomal system.
• One gene hypothesis: One gene can make one type of enzyme. This hypothesis was rejected
• One gene can make one mRNA
• Different types and quantities of enzymes are produced
• More than 75 enzymes make CYP enzymes
• For enzyme inhibition, only one dose of the drug is required, but enzyme induction requires 7-14 days.
• When a free form of a drug gets excreted into the urine, the protein-bound drug, to maintain equilibrium, gets converted to free form. This free form gets excreted
• Amphetamine abusers mix it with sodium bicarbonate
  • Sodium bicarbonate makes urine more basic
  • Amphetamine (basic drug) in basic urine becomes lipid-soluble
  • More reabsorbed
  • Increased level in blood
  • More pleasure from amphetamine
• SSRIs do not require TDM, thus DOC for depression
• All anticancer drugs need TDM
• TDM is most commonly done in Cyclosporine and Tacrolimus
• Atropine-like drugs are contraindicated in Glaucoma
• The overall drug of choice for hypertension in pregnancy is labetalol.

Also read: Pharmacology Important Questions for NEET PG/FMGE 2025

Drugs Avoided in G6PD Deficiency

• Deficiency of antioxidant Glutathione (Protects RBC)
• Damage of RBC → hemolysis
• Drugs avoided (Mnemonic: MAD FANS)
  • Metronidazole
  • Aspirin
  • Dapsone
  • Fluoroquinolone
  • Antimalarials
  • Drugs containing Nitro groups
    • Antihypertensive: Nitroprusside
    • Antibiotic: Nitrofurantoin
  • Drugs containing Sulfa groups
    • Sulfonamide
    • Anti-TB: Isoniazid
  • Methylene blue (dye)
  • Fava beans (food products)
  • Chloramphenicol

Important MCQ-based questions

Q. Antacids mainly reduce the absorption of?

1. Acidic drugs
2. Basic drugs

Ans. Acidic drugs

• Antacids are basic drugs
• Neutralise HCl in stomach, neutralising the pH

Q. If a drug has a very high first-pass metabolism in the liver. Is this given orally or not?

Ans. Either they are not given orally or they are given in very high oral doses.

Also read: Introduction to Adrenergic drugs

Q. How to avoid (bypass) first-pass metabolism of the liver:

Ans. 

• By giving a drug by all other systemic routes except oral.
• Sublingual, rectal, and all parenteral routes

Q. If a drug has high Vd, there is no role of hemodialysis. Why?

Ans. High Vd drugs are not present in plasma. E.g., Digoxin (450L of plasma)

Q. If a drug has low Vd and high plasma protein binding, will hemodialysis be allowed?

Ans. No. Plasma protein will not allow the filtration of a drug. E.g. Warfarin (99% albumin-bound), Verapamil

Q. If a drug has low Vd and low plasma protein binding (free form), is hemodialysis allowed?

Ans. Yes

Q. The action of thiopentone is terminated by:

1. Redistribution into fats
2. Elimination into urine

Ans. Redistribution into fats

Also read: Rational Drug Prescribing and Essential Medicine

Q. Which skeletal muscle relaxant is safe in hepatic failure?

1. Atracurium
2. Succinylcholine

Ans. Atracurium

Q. Which drugs are excreted by sweat, saliva, and tears?

Ans. Lithium and metals like mercury

Q. Which antiepileptic drug gets excreted in the greatest amount in breast milk?

Ans. Levetiracetam

Q. Why does rifampin cause contraceptive failure?

Ans. Rifampicin increases the metabolism or degradation of estrogen by inducing CYP enzymes

Q. What is the drug that inhibits the OATP transporter?

Ans. Probenecid

Probenecid is combined with cephalosporins and penicillin because:

• Probenecid inhibits the excretion of penicillin and cephalosporins into the urine
• They remain in the blood for a longer duration
• Makes them longer acting by inhibiting the excretion

Also read: Pharmacogenetics: Gene Response to Medicine

Q. What drug is used to make urine acidic in the basic drug poisoning?

Ans. Ammonium chloride

Q. What is an antidote for amphetamine poisoning?

Ans. Ammonium chloride

Q. What is the general anesthetic Schedule X drug?

Ans. Ketamine

Q. Is the structure of methotrexate like folic acid? True or false?

Ans. True

Q. Can we overcome the effect of methotrexate by folic acid? True or false?

Ans. False

Q. Shortest acting mydriatic

Ans. Phenylephrine

• Pure mydriatic
• No action on ciliary muscles

Also read: Anti-Emetic Drugs

Q. Shortest-acting cycloplegic mydriatic

Ans. Tropicamide

Q. What is the net effect of norepinephrine on HR?

Ans. Bradycardia (because reflex predominates direct HR)

Q. Which drug causes bradycardia but is not directly acting on the heart?

Ans. Phenylephrine

Q. Which are combined a and b blockers?

Ans.

• Labetalol
• Bucindolol
• Carvedilol

Q. Which is the longest acting B blocker:

Ans. Nadolol

Q. Which is the least lipid-soluble B blocker?

Ans.

• Nadolol
• Atenolol
• Sotalol
• Acebutolol

Also read: Drugs Used for Cough

Q. Which is the most cardioselective soluble b blocker?

Ans. Nebivolol

Q. Which b blocker closes the potassium channel?

Ans. Sotalol

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