Category: Pharmacology

DAPSONE

Poojitha Surgi2 Comments

It is a sulphone, oldest and cheapest ; most widely used for leprosy

MECHANISM OF ACTION

ADVERSE EFFECTS

Dose related hemolytic anemia in G6PD deficiency,

OTHERS: Anorexia, Nausea, Vomiting, Fever, Headache, Allergic dermatitis, Itching, Peripheral neuropathy, Methaemoglobin

Exacerbation of lesions- ‘ sulphone syndrome‘:- fever, dermatitis, pruritis, lymphadenopathy, methaemoglobinaemia, anemia, hepatitis

PHARMACOKINETICS

🟡 Given orally

🟡 almost completely absorbed from gut

🟡 bound to plasma proteins

🟡 widely distributed in in body and concentrated in infected skin, muscle, liver, kidney

🟡 partly secreted in bile and undergoes enterohepatic cycling

🟡 metabolized by acetylation and metabolites are excreted in urine

Reference:

Pharmacology 4th Ed: Tara V Shanbhag, Smita Shenoy

ISONIAZIDE

Poojitha SurgiLeave a comment

Isonicotinic acid hydrazide (INH)

Highly effective and most widely used antitubercular agent.

MoA

Uses

First- line drug for treatment of TB. Used for chemo prophylaxis of TB.

Adv. E

  1. Hepatotoxicity : Common in alcoholics, elderly people, rapid acetylators. Symptoms like anorexia, nausea, vomiting, and jaundice are seen. Reversible on discontinuation of drug.
  2. PERIPHERAL NEURITIS : Competitively interferes with utilization of pyridoxine due to structural similarity. Peripheral neuritis is common in slow acetylators.

Pyridoxine 10mg/day + INH is given to reduce risk

3. Other side effects : Fever, skin rashes, arthralgia, anemia, GI disturbances, psychosis and rarely convulsions.

INH inhibits metabolism of pheytoin, carbamazepine, warfarin etc. ➡️ increases plasma levels of these drugs ➡️ may result in toxicity.

REFERENCE:

Pharmacology 4th Ed: Tara V Shanbhag, Smita Shenoy