Isoniazid
(Redirected from Ido-tebin)
Isoniazid (often abbreviated as INH) is an antibiotic primarily used for the treatment and prevention of tuberculosis (TB). Since its discovery in the early 1950s, it has become a cornerstone drug in first-line anti-tuberculosis regimens worldwide. Its mechanism of action involves inhibiting the synthesis of mycolic acids, which are essential components of the bacterial cell wall of Mycobacterium tuberculosis.
Overview[edit | edit source]
Isoniazid is an essential medicine on the World Health Organization's List of Essential Medicines, emphasizing its significance in global health. It is often prescribed in combination with other anti-tuberculosis drugs to enhance efficacy and prevent the emergence of drug-resistant TB strains.
Pharmacology[edit | edit source]
- Mechanism of Action: Isoniazid is a prodrug and, once activated by the bacterial catalase enzyme KatG, inhibits the synthesis of mycolic acids in Mycobacterium tuberculosis. This leads to impaired cell wall synthesis and bacterial cell death.
- Metabolism: It is primarily metabolized in the liver via acetylation. Genetic factors determine the rate of acetylation, with individuals being classified as slow or fast acetylators.
- Excretion: The drug is primarily excreted in urine.
Indications[edit | edit source]
- Treatment of active tuberculosis, often in combination with other drugs like rifampicin, pyrazinamide, and ethambutol.
- Prophylactic treatment in individuals who have been exposed to active TB cases, especially in close contacts.
- Latent TB infections.
Contraindications[edit | edit source]
Isoniazid is contraindicated in individuals:
- With acute liver disease or a history of drug-induced hepatitis.
- With severe hypersensitivity reactions to the drug.
Side Effects[edit | edit source]
Like all drugs, isoniazid is associated with a range of side effects:
- Hepatotoxicity: It can cause drug-induced liver injury, ranging from asymptomatic increases in liver enzymes to acute liver failure.
- Peripheral neuropathy: This may manifest as tingling or numbness in the extremities.
- Gastrointestinal symptoms: Including nausea, vomiting, and abdominal discomfort.
- Rash.
- Fever.
- Hematological disorders: Such as anemia, thrombocytopenia, or leukopenia.
- CNS effects: Including seizures, psychosis, or dizziness.
Drug Interactions[edit | edit source]
- Isoniazid may increase blood levels of phenytoin, leading to phenytoin toxicity.
- Concurrent use with alcohol increases the risk of hepatotoxicity.
- Antacids can reduce the absorption of isoniazid if taken simultaneously.
Prophylaxis and Management[edit | edit source]
To reduce the risk of peripheral neuropathy, pyridoxine (vitamin B6) supplementation is recommended, especially in pregnant women, breastfeeding mothers, malnourished individuals, and those with diabetes or HIV.
Resistance[edit | edit source]
Resistance to isoniazid is a growing concern, especially in regions with high TB burden. It is usually due to mutations in the katG gene or inhA promoter of the bacterium.
See Also[edit | edit source]
Isoniazid Resources | ||
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