Niazid
Generic Name
Isoniazid
Manufacturer
Square Pharmaceuticals Ltd.
Country
Bangladesh
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Price Details
Current market pricing information
| Variant | Unit Price | Strip Price |
|---|---|---|
| niazid 500 mg tablet | ৳ 10.00 | ৳ 40.00 |
Description
Overview of the medicine
Niazid 500 mg Tablet contains Isoniazid, an anti-tubercular agent used for the treatment and prevention of tuberculosis (TB). It is often used in combination with other anti-TB drugs.
Uses & Indications
Dosage
Adults
For active TB: 5 mg/kg once daily or 15 mg/kg 2-3 times per week (Max 900 mg), always in combination. For LTBI: 300 mg once daily for 6-9 months or 900 mg twice weekly for 6-9 months (often with pyridoxine). A 500mg dose is less common for daily active TB treatment but may be used in specific regimens or for LTBI.
Elderly
Similar to adult dosage, but close monitoring for adverse effects, especially hepatotoxicity and neuropathy, is recommended.
Renal_impairment
Dosage adjustment may be necessary in severe renal impairment (creatinine clearance < 10 mL/min). Administer 250-300 mg once daily or 2-3 times per week.
How to Take
Take orally, usually on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption. May be taken with food if gastrointestinal upset occurs. Administer pyridoxine (Vitamin B6) concomitantly to prevent neuropathy, especially in high-risk patients.
Mechanism of Action
Isoniazid is a prodrug that, once activated by the mycobacterial catalase-peroxidase enzyme (KatG), inhibits the synthesis of mycolic acids, which are essential components of the mycobacterial cell wall. This leads to disruption of the cell wall and bacterial death.
Pharmacokinetics
Onset
Peak plasma concentrations reached within 1-2 hours.
Excretion
Mainly excreted in urine (75-95%) within 24 hours, primarily as metabolites. A small amount is excreted in feces.
Half life
Plasma half-life is 1-4 hours, depending on acetylator status (fast vs. slow acetylators).
Absorption
Rapidly and completely absorbed from the gastrointestinal tract; food may decrease the rate and extent of absorption.
Metabolism
Primarily metabolized in the liver by N-acetylation to acetylisoniazid, which is then hydrolyzed to isonicotinic acid and acetylhydrazine. Acetylhydrazine is further metabolized and can be hepatotoxic.
Side Effects
Contraindications
- Previous isoniazid-associated liver injury
- Acute liver disease
- Hypersensitivity to isoniazid or any component of the formulation
Drug Interactions
Alcohol
Increases the risk of hepatotoxicity and peripheral neuropathy.
Rifampicin
Increases the risk of hepatotoxicity when co-administered with isoniazid.
Cycloserine
May increase CNS adverse effects (e.g., dizziness, drowsiness).
Acetaminophen
Concurrent use may increase the risk of hepatotoxicity.
Antacids (aluminum-containing)
May reduce the absorption of isoniazid. Administer isoniazid at least 1 hour before antacids.
Carbamazepine, Phenytoin, Valproic acid
Isoniazid can increase plasma levels of these drugs, leading to toxicity. Dose adjustment and monitoring are required.
Storage
Store in a cool, dry place, below 30°C. Protect from light and moisture. Keep out of reach of children.
Overdose
Symptoms of overdose include nausea, vomiting, dizziness, blurred vision, slurred speech, hallucinations, and CNS depression leading to coma. Severe metabolic acidosis and seizures are common. Management involves supportive care, gastric lavage, activated charcoal, and intravenous administration of pyridoxine (Vitamin B6) at doses equivalent to or higher than the amount of isoniazid ingested to counteract CNS toxicity.
Pregnancy & Lactation
Pregnancy Category C. Isoniazid crosses the placenta. Benefits of treating TB in pregnant women generally outweigh risks. Pyridoxine supplementation is recommended. Isoniazid is excreted in breast milk. Breastfeeding is generally considered compatible, but infants should be monitored for potential adverse effects. Consult a doctor.
Side Effects
Contraindications
- Previous isoniazid-associated liver injury
- Acute liver disease
- Hypersensitivity to isoniazid or any component of the formulation
Drug Interactions
Alcohol
Increases the risk of hepatotoxicity and peripheral neuropathy.
Rifampicin
Increases the risk of hepatotoxicity when co-administered with isoniazid.
Cycloserine
May increase CNS adverse effects (e.g., dizziness, drowsiness).
Acetaminophen
Concurrent use may increase the risk of hepatotoxicity.
Antacids (aluminum-containing)
May reduce the absorption of isoniazid. Administer isoniazid at least 1 hour before antacids.
Carbamazepine, Phenytoin, Valproic acid
Isoniazid can increase plasma levels of these drugs, leading to toxicity. Dose adjustment and monitoring are required.
Storage
Store in a cool, dry place, below 30°C. Protect from light and moisture. Keep out of reach of children.
Overdose
Symptoms of overdose include nausea, vomiting, dizziness, blurred vision, slurred speech, hallucinations, and CNS depression leading to coma. Severe metabolic acidosis and seizures are common. Management involves supportive care, gastric lavage, activated charcoal, and intravenous administration of pyridoxine (Vitamin B6) at doses equivalent to or higher than the amount of isoniazid ingested to counteract CNS toxicity.
Pregnancy & Lactation
Pregnancy Category C. Isoniazid crosses the placenta. Benefits of treating TB in pregnant women generally outweigh risks. Pyridoxine supplementation is recommended. Isoniazid is excreted in breast milk. Breastfeeding is generally considered compatible, but infants should be monitored for potential adverse effects. Consult a doctor.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
2-3 years from manufacturing date
Availability
Pharmacies, Hospitals
Approval Status
Approved (globally and locally)
Patent Status
Generic
WHO Essential Medicine
YesClinical Trials
Isoniazid has been extensively studied in numerous clinical trials since its introduction for the treatment and prevention of tuberculosis. Ongoing research focuses on optimizing regimens and addressing drug resistance.
Lab Monitoring
- Liver function tests (LFTs) at baseline and periodically (e.g., monthly) during therapy, especially in high-risk patients (elderly, chronic alcohol users).
- Renal function tests if renal impairment is suspected or severe.
- Complete blood count (CBC) occasionally, if hematological abnormalities are suspected.
Doctor Notes
- Crucially monitor LFTs at baseline and monthly. Educate patients on symptoms of hepatitis and neuropathy.
- Always prescribe pyridoxine (10-25 mg/day) concurrently to all patients on isoniazid, especially those at higher risk of neuropathy (e.g., diabetics, alcoholics, malnourished, elderly, HIV-positive, pregnant/breastfeeding).
- Emphasize strict adherence to the regimen to prevent drug resistance and ensure treatment efficacy.
- Advise patients to avoid alcohol and certain foods during therapy.
Patient Guidelines
- Take the medicine exactly as prescribed by your doctor; do not miss doses.
- Complete the full course of treatment, even if you feel better, to prevent drug resistance.
- Report any symptoms of liver problems (e.g., unusual tiredness, dark urine, yellowing of skin/eyes) or nerve problems (e.g., tingling, numbness in hands/feet) to your doctor immediately.
- Take pyridoxine (Vitamin B6) as advised by your doctor to reduce the risk of neuropathy.
Missed Dose Advice
If a dose is missed, take it as soon as you remember, unless it is almost time for your next dose. In that case, skip the missed dose and continue with your regular dosing schedule. Do not double dose to make up for a missed one.
Driving Precautions
Isoniazid can cause dizziness, lightheadedness, or blurred vision in some individuals. Exercise caution when driving or operating machinery until you know how the medicine affects you.
Lifestyle Advice
- Avoid or minimize alcohol consumption during treatment due to increased risk of liver damage.
- Discuss your diet with your doctor regarding tyramine and histamine-rich foods.
- Maintain good nutrition and hydration.
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