Isoniazid
Also known as: Isonicotic Acid Hydrazide, INH, Isonicotinyl Hydrazine
Isoniazid is the hydrazide of isonicotinic acid.Isoniazid is structurally similar to pyridoxine and introduced in 1952. It is the most active drug for the treatement of tuberculosis caused by susceptible strains used either alone or in combination with other drugs. It is prepared by chemical synthesis. It is available in combination with pyrazinamide, rifampicin, ethambutol, pyridoxine and cyanocobalamine.
Primary Characteristics
Isoniazid is also known as Isonicotic Acid Hydrazide, INH, Isonicotinyl Hydrazine.
It is of Synthetic origin and belongs to Hydrazine.
It belongs to Antimycobacterial agent pharmacological group on the basis of mechanism of action. It is also classified under Antituberculous Drugs .
Molecular Weight: 137.1 · pKa: 1.8, 3.5, 9.5 · Solubility in Water: 1 in 8 · Solubility in Alcohol: 1 in 50 · Non-proprietary name: Isoniazid.
Pharmacokinetics
Absorption: Isoniazid has an oral bioavailability is 95.5% (±4.5%).
Distribution: Isoniazid has a volume of distribution is 0.6-0.8 l/kg. plasma protein binding is negligible.
Elimination: it is metabolised via Hepatic & Intestinal, plasma half-life is 1-6 hr, renal excretion is 95%.
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Indications
Isoniazid is primarily indicated in conditions like Acute leukemia, Mycobacterial infection, Prophylaxis of TB, Tuberculosis, Vestibular disorders.
Isoniazid is also indicated for secondary conditions like Pulmonary TB.
Contraindications
Isoniazid is contraindicated in conditions like Diabetes mellitus, Seizures, Hypersensitivity.
Dosage
Isoniazid's dosage details are as follows:
| Dose | Single Dose | Frequency | Route | Instructions |
|---|---|---|---|---|
| Adult Dosage | ||||
| 5 mg /kg | 5 mg /kg | Every 24h | PO | Give 30 min. before breakfast for 2 months. To maximum of 300mg |
| Paediatric Dosage (20kg) | ||||
| 15 mg/kg | 15 mg/kg | Every 24h | Intra Muscular | Single Dose |
| 10 mg/kg | 10 mg/kg | Every 24h | Intra Venous | Single Dose |
| 10 mg/kg | 10 mg/kg | Every 24h | Oral | Single Dose |
| Neonatal Dosage (3kg) | ||||
| 12.5 mg/kg | 12.5 mg/kg | Every 24h | Intavenous | |
| 12.5 mg/kg | 12.5 mg/kg | Every 24h | Intramuscular | |
| 12.5 mg/kg | 12.5 mg/kg | Every 24h | Oral | |
Drug Interactions
Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.
Side Effects
Isoniazid in overdosage may give rise to further complications which include Hepatotoxicity , Pancreatitis , Lupus erythematosus , Peripheral neuropathy , Hepatotoxicity , Gynecomastia, Increase liver enzyme.
Isoniazid produces potentially life-threatening effects which include Hepatitis . Careful monitoring is needed with proper medical management.
The signs and symptoms that are produced after acute overdosage of Isoniazid are Nausea, Vomiting, Tachycardia , Convulsions , Coma, Seizures, Tachycardia, Urinary retention, Hallucinations , Metabolic acidosis, Hyperglycemia, Dizziness, Respiratory distress, Hyperreflexia , Slurred speech, hyperreflexia.
Isoniazid is known to cause more or less tolerable side effects which are usually transient. These include Diarrhea, Fever, Nausea, Skin eruptions, Skin rashes, Vasculitis, Vomiting .
Warnings / Precautions
Interference in Pathology
Isoniazid may interfere in the diagnosis of False positive result of urine in diabetics using clinitest..
Available Brands
Storage Conditions
Drug Classification
- 1.6.2.4 — Anti-tuberculosis drugs