Dosage and Frequency
- Adults: Typically, 300 mg orally once daily or 15 mg/kg (up to 900 mg) orally once daily.
- Children: Dosage based on weight, typically 10-15 mg/kg (up to 300 mg) orally once daily.
Route of Administration (ROA)
Oral administration.
Mechanism of Action (MOA)
Isoniazid inhibits the synthesis of mycolic acids, a key component of the mycobacterial cell wall, disrupting cell wall integrity and leading to bacterial cell death.
Pharmacokinetics (PK)
- Absorption: Rapidly and well absorbed after oral administration.
- Distribution: Widely distributed in body tissues.
- Metabolism: Metabolized in the liver by acetylation.
- Excretion: Primarily excreted via urine as metabolites.
Pathophysiology
Isoniazid targets and kills actively replicating tubercle bacilli, reducing the bacterial load and preventing the spread of tuberculosis (TB) infection. It inhibits the synthesis of mycolic acids, essential components of the bacterial cell wall.
Indications
- Treatment of active tuberculosis (TB) infection.
- Prophylaxis in individuals exposed to TB who are at high risk of developing active disease.
Contraindications
- Hypersensitivity to isoniazid or any component of the formulation.
- Severe liver disease or active liver injury.
- Acute porphyria.
Drug Interactions
- Rifampin: May decrease serum concentrations of isoniazid.
- Phenytoin: Isoniazid may increase serum concentrations of phenytoin.
- Alcohol: Concurrent use of alcohol may increase the risk of hepatotoxicity.
Precautions
- Monitor liver function tests regularly during treatment.
- Caution in patients with a history of liver disease, alcoholism, or other factors predisposing to hepatotoxicity.
- Avoid use in patients with peripheral neuropathy, optic neuritis, or other neurological conditions unless benefits outweigh risks.
This information provides a comprehensive overview of isoniazid, including dosage, administration, mechanism of action, pharmacokinetics, pathophysiology, indications, contraindications, drug interactions, and precautions. It is essential to follow healthcare provider recommendations and guidelines for the safe and effective use of isoniazid.
Medication Information and Guidelines
| Question | Answer |
|---|---|
| What’s the purpose of taking this medication? | Isoniazid is primarily used for the treatment of active tuberculosis (TB) infection and prophylaxis in individuals exposed to TB who are at high risk of developing active disease. |
| How is one supposed to use this medicine? | Dosage: Typically, 300 mg orally once daily for adults or 10-15 mg/kg (up to 300 mg) orally once daily for children. <br> Route of Administration: Oral. |
| Are there other reasons people might use this medication? | Isoniazid may be used off-label for the treatment of latent TB infection or as part of combination therapy for non-tuberculous mycobacterial infections. |
| Are there any specific things one need to be careful about while taking this medication? | – Monitor liver function tests regularly during treatment. <br> – Use with caution in patients with a history of liver disease, alcoholism, or other factors predisposing to hepatotoxicity. <br> – Avoid use in patients with peripheral neuropathy, optic neuritis, or other neurological conditions unless benefits outweigh risks. |
| Do one need to make any changes to diet while they are on this medication? | No specific dietary restrictions, but it is advisable to avoid consuming alcohol during treatment as it may increase the risk of hepatotoxicity. |
| What should one do if he/she forget to take a dose? | If a dose is missed, take it as soon as remembered. If it’s almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not double the dose to catch up. |
| What are the possible side effects of this medication? | Common side effects include nausea, vomiting, abdominal pain, headache, and rash. Serious side effects include hepatotoxicity, peripheral neuropathy, and optic neuritis. |
| How should one store and dispose of this medication properly? | Store at room temperature away from moisture and heat. Keep the medication in its original container, tightly closed, and out of reach of children. Dispose of any unused or expired medication according to local regulations or guidelines. |
| What should one do if something goes wrong, as in an overdose or emergency situation? | Seek immediate medical attention or contact a poison control center in case of an overdose. Symptoms may include nausea, vomiting, dizziness, seizures, and coma. |
| Monitoring and Laboratory Tests | Regular monitoring of liver function tests is recommended during treatment with isoniazid to detect any signs of hepatotoxicity. Additionally, periodic assessment of peripheral neuropathy symptoms and optic function may be warranted in some patients. |