Questions and Answers
What is the therapeutic class of Isoniazid?
What is the pharmacologic class of Isoniazid?
What is the primary action of Isoniazid?
Inhibiting the synthesis of mycolic acids
What should be monitored due to the black box warning of Isoniazid?
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Isoniazid is contraindicated in patients with hypersensitivity to the drug.
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Isoniazid may be used alone for chemoprophylaxis, or in combination with other _____ drugs for treating active disease.
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When should Isoniazid be administered relative to meals?
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What is a common adverse effect of Isoniazid?
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What may increase the risk of hepatotoxicity when taking Isoniazid?
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What type of toxicity can Isoniazid potentially lead to?
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What should be done in the case of an Isoniazid overdose?
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Study Notes
Isoniazid Overview
- Antituberculosis drug classified as a mycolic acid inhibitor.
- First-line treatment for M. tuberculosis with proven safety and efficacy over 60 years.
Mechanism of Action
- Works by inhibiting mycolic acid synthesis, crucial for mycobacterial cell walls.
- Exhibits bactericidal effects against actively growing mycobacteria, while being bacteriostatic for dormant forms.
- Selectively targets M. tuberculosis.
Administration Guidelines
- Administer on an empty stomach; 1 hour after or 2 hours before meals.
- For intramuscular injections, ensure deep IM and rotate injection sites.
- Assigned to pregnancy category C.
Common Adverse Effects
- Frequently observed issues include numbness in extremities, rash, and fever.
- Potential neurotoxicity can lead to paresthesia, convulsions, optic neuritis, dizziness, coma, memory loss, and psychotic symptoms.
Black Box Warning
- Risk of hepatotoxicity, which can be severe or fatal; requires careful monitoring for jaundice, fatigue, elevated liver enzymes, and decreased appetite.
- Monthly liver enzyme testing recommended during therapy.
- Hepatotoxicity typically occurs within the first 1 to 3 months but can arise at any time.
- Older adults and those consuming alcohol daily face increased risk.
Contraindications
- Not to be used in individuals with hypersensitivity to isoniazid or severe hepatic impairment.
Drug Interactions
- Aluminum-containing antacids reduce isoniazid absorption; avoid concurrent use.
- Disulfiram may cause coordination issues and psychotic reactions when taken with isoniazid.
- Alcohol consumption raises hepatotoxicity risk.
- Increased serum levels of phenytoin and carbamazepine can occur with isoniazid.
- Food may hinder isoniazid absorption, particularly foods containing tyramine, which can heighten toxicity.
Overdose Management
- Isoniazid overdose can be fatal; treatment is primarily symptomatic.
- Administer pyridoxine (vitamin B6) equivalent to isoniazid overdose dosage to mitigate seizures and correct metabolic acidosis, with potential for repeated doses until the patient recovers consciousness.
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Description
This quiz provides an overview of Isoniazid, a key antituberculosis medication. It covers its mechanism of action, administration guidelines, common adverse effects, and important safety warnings. Test your knowledge on how this vital drug combats M. tuberculosis effectively.
