Straight A Nursing Podcast: Isoniazid Overview

Introduction

• Host: Nursing Mo
• Topic: Isoniazid, a medication commonly used in the treatment of tuberculosis (TB)
• Abbreviation: INH
• Brand Name: Isotamine (rarely used)
• Episode Reference: 218 for more info on tuberculosis
• Framework Used: Straight A Nursing Drugs Framework

Drug Classification

• Therapeutic Class: Anti-tubercular
• Pharmacologic Class: Mycolic acid inhibitor
• Mechanism: Inhibits the synthesis of mycolic acid, disrupting cell walls and DNA synthesis in mycobacteria

Pharmacokinetics

• Peak Concentration: 1-2 hours after dosing
• Absorption Issues: Delayed by food and antacids; should be taken on an empty stomach
• Crosses Blood-Brain Barrier: Yes, CSF levels = serum levels
• Placenta and Breast Milk: Yes, but safety not established in pregnant/lactating women

Administration Routes

• Oral: Tablet or liquid (flavors: orange, raspberry)
• Intramuscular (IM): Rotate injection sites, possible discomfort
• Important Note: Not FDA-approved for IV but may see it ordered as IV; confirm with a prescriber or pharmacist

Dosage Guidelines

• Daily: Maximum 300 mg
• 2-3 times per week: Maximum 900 mg

Usage

• Conditions Treated: Latent and active tuberculosis (often in combination with other drugs)
• First-Line Treatment: Tuberculosis meningitis
• Contraindications: Pancreatitis, acute liver disease, history of hepatitis from INH
• Caution: Liver disease, chronic alcohol use, severe kidney disease, pregnant/breastfeeding women, patients with diabetes or malnourishment
• Higher Risk: Black and Hispanic women for hepatotoxicity

Guidelines for Administration

• Medication Adherence: Critical to prevent drug-resistant strains; directly observed therapy (DOT) recommended
• Taking the Medication: On an empty stomach (1 hour before or 2 hours after meals); stagger use with aluminum-containing antacids
• Dietary Considerations: Avoid tyramine-containing foods (e.g., aged cheeses, fermented foods, cured meats, caffeine, beer)

Monitoring and Assessment

• Drug Resistance: Assessed before and during therapy
• Liver Function: Regular monitoring (AST, ALT, serum bilirubin)
• Symptoms to Watch: Abdominal pain, nausea, vomiting, jaundice, bruising, facial edema
• Neurological Effects: Monitor for altered mental status, seizures, peripheral neuropathy
• Other Signs: Fever, unusual bleeding, infection symptoms (sore throat, fatigue)
• Lab Tests: Platelets, creatinine, sputum cultures (until two negative results)
• Pregnancy: Category C; potential benefits vs risks; may require pyridoxine (vitamin B6) to prevent toxicity
• Renal Disease: Dose adjustments and timing around dialysis required

Drug Interactions

• Phenytoin: Increased blood levels
• Theophylline: Reduced elimination, risk of toxicity
• Antacids (Aluminum): Decreased absorption
• Carbamazepine: Increased risk of hepatotoxicity
• Warfarin: Increased risk of bleeding
• Disulfiram: Risk of psychosis and ataxia
• General Hepatotoxic Drugs: Increased liver toxicity risk

Patient Teaching

• Medication Adherence: Long-term adherence is critical; DOT is standard
• Side Effects and Toxicity: Nausea, vomiting, rash, ataxia, altered mental status, slurred speech, dizziness, fever
• Avoid Alcohol: To reduce hepatotoxicity risk
• Diet: Avoid tyramine-containing foods
• Treatment Duration: Continue until advised by a healthcare provider
• Prevent Spread: General TB precautions

Side Effects

• Neurological: Peripheral neuropathy (most common), ataxia, seizure, psychosis
• GI: Hepatic impairment, nausea, vomiting, pancreatitis
• Dermatologic: Rash, severe conditions like Stevens-Johnson syndrome
• General: Fever, visual disturbances, anemia, drug-induced lupus erythematosus
• Isoniazid Toxicity: More common in B6/GABA deficiency; symptoms include nausea, vomiting, ataxia, mental status changes, seizures

Conclusion

• Upcoming Episode: Neurological assessment fundamentals
• Contact: Straight A Nursing Podcast