Spectrum: Local Antimicrobial Stewardship, for UCLA Health

Isoniazid

C. diff Risk

Low

Oral Bioavailability

Moderate

Approximate Cost

$

Spectrum Of Activity

General Spectrum of Activity

Spectrum Of Activity

Dosing

Adult

Once-Daily Therapy
5 mg/kg/dose (usual dose: 300 mg) once daily

Altnerate options available, including 3 times weekly therapy.

Please consult ID

Renal - Adult

CrCl <50 mL/min or Dialysis

  • No change

CrCl >50 mL/min

  • 300 mg PO Q24h

Hepatic - Adult

There are no dosage adjustments; however, use with caution, may accumulate and additional liver damage may occur in patients with preexisting liver disease.

Contraindicated in patients with acute liver disease or previous isoniazid-associated hepatic injury.

Treatment with isoniazid for latent tuberculosis infection should be deferred in patients with acute hepatic diseases.

General Information

Common Usage

Common Usage

  • Active Tuberculosis

  •  Latent Tuberculosis

  •  Nontuberculous mycobacterium (M. kansasii)

Drug Monitoring

Drug Monitoring

Laboratory

  •  LFTs in patients with underlying liver disease or comorbidities

  • For ALT or AST >3 times the ULN: discontinue or temporarily withhold treatment.

Clinical

  • Monitor for signs of hepatic dysfunction

Adverse Effects

Adverse Effects

>10%: Hepatic: Increased serum transaminases (mild and transient 10% to 20%)

Major Interactions

Major Interactions

Multiple CYP Interactions