Description

Simple

An antibiotic used to treat tuberculosis.

Clinical

An antibiotic used to treat mycobacterial infections; most commonly use in combination with other antimycobacterial agents for the treatment of active or latent tuberculosis.

Overview

Antibacterial agent used primarily as a tuberculostatic. It remains the treatment of choice for tuberculosis.

Pharmacology

Indication

For the treatment of all forms of tuberculosis in which organisms are susceptible.

Pharmacodynamic

Isoniazid is a bactericidal agent active against organisms of the genus Mycobacterium, specifically M. tuberculosis, M. bovis and M. kansasii. It is a highly specific agent, ineffective against other microorganisms. Isoniazid is bactericidal when mycobacteria grow rapidly and ba... Read more

Mechanism of action

Isoniazid is a prodrug and must be activated by bacterial catalase. Specficially, activation is associated with reduction of the mycobacterial ferric KatG catalase-peroxidase by hydrazine and reaction with oxygen to form an oxyferrous enzyme complex. Once activated, isoniazid inhibits the synthesis... Read more

Absorption

Readily absorbed following oral administration; however, may undergo significant first pass metabolism. Absorption and bioavailability are reduced when isoniazid is administered with food.

Protein binding

Very low (0-10%)

Volume of distribution

Information currently not available.

Clearance

Information currently not available.

Half life

Fast acetylators: 0.5 to 1.6 hours. Slow acetylators: 2 to 5 hours.

Route of elimination

From 50 to 70 percent of a dose of isoniazid is excreted in the urine within 24 hours.

Toxicity

LD50 100 mg/kg (Human, oral). Adverse reactions include rash, abnormal liver function tests, hepatitis, peripheral neuropathy, mild central nervous system (CNS) effects. In vivo, Isoniazid reacts with pyridoxal to form a hydrazone, and thus inhibits generation of pyridoxal phosphate. Ison... Read more

Adverse Effects

Contraindications

  • Regions: US
  • Patient Conditions:
      • Name: Severe adverse drug reaction
      • Drugbank Id: DBCOND0108069
      • Modification Of:
        • Base:
          • Name: Adverse Drug Reaction
          • Drugbank Id: DBCOND0055066
        • Severity:
          • Includes:
            • severe

Food Interactions

  • Administer vitamin supplements.
  • Avoid aged foods (cheese, red wine).
  • Avoid alcohol. Avoid alcohol, especially beer, unless approved by your physician.
  • Avoid chocolate.
  • Avoid cured food (bacon, processed meat).
  • Avoid fava beans.
  • Avoid histamine. Histamine-containing foods (e.g., skipjack, tuna, other tropical fish) can cause headaches, sweating, palpitations, flushing, and hypotension.
  • Avoid pickled foods.
  • Avoid tyramine. Tyramine-containing foods include cheese and red wine.
  • Take at least 2 hours before or after antacids. Taking this medication with antacids can reduce absorption.
  • Take at least 2 hours before or after calcium supplements. Taking this medication with calcium supplements can reduce its absorption.
  • Take at least 2 hours before or after iron supplements. Taking this medication with iron supplements can reduce its absorption.
  • Take on an empty stomach. Take at least 1 hour before or 2 hours after meals.
  • Take with a full glass of water.

Interactions

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  • Paracetamol(acetaminophen)
  • Paxil(paroxetine)
  • Pamelor(nortriptyline)
  • Panadol(acetaminophen)
  • Patanol(olopatadine ophthalmic)
  • Pataday(olopatadine ophthalmic)
  • Parnate(tranylcypromine)
  • Pazeo(olopatadine ophthalmic)
(R)-warfarin
The serum concentration of (R)-warfarin can be increased when it is combined with Isoniazid.
(S)-Warfarin
The serum concentration of (S)-Warfarin can be increased when it is combined with Isoniazid.
2,5-Dimethoxy-4-ethylamphetamine
The risk or severity of serotonin syndrome can be increased when Isoniazid is combined with 2,5-Dimethoxy-4-ethylamphetamine.
2,5-Dimethoxy-4-ethylthioamphetamine
The risk or severity of serotonin syndrome can be increased when Isoniazid is combined with 2,5-Dimethoxy-4-ethylthioamphetamine.
25-desacetylrifapentine
25-desacetylrifapentine may increase the hepatotoxic activities of Isoniazid.
3-isobutyl-1-methyl-7H-xanthine
The serum concentration of 3-isobutyl-1-methyl-7H-xanthine can be increased when it is combined with Isoniazid.
4-Bromo-2,5-dimethoxyamphetamine
The risk or severity of serotonin syndrome can be increased when Isoniazid is combined with 4-Bromo-2,5-dimethoxyamphetamine.
4-hydroxycoumarin
The metabolism of 4-hydroxycoumarin can be decreased when combined with Isoniazid.
5-methoxy-N,N-dimethyltryptamine
The risk or severity of serotonin syndrome can be increased when Isoniazid is combined with 5-methoxy-N,N-dimethyltryptamine.
6-O-benzylguanine
The serum concentration of 6-O-benzylguanine can be increased when it is combined with Isoniazid.
7-Deazaguanine
The serum concentration of 7-Deazaguanine can be increased when it is combined with Isoniazid.
7-Nitroindazole
The therapeutic efficacy of 7-Nitroindazole can be decreased when used in combination with Isoniazid.
7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline
The risk or severity of serotonin syndrome can be increased when Isoniazid is combined with 7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline.
7,9-Dimethylguanine
The serum concentration of 7,9-Dimethylguanine can be increased when it is combined with Isoniazid.
8-azaguanine
The serum concentration of 8-azaguanine can be increased when it is combined with Isoniazid.
8-chlorotheophylline
The serum concentration of 8-chlorotheophylline can be increased when it is combined with Isoniazid.
9-aminocamptothecin
The metabolism of 9-aminocamptothecin can be decreased when combined with Isoniazid.
9-Deazaguanine
The serum concentration of 9-Deazaguanine can be increased when it is combined with Isoniazid.
9-Methylguanine
The serum concentration of 9-Methylguanine can be increased when it is combined with Isoniazid.
Abacavir
Isoniazid may decrease the excretion rate of Abacavir which could result in a higher serum level.