- Indications for Use:
- for active
TB, and the prevention of TB;
- Dosage:
- IM and IV routes rareley used;
- adult:
- 3-5mg/kg/24hr PO qd (up to 300mg/day) for 9 months as combination therapy;
- prophylaxis: 300mg/kg/24hr PO for 12 months;
- peds:
- active TB: 10-20 mg/kg/24hr PO (or IM) upto max dose of 300 mg/24hr for 9 months as combination therapy;
- prophylaxis: 10 mg/kg/24hr PO for 12 months;
- Cautions:
-
drug induced hepatitis;
- increased hepatotoxicity may occur w/ concomitant use of
rifampin, phenytoin, ETOH,
and is more common w/ previous infectious hepatitis;
- contraindicated with acute liver dz or w/ h/o INH associatted liver damage;
- in persons younger than 35 years of age, routine monitoring of adverse effects of Isoniazid
should consist of monthly symptom review;
- for persons 35 and older, in addition to monthly symptom reviews, hepatic enzymes should be
measured prior to starting
INH and periodically through out treatment;
-
peripheral neuropathy:
- may be caused be interference with metabolism of pyridoxine;
- alcoholics and diabetics are at higher risk;
- to prevent peripheral neuropathy can give pyridoxine 50-100mg/day;
- opthalomologic exam (before and during therapy) is recomended;
- may cause hallucinations:
- will increase levels of carbamazepine & phenytoin (look for incr Nystagmus, N, V, ataxia;
- will incr effects of benzodiazepines;
- INH will incr effects of oral anticoagulants;
- may cause hemolysis in pt w/ G6PD deficiency;
- Misc:
- note: Ratio of CSF to Blood Level (%): NormalMeninges / Inflammed Meninges:
20-90;
- Dosing Regimens for Patients with Renal Insufficiency: (Dose for 70kgAdult{gm/dosing interval inhours})
:CrCl:>80::0.3/24::50-79::0.3/24::CrCl:30-49::0.3/24::CrCl:10-29::0.3/24;;
