ISONIAZID Solution for injection Ref.[7980] Active ingredients: Isoniazid

Isoniazid 50 mg/2 ml Solution for Injection is for intramuscular, intravenous, intrapleural, or intrathecal injection.

Adults and children

The usual intramuscular or intravenous dose for adults is 200 to 300 mg as a single daily dose, for children 100 to 300 mg daily (10-20 mg/kg), but doses much larger than these are sometimes given, especially in conditions such as tuberculous meningitis. It is recommended to give an intravenous dose slowly as an undiluted bolus injection, although other methods may be employed.

Neonates

The recommended intravenous or intramuscular dose for neonates is 3-5 mg/kg with a maximum of 10 mg/kg daily. Isoniazid may be present in the milk of lactating mothers (see section 4.6).

The elderly

No dosage reduction is necessary in the elderly.

Intrapleural use

50 to 250 mg may be instilled intrapleurally after aspiration of pus, the dosage of oral isoniazid on that day being correspondingly reduced. The ampoule solution is also used for the local treatment of tuberculous ulcers, for irrigation of fistulae, etc.

Intrathecal use

It should be noted that CSF concentrations of isoniazid are approximately 90% of plasma concentrations. Where intrathecal use is required, 25-50 mg daily has been given to adults and 10-20 mg daily for children, according to age.

It is usual to give Isoniazid together with other antituberculous therapy, as determined by current practice and/or sensitivity testing.

It is recommended that pyridoxine be given during Isoniazid therapy to minimise adverse reactions, especially in malnourished patients and those predisposed to neuropathy (eg. diabetics and alcoholics) (see section 4.8).

Patients with renal impairment

No dosage reduction of Isoniazid is necessary when given to patients with mild renal failure. Patients with severe renal failure (glomerular filtration rate of less than 10 ml/minute) and slow acetylator status might require a dose reduction of about 100mg to maintain trough plasma levels at less than 1 mcg/ml.

Isonaizid is removed by both haemodialysis and peritoneal dialysis therefore isoniazid should be administered immediately after dialysis.

Patients with hepatic impairment

The possible risks of administration of Isoniazid to patients with pre-existing non-tuberculous hepatic disease should be balanced against the benefits expected from treating tuberculosis.

In severe poisoning the main risk is of epileptiform convulsions. Other features of CNS toxicity may be apparent including cerebellar syndrome. In addition any of the side-effects listed in section 4.8 may occur together with metabolic acidosis, hyperglycaemia, nausea, vomiting, tachycardia, dizziness, hyperreflexia, hallucinations, increased visual sensitivity, pyrexia and slurred speech.

The benefit of gastric decontamination is uncertain. Consider activated charcoal if the patient presents within 1 hour of ingestion of more than 20 mg/kg.

Consider gastric aspiration/lavage in adults within 1 hour of a potentially life-threatening overdose, providing the airway can be protected.

Treatment should be directed to the control of convulsions. Control convulsions initially with intravenous diazepam or lorazepam. Phenytoin is ineffective and not advised as isoniazid inhibits the metabolism of phenytoin. Large doses of pyridoxine may limit the occurrence of other adverse effects. Metabolic acidosis may require sodium bicarbonate infusion. The drug is removed by dialysis.

Shelf life: Three years.

Do not store above 25°C.

Protect from light.

Colourless glass ampoules coded with dark red and orange colour ring each containing 2 ml of solution, in packs of 10 ampoules.

None.