CAUTIONS, FURTHER INFORMATION
▶Peripheral neuropathyPeripheral neuropathy is more likely
to occur where there are pre-existing risk factors such as
diabetes, alcohol dependence, chronic renal failure,
pregnancy, malnutrition and HIV infection. In patients at
increased risk of peripheral neuropathy, pyridoxine
hydrochloride p. 627 should be given prophylactically from
the start of treatment.
lINTERACTIONS→Appendix 1 : isoniazid
lSIDE-EFFECTS
▶UncommonHepatic disorders
▶Rare or very rareSevere cutaneous adverse reactions
(SCARs)
▶Frequency not knownAgranulocytosis.alopecia.anaemia.
aplastic anaemia.eosinophilia.fever.gynaecomastia.
haemolytic anaemia.hyperglycaemia.lupus-like
syndrome.nerve disorders.optic atrophy.pancreatitis.
pellagra.psychosis.seizure.skin reactions.
thrombocytopenia.vasculitis
lPREGNANCYNot known to be harmful; prophylactic
pyridoxine recommended.
lBREAST FEEDINGTheoretical risk of convulsions and
neuropathy; prophylactic pyridoxine advisable in mother.
MonitoringIn breast-feeding, monitor infant for possible
toxicity.
lHEPATIC IMPAIRMENTUse with caution.
MonitoringIn patients with pre-existing liver disease or
hepatic impairment monitor liver function regularly and
particularly frequently in thefirst 2 months.
lRENAL IMPAIRMENTRisk of ototoxicity and peripheral
neuropathy; prophylactic pyridoxine hydrochloride p. 627
recommended.
lMONITORING REQUIREMENTS
▶Renal functionshould be checked before treatment.
▶Hepatic functionshould be checked before treatment. If
there is no evidence of liver disease (and pre-treatment
liver function is normal), further checks are only necessary
if the patient develops fever, malaise, vomiting, jaundice
or unexplained deterioration during treatment.
lPRESCRIBING AND DISPENSING INFORMATIONDoses may
need to be recalculated to allow for weight gain in younger
children.
▶With oral useIn general, doses should be rounded up to
facilitate administration of suitable volumes of liquid or an
appropriate strength of tablet. The RCPCH and NPPG
recommend that, when a liquid special of isoniazid is
required, the following strength is used: 50 mg/ 5 mL.
lPATIENT AND CARER ADVICE
Hepatic disordersPatients or their carers should be told how
to recognise signs of liver disorder, and advised to
discontinue treatment and seek immediate medical
attention if symptoms such as persistent nausea,
vomiting, malaise or jaundice develop.
Medicines for Children leaflet: Isoniazid for latent
tuberculosiswww.medicinesforchildren.org.uk/isoniazid-for-
latent-tuberculosis
Medicines for Children leaflet: Isoniazid for treatment of
tuberculosiswww.medicinesforchildren.org.ukisoniazid-for-the-
treatment-of-tuberculosislMEDICINAL FORMS
There can be variation in the licensing of different medicines
containing the same drug. Forms available from special-order
manufacturers include: oral suspension, oral solution
Solution for injection
▶Isoniazid (Non-proprietary)
Isoniazid 25 mg per 1 mlIsoniazid 50 mg/ 2 ml solution for injection
ampoules| 10 ampouleP£ 361. 98Tablet
CAUTIONARY AND ADVISORY LABELS8, 22
▶Isoniazid (Non-proprietary)
Isoniazid 50 mgIsoniazid 50 mg tablets| 56 tabletP£ 19. 28 DT
=£ 19. 26
Isoniazid 100 mgIsoniazid 100 mg tablets| 28 tabletP£ 19. 24
DT = £ 19. 24
Isoniazid 300 mgIsoniazid 300 mg tablets| 30 tabletPs
Combinations available:Rifampicin with isoniazid,p. 366.
Rifampicin with isoniazid and pyrazinamide,p. 366Pyrazinamide
lINDICATIONS AND DOSE
Tuberculosis, in combination with other drugs (standard
unsupervised 6 -month treatment)
▶BY MOUTH
▶Child (body-weight up to 50 kg): 35 mg/kg once daily for
2 months (initial phase); maximum 1. 5 g per day
▶Child (body-weight 50 kg and above): 35 mg/kg once daily
for 2 months (initial phase); maximum 2 g per day
Tuberculosis, in combination with other drugs
(intermittent supervised 6 -month treatment) (under
expert supervision)
▶BY MOUTH
▶Child (body-weight up to 50 kg): 50 mg/kg 3 times a week
(max. per dose 2 g 3 times a week) for 2 months (initial
phase)
▶Child (body-weight 50 kg and above): 50 mg/kg 3 times a
week (max. per dose 2. 5 g 3 times a week) for 2 months
(initial phase)
Congenital tuberculosis, in combination with other drugs
▶BY MOUTH
▶Neonate: 35 mg/kg once daily for 2 months (initial
phase).lCAUTIONSDiabetes
lINTERACTIONS→Appendix 1 : pyrazinamide
lSIDE-EFFECTSAppetite decreased.arthralgia.dysuria.
flushing.gout aggravated.hepatic disorders.malaise.
nausea.peptic ulcer aggravated.photosensitivity reaction
.sideroblastic anaemia.skin reactions.splenomegaly.
vomiting
lPREGNANCYManufacturer advises use only if potential
benefit outweighs risk.
lBREAST FEEDINGAmount too small to be harmful.
lHEPATIC IMPAIRMENTIdiosyncratic hepatotoxicity more
common; avoid in severe hepatic impairment.
MonitoringIn patients with pre-existing liver disease or
hepatic impairment monitor liver function regularly and
particularly frequently in thefirst 2 months.
lRENAL IMPAIRMENT
Dose adjustmentsIf estimated glomerularfiltration rate
less than 30 mL/minute/ 1. 73 m^2 ,use 25 – 30 mg/kg 3 times
a week.
lMONITORING REQUIREMENTS
▶Renal functionshould be checked before treatment.
▶Hepatic functionshould be checked before treatment. If
there is no evidence of liver disease (and pre-treatment
liver function is normal), further checks are only necessary
if the patient develops fever, malaise, vomiting, jaundice
or unexplained deterioration during treatment.
lPRESCRIBING AND DISPENSING INFORMATIONIn general,
doses should be rounded up to facilitate administration of
suitable volumes of liquid or an appropriate strength of
tablet. Doses may also need to be recalculated to allow for
weight gain in younger children.368 Bacterial infection BNFC 2018 – 2019
Infection5