Carbamazepine (Paediatric)

SOURCE: eMC UK SPC, productName 'Carbamazepine 100 mg/5 ml Oral Suspension', §4.2. FORMULATION CAVEAT: 'Since a given dose of carbamazepine oral suspension will produce higher peak levels than the same dose in tablet form, it is advisable to start with low doses of the liquid and to increase them slowly so as to avoid adverse effects on the central nervous system such as dizziness and lethargy. When switching a patient from tablets to liquid the same overall dose may be used but in smaller, more frequent, doses.' PLASMA LEVELS: 'In the treatment of epilepsy, the dose of carbamazepine usually requires total plasma-carbamazepine concentrations of about 4 to 12 micrograms/mL (17 to 50 micromoles/litre).' HLA-B*1502: before deciding to initiate treatment, patients of Han Chinese and Thai origin should whenever possible be screened for HLA-B*1502, as this allele strongly predicts the risk of severe carbamazepine-associated Stevens-Johnson syndrome. TRIGEMINAL NEURALGIA: slowly raise the initial dosage of 200–400 mg daily until freedom from pain is achieved (normally at 200 mg 3–4 times daily); in the majority of patients 200 mg 3 or 4 times a day maintains a pain-free state; then reduce gradually to the lowest possible maintenance level; in elderly patients (65 years or above) an initial dose of 100 mg twice daily is recommended. PROPHYLAXIS OF MANIC DEPRESSIVE PSYCHOSIS in patients unresponsive to lithium: initial 400 mg daily in divided doses, increasing gradually until symptoms are controlled or a total of 1200 mg in divided doses is reached; usual range 400–600 mg daily in divided doses. ELDERLY: because of the potential for drug interactions, the dosage should be selected with caution in patients 65 years or above. POLYTHERAPY: wherever possible antiepileptics should be prescribed as sole therapy; when carbamazepine is added to existing antiepileptic therapy this should be done gradually while maintaining or, if necessary, adapting the dosage of the other antiepileptic(s). Source §4.4, §4.6 and §4.8 were truncated at the source-fetch limit and §4.5 was not retrieved.

dosePerKg is left null because the SPC states a RANGE, not a single per-kg figure. VERBATIM §4.2, children (4 weeks of age or above) and adolescents: 'It is advised that with all formulations of carbamazepine, a gradually increasing dosage scheme is used and this should be adjusted to suit the needs of the individual patient. Usual dosage 10-20 mg/kg bodyweight daily in several divided doses.' AGE-BAND TOTAL DAILY DOSES stated for this 100 mg/5 ml suspension: 4 weeks up to 1 year — 100 to 200 mg daily (5–10 ml liquid per day); 1–5 years — 200 to 400 mg daily (10–20 ml per day); 5–10 years — 400 to 600 mg daily (20–30 ml per day in divided doses); 10–15 years — 600 to 1000 mg daily (30–50 ml per day in several divided doses); over 15 years — 800 to 1200 mg daily (same as the adult dose). CONTRAINDICATED UNDER 4 WEEKS: 'Carbamazepine oral suspension is contraindicated in children less than 4 weeks of age because of the potential adverse effects/toxicity from the excipient propylene glycol' (§4.3). Start low and increase slowly because the suspension gives higher peak levels than the same dose in tablet form. Verify all under-18 dosing against a children's formulary.