Tegretol

What is it?

A dibenzazepine preparation available as scored, white tablets in 3 strengths, all containing carbamazepine; 100mg and 200mg tablets are marked with strength and name. 400mg oblong tablets with company and tablet name. Also, TEGRETOL CHEWTABS, available as square, pale orange chewable tablets marked with T, tablet strength and name, containing 100mg and 200mg of carbamazepine. A/so, TEGRETOL RETARD, available as continuous-release, orange, scored, oblong tablets marked CG and HC containing 200mg of carbamazepine and scored, brown, continuous-release tablets containing 400mg of carbamazepine, marked CG ENE. Also, TEGRETOL LIQUID, a sugar-free liquid containing 100mg of carbamazepine per 5ml. Also, TEGRETOL SUPPOSITORIES, available in 2 strengths containing 125mg and 250mg of carbamazepine.

Medical Uses

All preparations except suppositories: prevention of manic depressive psychosis which does not respond to therapy with lithium, seizures, (generalised tonic clonic and partial), trigeininal neuralgia. Suppositories, seizures only.

Dosage

Adults, manic depressive psychosis, start with 400mng each day in divided doses and then gradually increase dose until the symptoms are controlled, with a maximum of 1.6g each day in divided doses. The usual dose is in the order of 400 to 600mg daily. Seizures, start with 100 to 200mg once or twice each day increasing gradually to 800mg to 1.2g daily with a maximum of 1.6g in divided doses. Suppositories, short-term use, for up to 7 days, when oral preparations cannot be used; if changing from oral preparations, dose should be increased by 25% to a maximum dose of 250mg every 6 hours. Trigeminal neuralgia, 100mg once or twice each day to begin with then gradually increase dose until control is achieved, usually in the order of 600 to 800mg daily in divided doses. The maximum daily dose is 1.6g each day in divided doses. Children, seizures only, aged 12 months and under, 100 to 200mg; aged 1 to 5 years, 200 to 400mg; aged 5 to 10 years, 400 to 600mg; aged 10 to 15 years, 600mg to Ig. All as daily divided doses with liquid for babies under 12 months and liquid or chewtabs for children aged up to 5 years. Suppositories, same indications as for adults with dosages appropriate to age of child.

Special Care

Elderly patients, pregnancy, breastfeeding, previous psychotic illness, glaucoma, liver, kidney or heart disease. Tests for blood urea nitrogen (BUN), analysis of urine, blood counts and liver function should be carried out before treatment starts and then regularly during period of therapy.

Avoid Use

Previous porphyria (inherited metabolic disorder involving porphyrins) or depression of bone marrow, abnormalities in atrioventricular conduction (heart conduction block).

Possible Drug and Food Interactions

Maois, alcohol, azole antifungals, combined oral contraceptives, rifampicin, viloxazine, oral anticoagulants, steroids, lithium, fluoxetine, mefloquine, tibolone, loratadine, cimetidine, nefazodone, frusemide, felodipine, nicotinamide, risperidone, cyclosporin, metraclopramide, inducers or inhibitors of CYP450 3A4, non-depolarising muscle relaxants, isotretinoin, thioridazine, dextropropoxyphene, cytotoxics, terfenadine, toremifene, doxycycline, gestrinone, isoniazid, olanzapine, haloperidol, protease inhibitors, cimetidine, calcium antagonists, benzodiazepines, digoxin, tramadol, danazol, theophylline, acetazolamide, anticonvulsants, hydrochlorothiazide, viloxazine, macrolide antibiotics, thyroxine, clozapine, St John's Wort, TCADs, methadone, paracetamol.

Known Side Effects

Double vision, allergic skin effects, dry mouth, dizziness, gastrointestinal upset, low blood sodium levels, drowsiness, fluid retention, loss of co-ordination, raised liver function tests, blood changes. In rare cases, toxic epidermal necrolysis (a rare skin disease producing exfoliation), multi-organ hypersensitivity disorder, hepatitis, Stevens Johnson syndrome, disturbances in heart conduction, jaundice.