CARBAMAZEPINE
Indications: focal and 1°/2° generalised T/C seizures, trigeminal neuralgia, bipolar disorder
unresponsive to lithium (prophylaxis), acute alcohol withdrawal (adjunct) (unlicensed), diabetic
neuropathy (unlicensed)
Oral liquid – retain rectally for at least 2 hours P/R tablets – can be halved but not chewed
AVOID in AV conduction abnormalities, H/O bone marrow depression
CAUTION in cardiac disease, absence/myoclonic seizures (exacerbation), skin reaction, angle-
closure glaucoma, H/O haematological reactions to other drugs
Vitamin D supplements – consider if Pt is immobilised for long periods or inadequate sun
exposure or dietary intake of calcium
Blood, hepatic or skin disorders – withdraw ASAP if liver dysfunction occurs. Severe,
progressive leucopenia requires withdrawal. Pts must report signs and seek attention if fever,
rash, mouth ulcers, bruising or bleeding occurs
Risk of antiepileptic hypersensitivity syndrome (AHS) – caution cross-sensitivity also with
oxcarbazepine and phenytoin
Pre-Tx screening – test for HLA-B*1502 allele in Pts of Han Chinese or Thai origin (avoid unless no
alternative – risk of SJS in presence of allele)
SIDE EFFECTS = hyponatraemia, leucopenia, weight gain, oedema, thrombocytopenia, drowsiness,
dry mouth, fluid imbalance, tics, tremor, human herpesvirus 6 infection re-activation (FNK)
o Dose related SEs most common at start of Tx and in elderly = headache, ataxia, drowsiness, N/V,
blurred vision, dizziness, allergic skin reactions
MONITORING:
o Aim = 4-12mg/L (20-50micromol/L) measured after 1-2 weeks
o Blood counts, hepatic and renal function
CESSATION – when stopping for bipolar disorder, reduce gradually over at least 4 weeks
INTERACTIONS:
1. As an INDUCER = reduces the efficacy of other drugs
2. Hyponatraemia – with NSAIDs, loop/thiazide diuretics, TCAs, SSRIs, trimethoprim
3. Hepatotoxicity – with alcohol, statins, tetracyclines, penicillins, fluconazole, paracetamol
, AMIODARONE
INDICATIONS: arrythmias, ventricular fibrillation or pulseless ventricular tachycardia
MHRA/CHM (2015) – risk of severe bradycardia and heart block with sofosbuvir, etc
AVOID in iodine allergy, SA heart block, sinus bradycardia and thyroid dysfunction
CAUTION in conduction disturbances, elderly, heart failure, hypokalaemia, severe bradycardia
Photosensitivity – shield skin during Tx and for several months post Tx. Use a wide-spec
sunscreen to protect against long-wave UV and visible light
SIDE EFFECTS = constipation, hyperthyroidism, respiratory disorders, photosensitivity, hypotension
(IV use), myopathy (reversible), peripheral neuropathy (reversible), grey pigmentation
Corneal microdeposits – reversible on withdrawal. If vision is impaired or if optic
neuritis/neuropathy occurs, stop to prevent blindness
Thyroid function – both hypo/hyper can occur. Hypo can be treated with replacement therapy
without stopping amiodarone if it’s essential
Hepatotoxicity – discontinue if signs of liver disease occur
Pulmonary toxicity – pneumonitis should always be suspected if new or progressive shortness of
breath or cough develops
PREGNANCY/BF – risk of neonatal goitre hence use only if no alternative available. Avoid in BF
MONITORING
o TFTs – before Tx and every 6 months
o Absence of hyperthyroidism = raised T4 hence measure T3, T4 and TSH
o Thyrotoxicosis = raised T3 and T4 with low TSH
o LFTs – before Tx and every 6 months
o Serum potassium and chest x-ray– before Tx
o With antivirals – monitor for bradycardia (for 48hrs if high risk) even if amiodarone stopped.
Recognise and report signs like shortness of breath, light-headedness, palpitations, fainting,
chest pain or unusual tiredness
INTERACTIONS: (long half-life = interactions occur weeks/months post stopping Tx)
1. As an INHIBITOR = reduces the efficacy of other drugs
2. Bradycardia – with beta-blockers, digoxin, donepezil, rivastigmine, MAOIs and CCBs
3. Prolonged QT interval – with SSRIs, macrolides, fluconazole, haloperidol, hydroxyzine, lithium,
ondansetron, quinine, sildenafil, sotalol and SNRIs
4. Hypokalaemia – with aminophylline, steroids, thiazide diuretics, loop diuretics, beta-2 agonists
and theophylline
