Each week we will aim to bring out a concise email that provides 4-5 key pieces of information addressing a specific issue in clinical therapeutics.
This week: Focus on carbamazepine
Carbamazepine is an anticonvulsant medicine that is relatively widely prescribed in the aged care setting. As well as the original therapeutic application for the management of epilepsy, carbamazepine has now come to be widely used as a treatment for various forms of neuropathic pain: examples include the treatment of postherpetic neuralgia and atypical facial pain such as trigeminal neuralgia.
- When used for the management of epilepsy, carbamazepine is dosed according to the principles of therapeutic drug monitoring. The drug is administered in divided doses (2-3 times a day), with the total daily dose adjusted in accordance with the results of the measurement of the serum concentration of the drug.
- If used for the management of neuropathic pain, therapeutic drug monitoring is less useful, and the dose is generally adjusted on the basis of efficacy and tolerability. Older people are often more sensitive to adverse effects associated with this drug, and so a conservative approach involving slow initial dose titration is best.
- Adverse effects frequently encountered issues include hyponatremia secondary to SIADH (reflected in a low serum sodium), as well as drug induced vitamin D deficiency, and elevations of liver function tests.
- As a powerful inducer of hepatic enzymes, carbamazepine is frequently implicated in clinically significant drug interactions, where the effects of other medications (for example anticoagulants) may be diminished as result of carbamazepine treatment.
Please consider these issues when preparing or interpreting RMMR reports or education sessions. Contributions of content or suggested topics are welcome and should be sent directly to firstname.lastname@example.org.