Phenytoin and carbamazepine in trigeminal neuralgia: marketing-based versus evidence-based treatment

Phenytoin and carbamazepine in trigeminal neuralgia: marketing-based versus evidence-based treatment Jan M Keppel Hesselink,1 Michael E Schatman2,3 1Institute for Neuropathic Pain, Bosch en Duin, the Netherlands; 2Department of Public Health and Community Medicine, Tufts University School of Medicine, Boston, MA, USA; 3Boston Pain Care, Waltham, MA, USAIntroductionMost review articles support carbamazepine as a first-line pharmacotherapy for idiopathic trigeminal neuralgia.1–3 However, the empirical support for this recommendation is somewhat suspect. Phenytoin, as the prototype for all anticonvulsants, was already positioned as an analgesic compound 70 years ago. Since these initial findings, the data that have been gathered have supported the use of anticonvulsants as painkillers – from phenytoin up to and including more recent anticonvulsants such as gabapentin and pregabalin. Since 1942, a number of papers supported phenytoin's therapeutic effects in trigeminal neuralgia (Table 1). The introduction of carbamazepine in 1962 by Geigy shifted the interest of neurologists from phenytoin as a treatment for trigeminal neuralgia to carbamazepine, without sound scientific evidence. To date, no convincing randomized controlled trials (RCTs) have been published supporting the role of carbamazepine in trigeminal neuralgia, and we could not identify a single study comparing the effects of phenytoin with those of carbamazepine. Accordingly, phenytoin should probably be considered more often as a viable therapy for (treatmentresistant) trigeminal neuralgia.