Table 1.
Commonly used medicines in TN
| Medicine | Daily dose range | Important side effects | Recommendations on use | Comments |
|---|---|---|---|---|
| Carbamazepine | 200 –1600mg | Contraindicated with unpaced AV conduction abnormalities. | Begin with small doses, depending on tolerability. Increase and decrease slowly. | Adverse drug interactions.e.g warfarin. |
| (CBZ) | ||||
| (Evidence rating A - Effective / Should be used) | Neurological side effects (dose related). Hyponatraemia / blood disorders - monitor bloods at regular intervals. SJS/TEN rarely | HLA-B*1502 allele in individuals of Han Chinese or Thai origin - increased risk of SJS/TEN. | ||
| Oxcarbazepine | 300–1200mg | Neurological side effects, hyponatraemia with higher doses. Very rarely blood disorders, SJS/TEN | Use on a four times a day basis | Generally better tolerated than CBZ. |
| (Evidence rating B - Probably effective / Should be considered) | ||||
| Baclofen | 50–80mg | Neurological side effects | Begin very slowly, divided doses. | Withdraw drug slowly to avoid side effects. Useful in patients with MS |
| (Evidence rating C - Possibly effective / may be considered) | ||||
| Lamotrigine | 200–400mg | Neurological side effects, blood disorders, rarely SJS/ TEN. | Initially very slow escalation. Can use in combination with CBZ | Cutaneous reactions common if increase dose too quickly |
| (Evidence rating C - Possibly effective / may be considered) | ||||
| Gabapentin with ropivacaine27 | 1800–3600mg (RCT utilised up to 900mg) + 2ml of mg/ml Ropivicaine | Neurological side effects | Ropivacaine injected weekly into trigger spots | Use of ropivacaine reduced dose of gabapentin required. (Small RCT with newly diagnosed patients likely to go into remission) |
| (Evidence rating C - Possibly effective / may be considered) | ||||
| Medicines not evaluated in Randomised Controlled Trials | ||||
| Phenytoin | 200–300mg | Neurological side effects, blood disorders, rarely SJS/ TEN. | Can use with CBZ. HLA-B*1502 cross reactivity with CBZ. | >300mg can lead to severe side effects |
| Sodium valproate | 600–1200mg | Neurological side effects, blood disorders, rarely hepatic dysfunction. | Monitor liver function for first 6/12. | Often used by Neurologists |
| Pregabalin | 150–600mg | Neurological side effects - dose dependent. Peripheral oedema with higher doses. | Use twice daily, avoid abrupt withdrawal. | Long term cohort study shows promise |
CBZ - carbamazepine
HLA-B*1502 - Human Leukocyte Antigen- B*1502
AV - Atrioventricular
SJS/TEN - Stevens Johnson Syndrome / Toxic Epidermal Necrolysis