Methods	Randomised, double-blind, active controlled, parallel-group, no enrichment Dose escalation every 2 weeks until adequate pain relief obtained or limit of tolerability, to maximum nortriptyline 150 mg daily or gabapentin 2700 mg daily by 4 weeks, then stable dose for 5 weeks (9 weeks in total)
Participants	Postherpetic neuralgia. N = 76, mean age 54 years, 50% women. Pain > 2 months after healing of skin rash. PI at randomisation ≥ 40/100, initial average daily pain score 5.7/10
Interventions	Gabapentin 2700 mg daily (max), n = 38 Nortriptyline 150 mg daily (max), n = 38 Of ‘responders’ ~80% gabapentin took 2700 mg daily, ~66% nortriptyline took 75 mg daily
Outcomes	≥ 50% pain relief over baseline pain ≥ 50% pain relief over (VAS) Adverse events Withdrawals
Notes	Oxford Quality Score: R = 2, DB = 2, W = 1, Total = 5 Sponsored Pfizer/independent
Risk of bias
Item	Authors’ judgement	Description
Allocation concealment?	Yes	“code supplied in sealed envelopes, opened at time of enrolment”, “drugs dispensed in sealed envelopes”
Blinding? All outcomes	Yes	“drugs placed in identical capsules”, “matching placebo of nortriptyline” to blind different dosing schedules
Incomplete outcome data addressed? Efficacy	Unclear	Imputation not mentioned
Size Efficacy	Unclear	76 randomised
Study duration Efficacy	Yes	9 weeks
Outcomes reported	Yes	At least 50% reduction in pain