Norris 1967.

Methods	Randomised, double‐blind cross‐over study of methixene vs placebo. Randomisation method not stated. 1 site (U.K.) Duration: 7 weeks, each period: 3 weeks.
Participants	16 patients: 2 drop‐outs not included in report, 7 female, 7 male. Age: 47‐89 (mean: 67) years. Disease duration: not stated. Disease severity: not specified. Inclusion criteria: Persistent and marked tremor. "Aetiology varied", but not drug‐induced.
Interventions	Cross‐over design: 3 weeks active drug / placebo ‐ 1 week wash‐out ‐ 3 weeks placebo / active drug. Dose increased over 1 week to maximum 3 times 15 mg = 45 mg. Mean dose: apparently 45 mg in all patients. Other antiparkinsonian drugs continued, kept stable.
Outcomes	Tremor activity, measured with own accelerometer, measure: percentage of change. Trend in favour of mehixene, not statistically significant (p>0.1). No definite subjective difference. Neuropsychiatric AE: none. Drop‐outs: 1 unspecified AE on placebo, 1 error in randomisation.
Notes	Tremor only parkinsonian feature studied.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Unclear risk	B ‐ Unclear