Four RCTs involving 401 participants were included. Two of these RCTs employed a crossover design (32 participants).
Quality assessment.
The quality score was 3 for two of the studies, and 5 for the other two studies. Methodological limitations of the studies included small sample sizes, non-probability sampling and sparse quantitative data.
All studies reported statistically-significant differences in favour of pilocarpine-stimulated treatment groups. The patients reported improvements in a number of areas, e.g. oral dryness, oral comfort, chewing, and the ability to speak without requiring liquids. There was an apparent time-dependent drug-related benefit noted in two studies, with patients reporting increased improvements after several weeks of pilocarpine treatment.
All studies reported adverse side-effects from pilocarpine, but none were severe. Sixteen per cent of the patients withdrew from the studies. Sweating and urinary frequency were the most common side-effects noted, but headache, rhinitis and abdominal cramping were also reported. In two studies, doses over 5 mg appeared to produce increased side-effects.
When considering both the side-effects and the efficacy of pilocarpine, all studies advocated 5 mg three times a day to be the optimum dose. The data supplied were insufficient to draw any conclusions as to the efficacy of systemic pilocarpine over topical usage.
Publication bias was not assessed, but the authors noted that there was an inherent potential for publication bias.