The effect of ammonium glycopyrrolate (Robinul®)-induced xerostomia on oral mucosal wetness and flow of gingival crevicular fluid in humans

The antisialogogue, ammonium glycopyrrolate (Robinul®), was used to reduce the salivary flow rate in healthy individuals with normal salivary function to determine whether the dry-mouth symptoms and reduced amounts and patterns of oral mucosal wetness found previously in hyposalivators could be induced by this means. After baseline measurements, the drug was given to 10 healthy volunteers and their resting whole-saliva flow rate was measured at 0, 15, 60, 105 and 150 min thereafter. At the same times, the thickness of the layer of residual mucosal saliva (a measure of residual mucosal wetness) at each of 22 intraoral sites was also determined. The saliva flow rate fell from a mean of 0.45 ± 0.07 ml/min to a mean of 0.05+ 0.02 ml/mm by 1 h and slowly thereafter to a mean of 0.02 ± 0.01 to 0.03 ± 0.01 ml/min for the remainder of the experiment. Onset of dryness symptoms was observed approx. 30 min after giving the drug. Simultaneously, the residual saliva at each of the 22 sites teted decreased to a thickness level previously found in patients with hyposalivation and who exhibited an intense feeling of dry mouth. Despite these decreases in thickness, the pattern of residual mucosal wetness throughout the mouth remained more or less unchanged. As in earlier studies, wetness was least on the hard palate and highest on the posterior dorsum of the tongue. An altered taste of the residual saliva in the mouth and an increased feeling of roughness as the tongue was passed over labial and buccal mucosal surfaces were noted. The amount of gingival crevicular fluid (GCF) in 12 gingival sites in each of the participants was also measured. Unlike the reduction in salivary flow, changes in GCF over the 150 min of the study were negligible. From this it was concluded that GCF could contribute much more to the oral fluids in dry-mouth than in normal individuals, especially when there is greater gingival inflammation.