Buffered papaverine facilitates passage of intratympanic dexamethasone to the inner ear

Abstract

Conclusion. We conclude that when papaverine is intratympanically administered together with dexamethasone after buffering, passage of dexamethasone to the inner ear is increased. Objective. To determine the influences of papaverine and buffered papaverine on passage of dexamethasone administered intratympanically to the inner ear. Materials and methods. Twenty-seven Vienna white rabbits were divided into five groups: eight received intratympanic dexamethasone (4 mg/ml) (group 1), seven received intratympanic papaverine (10 mg/ml) + dexamethasone (2 mg/ml) (group 2), six received buffered (with sodium bicarbonate 8.4%) intratympanic papaverine (7.5 mg/ml) + dexamethasone (1.5 mg/ml) (group 3), three had basal cortisol levels in venous blood and perilymph measured (group 4), and three received intravenous papaverine + dexamethasone (group 5). At 1 h after the administration of the drugs, dexamethasone levels in ipsilateral and contralateral perilymph and venous blood were measured by radioimmunoassay. Results. Animals in group 3 demonstrated the highest levels of ipsilateral perilymph dexamethasone. Ipsilateral perilymph levels were significantly higher in groups 1 and 3 than they were in the other groups (p<0.05). Although the perilymph levels observed in animals in group 2 were slightly higher than those in group 4, no significant difference existed (p = 0.160).

• Papaverine
• dexamethasone
• intratympanic
• buffering