Maternal and foetal drug levels after epicutaneous application of a local anaesthetic formulation containing ketocaine for possible use as pain relief in labour.

A local anaesthetic formulation (A 2358) containing ketocaine, a local anaesthetic drug, was applied epicutaneously to the low back. Two compresses soaked with A 2358 were applied for 1 hour in 26 normal labours for relieving referred pain from the low back. The maternal blood ketocaine levels remained low, compared to higher systemic levels reported in other studies. Maternal heart rate and blood pressure were stable during the application time. The mean umbilical vein/maternal vein and umbilical artery/maternal vein concentration ratios were 0.20 +/- 0.10 and 0.21 +/- 0.09. In addition, the foetal heart rate findings and the conditions of the neonates were satisfactory, thus suggesting the foetal safety of this analgesic method.