Duration of analgesia following application of eutectic mixture of local anaesthetics (EMLA) on genital mucosa.

The topical anaesthetic formulation EMLA cream (eutectic mixture of local anaesthetics) is increasingly used prior to minor painful procedures performed on genital mucosa. The aim of the present study was to gain knowledge about the correlation between duration of application of EMLA and duration of analgesia. Three different application times--5, 10 and 20 min--were investigated in 12 healthy young women. Pin-prick pain thresholds to argon laser stimulation were measured before and after application of EMLA. Repeated measurements were performed until normal sensitivity returned. No significant difference in duration of analgesia was seen between the three application times. However, 10 min application time tended to produce the longest mean duration of analgesia (22.2 min). Surprisingly, a large inter-individual variation in duration of analgesia was seen. Thus, after 10 min application time the shortest duration of sufficient analgesia was 5 min, while the longest was 46 min. On the basis of this work, it seems advisable to start minor surgery on genital mucosa after about 10 min application time, and it is recommended to bear in mind that the duration of analgesia varies and may be very short in some patients.