Safety and Pharmacokinetics of PSD502 in Healthy Chinese Male and Female Volunteers: Two Randomized, Double-Blind, Placebo-Controlled, Phase I Trials

BACKGROUND AND OBJECTIVE

PSD502 is a metered-dose spray for premature ejaculation. The two trials aimed to evaluate the safety and pharmacokinetics of PSD502 in healthy Chinese male and female individuals.

METHODS

Two phase I, randomized, double-blind, placebo-controlled trials were conducted in men (Trial 1) and women (Trial 2). The participants were randomized 3:1 to receive PSD502 (7.5 mg of lidocaine and 2.5 mg of prilocaine per spray) or a placebo. For male individuals, a single dose (three sprays) once daily was applied to the glans penis for 21 days except for nine sprays (three doses) on days 7 and 14, 4 h apart for each dose. For female individuals, two sprays were applied to the vagina and one to the cervix once daily for 7 days. The primary endpoint was safety. Pharmacokinetics analysis was also performed.

RESULTS

Twenty-four male and 24 female individuals were recruited. Treatment-emergent adverse events occurred in 38.9% (7/18) of male individuals and 66.7% (12/18) of female individuals in the PSD502 group, respectively. Both trials reported 50.0% (3/6) treatment-emergent adverse events for the placebo. No grade ≥ 3 treatment-emergent adverse events, serious adverse events, or treatment-emergent adverse events leading to early withdrawal or discontinuation occurred. After consecutive applications, lidocaine and prilocaine cleared rapidly in both trials. Plasma concentrations exhibited high inter-individual variability. The maximum plasma concentrations of active ingredients were far below the anticipated minimum toxic concentrations. The area under the plasma concentration-time curve of metabolites were ≤ 20% of the parent drugs. No clinically significant accumulations were observed in the two trials.

CONCLUSIONS

PSD502 was well tolerated and showed low plasma concentrations in healthy Chinese male and female individuals.

Comparison of the efficacy of two different local anesthetics in inferior turbinate reduction

PURPOSE

The present study compares the local anesthetic efficacy of EMLA® cream and lidocaine injection used in the radiofrequency reduction of the inferior turbinate.

METHODS

The study included a total of 124 patients with inferior turbinate hypertrophy and who underwent turbinate reduction under local anesthesia. The operations were performed 15 min after a lidocaine injection and 30 min after EMLA cream application. The respondent patients were asked to interpret such situations as intraoperative pain, discomfort during the procedure, choking sensation and difficulty swallowing using the Visual Analogue Scale (VAS).

RESULTS

The EMLA cream patients (Group A) were found to have a lower level of discomfort, choking sensation and difficulty swallowing than the lidocaine patients (Group B), while there was no substantial difference in pain between the two groups.

CONCLUSIONS

It is concluded that EMLA® cream is an effective alternative to lidocaine injection during inferior turbinate reduction procedures.

[Intoxication with prilocaine/lidocaine can cause serious methemoglobinemia]

Prilocaine/lidocaine is widely used as local anesthetic in children for cannulation and minor surgical procedures. Usually it is unproblematic but it is important to adhere to recommended dose to avoid serious complications. Excessive amount of prilocaine/lidocaine, large application area, prolonged application time or repeated application can, especially in infants, cause methemoglobinemia with clinical symptoms. In severe cases intensive care and antidote treatment with Methylene blue may be required. We report three infants who were overdosed with prilocaine/lidocaine, two of them due to incorrect use after circumcision and one premature baby where prilocaine/lidocaine was not removed in time. Two of the babies had MetHb levels > 33% and were seriously affected with hypoxia, tachycardia and fatigue. After Methylene blue was given the infants recovered within 15 minutes and MetHb levels returned to normal.