Pharmacokinetic Alteration of Pethidine in Patients Following Lower-Limb Orthopedic Surgery and its Relationship with the Intensity of Pain in these Patients.

The aim of the present study was to investigate possible relationship between blood levels of pethidine and intensity of pain in patients following orthopedic surgery in inferior limb. Twelve patients who underwent orthopedic surgery of the lower limbs and were classified as class I patients (according to the American society of anesthesiologists physical status classification) were included in the present single arm study. They were all between the age range of 18 and 35 years, having full consciousness and experiencing post-operative pain. Those undergoing emergency surgical operations and having abnormal paraclinical tests were excluded from the study. The study was conducted at Sina hospital. After the surgery, following the transference of the patient to the recovery section, 25 mg pethidine was injected intravenously using standard method for local (spinal) anesthesia for pain control. Then, 5, 30, 60 and 180 minutes after injection, blood samples were taken and concentration of pethidine in blood samples were measured by HPLC method. Moreover, patients’ pain intensity was assessed on visual analogue scales. As secondary outcome measures, any possible adverse drug reactions were monitored. Finally, the possible relationship between pharmacokinetic alteration of pethidine and pain intensity of the patients undergoing lower-limb surgery was calculated.

Vice Chancellor for Research Affairs, Islamic Azad University, Pharmaceutical Sciences Branch.