A high-performance liquid chromatography–diode array detector method (HPLC-DAD) was developed and validated for the determination of tramadol in human saliva. Samples of saliva were prepared utilizing liquid–liquid extraction with hexane-ethyl acetate (4: 1, v/v). Propranolol was used as an internal standard (IS). The linear range and average recovery of tramadol were 0.25–4.00 µg/mL and 94.70%, respectively. The intra-and inter-assay precisions at low, intermediate and high concentrations were within 1.40–9.79% and 0.77–3.98%, respectively. Intra-and inter-assay accuracies were within 98.50–107.13% and 100.44–103.89%, respectively. The proposed method was successfully applied to determine tramadol in saliva concentrations in three healthy volunteers for 24 hours after administration of 100 mg oral doses of tramadol.

Oxidative stress has been proven to be involved in cisplatin (CP)-induced toxicity. The present study was designed to evaluate the antioxidant activity of Vit C, N,N0-diphenyl-p-phenylenediamine (DPPD) and Lcysteine against CP-induced testicular oxidative damage in rats. Our data indicated significant increases in lipid peroxides (LPO), total peroxides and superoxide anion levels in testes of rats treated with CP (2 mg/kg/week, for 4 weeks) that was associated with a significant reduction in the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST). The contents of glutathione (GSH), Vit E and Vit C were significantly lower in CP treated testes compared with these of control. The co-administration of CP with DPPD or L-cysteine significantly reduced the elevation in LPO, however the co-administration of CP with Vit C, DPPD or L-cysteine reduced the effect of CP on superoxide anion and antioxidant enzymes and also on the antioxidants contents. The administration of Vit C, DPPD or L-cysteine before CP injection improved the histological pictures and reduced the number of apoptotic cells and DPPD was more efficient. In conclusion, DPPD is a potent antioxidant, against CP-induced testicular oxidative damage, as compared with Vit C and L-cysteine.