Comparison of the Efficacy of Two Brands of Triptorelin (Microrelin and Diphereline) in Reducing Prostate-Specific Antigen and Serum Testosterone in Prostate Cancer: A Double-Blinded Randomized Clinical Trial

Background: Gonadotropin-releasing hormone (GnRH) agonists initiate androgen deprivation in treating prostate cancer (PC). Triptorelin is a synthetic GnRH and many of its market brands such as Diphereline have been introduced so far.

Objectives: We compared the efficacy of a sustained-release formulation of Triptorelin (Microrelin), domestically produced in Iran, and compared it with Diphereline in a double-blinded randomized clinical trial.

Patients and methods: Patients were randomly assigned to Group A (Microrelin S.R. 3.75 mg, Pooyesh Darou, Iran) and Group B (Diphereline S.R. 3.75 mg, IPSEN, France). Each patient received monthly intramuscular injections. Prostate-specific antigen (PSA) and circulatory testosterone were measured at baseline and after one, 3, and 6 months.

Results: Each group contained 40 patients. In Group A, PSA was reduced from 75.78 ± 72.43 ng/mL to 1.93 ± 1.40 ng/mL after 6 months and testosterone was reduced from 3.50 ± 1.12 nmol/L to 0.81 ± 0.05 nmol/L. There was no significant difference between the efficacy of Microrelin and Diphereline. Two patients in the Microrelin Group and one patient in the Diphereline Group failed to reach medical castration (testosterone < 1.7 nmol/L), which illustrates that the power of Microrelin and Dipherelin in initiating medical castration is about 95% and 97.5%, respectively.

Conclusions: Our study showed that Microrelin is as effective as Diphereline in reducing PSA and testosterone and can be recommended to initiate medical castration in patients with PC.