Antares Pharma, Inc. has reported positive results from a multi-centre phase II clinical study evaluating the pharmacokinetic profile of testosterone enanthate administered once-weekly by subcutaneous injection at doses of 50 mg and 100 mg using the Vibex QuickShot auto injector in testosterone deficient adult males.

Twenty nine adult males with hypogonadism (low testosterone) and testosterone blood levels less than 300 ng/dL were randomized into two groups. The first group received 50 mg testosterone enanthate administered subcutaneously with the QuickShot auto injector once weekly for six weeks and the second group received 100 mg of testosterone enanthate using the same device and time sequence. The clinical study followed patients for four weeks after the last dose.

The mean testosterone baseline for the 50 mg group was 214.6 ng/dL and 201.5 ng/dL in the 100 mg group. At week one, both doses produced normal mean total testosterone concentrations at 24 hours post-dose, 434 ng/dL in the 50 mg group and 572 ng/dL in the 100 mg group. During week six of the study when patients were already at steady state pharmacokinetic conditions, the 50 mg and 100 mg groups had average plasma testosterone values within the normal range at 422.4 ng/dL and 895.5 ng/dL, respectively. The study demonstrated rapid restoration, consistent maintenance of normal testosterone levels and dose proportionality of the 50 mg and 100 mg strengths. The onceweekly injection was generally well tolerated. No injection site pain was reported by 28 of 29 patients and 17 patients reported mild to moderate adverse events which according to the investigators were unrelated to the drug or device. There were no deaths, serious adverse events or discontinuations due to adverse events in the study.

Paul K Wotton,  president and chief executive officer, stated, “We are very optimistic about the potential for a self-administered, once weekly subcutaneous dose of testosterone based on the outcome of this study.” Dr Wotton continued, “The administration of testosterone using our proprietary QuickShot device showed that normal testosterone levels can be rapidly restored and then reliably maintained with reduced peak to trough fluctuations relative to those associated with intramuscular injections. Unlike topical treatments for males with hypogonadism, currently approved injectable forms of testosterone do not carry a black box warning for risk of transference, which has been reported  to lead to abnormal development of male sexual characteristics in women and children.”

The proprietary Vibex QuickShot auto injector emphasizes enhanced performance on the attributes contributing most to patients successfully controlling their testosterone deficiency – reliable and consistent blood levels, ease and speed of self-administration, comfort and discretion.  The State-of-the-Art precision engineering of the QuickShot device allows rapid subcutaneous selfadministration of highly viscous drugs such as testosterone and biologics using high spring pressure through a fine gauge needle.  Conventional auto injectors or even a vial, needle and syringe could not inject these drugs efficiently or as fast and easy as the QuickShot device.

Antares Pharma focuses on self-administered parenteral pharmaceutical products and topical gelbased medicines.