Trestolone is a synthetic androgen that inhibits the release of follicle-stimulating hormone and impairs spermatogenesis. Luteinizing hormone is also suppressed, which cuts production of testosterone. The azoospermia and oligospermia are reversible after discontinuation of trestolone. Trestolone has androgenic and anabolic properties and loss of secondary sex characteristics is not seen. Like testosterone, trestolone undergoes enzymatic aromatization to an estrogen. The use of trestolone instead of testosterone for androgen replacement therapy could have health-promoting effects by reducing the occurrence of prostate disease. Trestolone had been in phase II clinical trial for the andropause control. However, this development was discontinued.

Orbofiban was developed as an orally active glycoprotein IIb/IIIa antagonist. By 2001, this drug had progressed to phase III clinical trials. Unfortunately, was found that orbofiban induced thrombocytopenia and thrombosis. In addition, despite no significant excess risk of intracranial hemorrhage, orbofiban was not effective in preventing ischemic stroke or transient ischemic attack. Besides, the use of this drug had led to an increase in mortality. Based on all these results further development of this drug was discontinued.

DAPTA (D-ala-peptide T-amide) is a synthetic peptide that prevents HIV entry by blocking binding of HIV gp120 protein with CCR5 receptor. In a small clinical study of internasal formulation of DAPTA in long-term infected HIV patients, administration of DAPTA led to decrease in the amount of virus isolated from white blood cells, an increase in gamma-interferon secreting T-cells in the absense of drug-related toxicity. In another clinical study DAPTA in combination with antiretroviral therapy reduced the peripheral (plasma and serum) viral load, but did not reduce the CSF viral load.

Teverelix is a polypeptide gonadotropin-releasing hormone (GnRH) antagonist which was being developed by Ardana Bioscience for the treatment of prostate cancer and benign prostatic hyperplasia. Compared with other GnRH antagonists, Teverelix is characterized by relatively good water solubility, little in vitro aggregation, and low histamine-releasing potency, with a dose that produces the halfmaximal response. In preclinical studies, Teverelix has been shown to exert antiovulatory activity. In phase I clinical trials Teverelix shows pronounced luteinizing hormone and testosterone suppressive effects after single subcutaneous doses in healthy men.