With the patent on producing Nifedipine expired there is no motivation for pharmaceutical companies to search for further uses of the drug (Malecontraceptives). It is because the companies would not be able to patent the drug that they could not make any money off of Nifedipine as a male contraceptive leading to a sharp decline in funding. With no funding researchers are unable to conduct further research.
Dr. Susan Benoff is a leading expert in male contraception and has been able to privately fund most of her research. She has some patents that are looking at Mannose lectin-correlated infertility and a fluorescent labeling system to look at mannose lectin composition on the surface of sperm cells. Using calcium channel blockers to effect the composition of the plasma membrane and Mannose lectin levels, Dr. Benoff is continuing to pursue Nifedipine as a possible male contraceptive.