Contraception being the need of the hour, we have synthesized a few analogues of nifedipine, an L-type calcium channel blocker and evaluated their effects on sperm fertility. The glass transition temperature (T-g) of spermatozoa has been monitored using DSC to characterize the cellular damage due to aging or by external agents. In this paper we report how T-g can be used as a marker to measure infertility caused by external agents. The cellular damage can be due to the cell immobilization or due to the membrane alteration eventually leading to infertility. Results have been supported by measuring the cell motility, metabolism and lipid peroxidation; the well established markers for estimating the sperm fertility. Unlike D-4, nifedipine and analogue D-2 cause sperm cell aging by hampering the motility without causing the membrane damage. This indicates that the damage caused due to D-4 may be irreversible. Thus the present findings demonstrate that D-2 can be a promising candidate as a lead molecule for the development of reversible antifertility agents. (C) 2011 Elsevier B.V. All rights reserved.