How Does It Work?

Nifedipine belongs to a group of drugs called calcium channel blockers (Malecontraceptives). Nifedipine is a non-competitive inhibitor of Ca2+ ATPase enzyme and this is accompanied by a decrease in spermatozoa motility to the point that they are considered immobile (Kanwar et. al). Light microscopy has revealed changes in both the head and the tail. Looking at Figure 1 it can be seen in clear detail that the sperm tail is coiled after 30 minutes of incubation with 100 um of Nifedipine (Kanwar et al.). The results show an inability for the flagellum like movement making sperm unable to move up the vaginal cavity and never reach the ovulated egg.

Figure 1. Picture below shows a sperm that has a coiled tail. The above picture shows what control sperm look like, with a long straight tail. The coiled tail is looped around and when compared to the picture above it is seen that coiled tail is not very similar to a control sperm (Kanwar et al.).

Mannose lectin is a surface protein necessary for the sperm to pass through the five layers surrounding the egg(Benoff). Without Mannose lectin a sperm is considered infertile because even if it comes in contact with an egg it will not be able to fertilize it (Benoff). Studies have shown that Nifedipine greatly reduces the amount of Mannose lectin on the surface of sperm, yet its exact mechanism of accomplishing it has not yet been identified (Benoff). A hypothesis being proposed is that Nifedipine decreases the amount of Mannose lectin on the surface of the sperm because Nifedipine increases the concentration of cholesterol in the plasma membrane making it more rigid and incapable of Mannose lectin moving to the surface from deeper membranes (Malecontraceptives).

Figure 2. Using scanning electron microscopy it is seen that Nifedipine treated sperm have coiled tails making them immobile and also have ruptured plasma membranes (Kanwar et al.).

Rupturing of the plasma membrane on the head and tail of sperm was seen when looking at sperm under a scanning electron microscope. In Figure 2 it is shown that there is both tail coiling and membrane rupture. The rupturing of the plasma membrane is due to the phospholipid concentration in the plasma membrane decreasing to the point it is no longer structurally sound and breaks apart.

There was a full reversal in fertility after 2-3 months of being off Nifedipine (Benoff). This is capable because exposure to Nefidipine does not cause permanent change in how sperm are developed. After the drug is fully removed from the body the new sperm will grow to be fully functioning. The 2-3 month delay is due to the fact that it takes a sperm that length of time to travel through the male reproductive tract and undergo Spermatogenesis.

Next: Side Effects


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