Nifedipine
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| Clinical data | |
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| Pregnancy category |
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| Routes of administration | Oral |
| ATC code | |
| Legal status | |
| Legal status | |
| Pharmacokinetic data | |
| Bioavailability | 45-56% |
| Protein binding | 92-98% |
| Metabolism | Gastrointestinal, Hepatic |
| Elimination half-life | 2 hours |
| Excretion | Renal: >50%, Biliary: 5-15% |
| Identifiers | |
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| CAS Number | |
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| CompTox Dashboard (EPA) | |
| ECHA InfoCard | 100.040.529 |
| Chemical and physical data | |
| Formula | C17H18N2O6 |
| Molar mass | 346.335 g/mol |
| Melting point | 6 °C (43 °F) |
Nifedipine (brand name Adalat and Procardia) is a dihydropyridine calcium channel blocker. Its main uses are in angina pectoris (especially Prinzmetal's angina) and hypertension, although a large number of other uses have recently been found for this agent, such as Raynaud's phenomenon, premature labor, and painful spasms of the esophagus in cancer patients.
Nifedipine lowers the blood pressure rapidly, and patients are commonly warned they may feel dizzy or faint after taking the first few doses. Tachycardia (fast heart rate) may occur as a reaction. These problems are much less frequent in the sustained-release preparations of nifedipine (such as Adalat OROS).
Nifedipine should be taken on an empty stomach, and patients are warned not to consume anything containing grapefruit or grapefruit juice, as it lowers CYP3A4 activity (the enzyme that digests nifedipine) and may lead to increased levels of nifedipine or other medications that are metabolised by CYP3A4 in the blood.
The rapid-release capsule form of Nifedipine is commonly prescribed to patients treated with irreversible MAOIs, as a safety measure. In the case of a hypertensive crisis (typically presented as palpitations, extreme headache and stiff neck), a capsule is bitten open, put under the tongue for 15 seconds, and then swallowed. The reaction generally starts to abate after 20-30 minutes. As always, this is an emergency measure, and not to be substituted for dietary restrictions and proper emergency medical care.
Male Contraceptive Effects
Nifedipine and other calcium-channel blockers may interfere with the normal development of sperm, potentially reducing the fertility of men who take it. It has been studied by at least one researcher as a potential reversible male contraceptive, [1] however, it is not being actively pursued as a contraceptive by any major pharmaceutical companies, possibly because of perceptions that publicizing its contraceptive effects would negatively impact sales as a blood-pressure medication, or because an expired patent and the availability of inexpensive generics makes new uses an unappealing financial prospect.[2]
At least one case of possible Nifedipine-induced infertility has been reported in the literature. [3]. Couples who are having difficulty conceiving should consult their doctor if the man is taking nifedipine.
The apparent contraceptive mechanism is an inhibition of the normal mannose lectin coating of the spermatozoa's outer membrane; this coating is necessary for correct binding with the egg. This may be caused when a greater-than-normal amount of cholesterol is integrated into the membrane, stiffening the membrane and preventing normal outward migration of mannose from the interior.[2][3]
References
- Enders, G. "Clinical approaches to male infertility with a case report of possible nifedipine-induced sperm dysfunction." J Am Board Fam Pract. 1997 Mar-Apr;10(2):131-6.
- Nifedipine at MaleContraceptives.org [4]. Retrieved October 10, 2006
- Nifedipine - rxlist.com
- MedlinePlus DrugInfo medmaster-a684028
- ^ "FDA-sourced list of all drugs with black box warnings (Use Download Full Results and View Query links.)". nctr-crs.fda.gov. FDA. Retrieved 22 Oct 2023.
- ^ Goodwin, LO, NB Leeds, I Hurley, FS Mandel, RG Pergolissi and S Benoff (1997) “Isolation and characterization of the primary structure of testis-specific L-type calcium channel: implications for contraception.” Molecular Human Reproduction 3(3): 255-68.
- ^ Benoff, S (1998) “Voltage dependent calcium channels in mammalian spermatozoa.” Frontiers in Bioscience 3: D1220-40.
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