"What are birth control pills and how do they work?
Birth control pills are also known as oral contraceptives (OCs) or, simply, “the pill.” They offer protection against pregnancy by blocking the union of sperm and egg, thereby prevent"...
An increased risk of the following serious adverse reactions has been associated with the use of oral contraceptives (See WARNINGS section).
The following adverse reactions have been reported in patients receiving oral contraceptives and are believed to be drug-related:
The following adverse reactions have been reported in users of oral contraceptives and the association has been neither confirmed nor refuted:
Read the Tri-Sprintec (norgestimate and ethinyl estradiol tablets-triphasic regimen) Side Effects Center for a complete guide to possible side effects
Reduced efficacy and increased incidence of breakthrough bleeding and menstrual irregularities have been associated with concomitant use of rifampin. A similar association, though less marked, has been suggested with barbiturates, phenylbutazone, phenytoin sodium, carbamazepine, and possibly with griseofulvin, ampicillin and tetracyclines.72
Interactions with Laboratory Tests
- Increased prothrombin and factors VII, VIII, IX, and X; decreased antithrombin 3; increased norepinephrine-induced platelet aggregability.
- Increased thyroid binding globulin (TBG) leading to increased circulating total thyroid hormone, as measured by protein-bound iodine (PBI), T4 by column or by radioimmunoassay. Free T3 resin uptake is decreased, reflecting the elevated TBG, free T4 concentration is unaltered.
- Other binding proteins may be elevated in serum.
- Sex hormone binding globulins are increased and result in elevated levels of total circulating sex steroids; however, free or biologically active levels either decrease or remain unchanged.
- High-density lipoprotein (HDL-C) and total cholesterol (Total-C) may be increased, low-density lipoprotein (LDL-C) may be increased or decreased, while LDL-C/HDL-C ratio may be decreased and triglycerides may be unchanged.
- Glucose tolerance may be decreased.
- Serum folate levels may be depressed by oral contraceptive therapy. This may be of clinical significance if a woman becomes pregnant shortly after discontinuing oral contraceptives.
72. Stockley I. Interactions with oral contraceptives. J Pharm 1976; 216:140-143.
Read the Tri-Sprintec Drug Interactions Center for a complete guide to possible interactions
Last reviewed on RxList: 12/10/2008
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