Pharmacotherapy Newsletter

Volume 1, Issue 37, 09/28/2009

Question

Does the type of oral contraceptive (birth control pill) used alter the implied risk for developing venous thromboembolism (DVT and pulmonary embolism)?

Answer

Since 1961 when the first case report of venous thromboembolism (VTE) in a nurse who suffered a pulmonary embolism shortly after starting estrogen containing pills was published, a significant number of studies have been done to determine the factors that contributed to this adverse drug event.(1)  It was initially thought that the dose of estrogen was the primary factor when several other case-controlled and cohort studies consistently showed that oral contraceptive use (mainly with high estrogen doses of 50-150 mcg) were associated with an increased risk for VTE.(2-4)  As a result, the dosage of estrogen decreased to doses in the range of 30-35 mcg and more recently have declined even further, to as low as 15-20 mcg.  Subsequent studies were then performed to compare high dose estrogen (i.e., greater than 50 mcg) versus low dose estrogen (i.e., 50 mcg or less) containing oral contraceptives which showed that high dose estrogen conferred a 10-fold greater risk for developing VTE, whereas low dose estrogen conferred a 4-fold risk.(5-7)  However, this did not end the debate.  

In an attempt to improve other clinical markers of hormone replacement, such as...        

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