While the actual labeling information has yet to on 4/22/10 that a press release issued by Bayer "makes us wonder whether Bayer is issuing it to warn doctors and patients or to attack medical researchers who have suggested that these unique 'fourth generation' pills containing the progestin drospirenone (DRSP) may be unsafe to use."
According to Lamb, Bayer appears to state that the safety profile for Yaz / Yasmin is comparable to that of older birth control pills, while regulators in Europe see a potential for increased risk of blood clotting side effects.
While the proposed change to labeling for the US has yet to be released, Lamb says that the communiqué issued by Bayer ahead of the release gives a hint as to what the updated label will contain:
"A prospective cohort study (EURAS), conducted in Europe, showed the risk of thromboembolism (particularly venous thromboembolism) and death in Yasmin users to be comparable to that of oral contraceptive preparations, including those containing levonorgestrel. Another prospective cohort study (Ingenix), conducted in the USA, also showed a comparable risk of thromboembolism in Yasmin users compared to users of other COCs, including those containing levonorgestrel. In this study, COC comparator groups were selected based on having similar characteristics to those being prescribed Yasmin.
"As part of its evaluation of the risk/benefit of YAZ and Yasmin, the FDA also reviewed data from one case-control study (van Hylckama Vlieg et al.) and one retrospective study (Lidegaard et al.) which suggested that the risk of venous thromboembolism occurring in Yasmin users was between the risk associated with levonorgestrel-containing COCs and desogestrel/gestodene-containing COCs. Based on the FDA's review, the new labels now state that key conclusions from both studies are unreliable:
"With regard to the case-control study, the label indicates that, '…the number of Yasmin cases was very small (1.2% of all cases) making the risk estimates unreliable.'
"Concerning the retrospective cohort study, the label indicates that, 'The relative risk for Yasmin users in the retrospective cohort study was greater than that for users of other COCs when considering women who used the products for less than one year. However, these one-year estimates may not be reliable because the analysis may include women of varying risk levels. Among women who used the product for one to four years, the relative risk was similar for users of Yasmin to that for users of other COCs.'"
Meanwhile, Lamb points out that the latest issue of Drug Safety Update, published in April by the Medicines and Healthcare products Regulatory Agency (MHRA) in Europe included an update on Yasmin, which included the following:
"The incidence of VTE in association with the use of levonorgestrel, desogestrel
and gestodene-containing pills has been studied extensively. Overall, these studies have shown that women who use desogestrel or gestodene-containing pills have a slightly higher risk of developing VTE than those who use levonorgestrel-containing pills. Because Yasmin was licensed relatively recently, fewer studies on its associated risk have been carried out.
"In 2006, the results from two large prospective cohort studies (EURAS and
Ingenix), suggested that the risk of VTE in Yasmin users is comparable with that
for other contraceptives that contain a similar level of oestrogen, including those
containing levonorgestrel. More recently, the results from a Danish cohort study
and a Dutch case-control study have suggested that this risk may be slightly
higher than previously estimated and somewhere between the risk associated with levonorgestrel-containing pills and with desogestrel or gestodene-containing pills (relative risks for the comparison of Yasmin with levonorgestrel-containing pills: 1-64; 95% CI 1-27–2-10 and 1-7; 0-7–3-9, respectively).
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Lamb wonders if Bayer will be allowed to use the phrases "unreliable" and "may not be reliable" with regard to the Lidegaard and Van Hylckama Vlieg publications in Europe, when the updated US label for Yasmin and Yaz is released.
Nonetheless, Lamb suggests a somewhat defiant stance, even in view of a statement from Kemal Malik, MD, Chief Medical Officer at Bayer HealthCare: "At Bayer, our unwavering commitment to our customers' health and well-being is always our first priority and we will continue to provide information which will support health care providers and their patients in making informed decisions about appropriate treatment choices."