The early steps in the biosynthesis of steroids of both plants and animals are the same, except that in plants lanosterol is replaced by the related compound cycloartenol, which contains a three-membered ring (C9, C10, C19) in lieu of the nuclear double bond of lanosterol. The side chains of the phytosterols, such as stigmasterol, and of the sterol ergosterol of yeasts and other fungi contain extra carbon atoms that are incorporated in reactions involving S -adenosylmethionine, which donates methyl groups in numerous biological processes. Although most plant tissues contain only traces of cholesterol, this sterol is the biogenetic precursor of such important plant steroids as the sapogenins , glycosides , and alkaloids . Because pregnane derivatives are intermediates in some of these transformations, plants and animals appear to have important features of steroid metabolism in common.
There is limited and inconclusive data on the effect of high body weight/high BMI on the contraceptive efficacy. In three WHO studies no trend for a reduced efficacy with increasing body weight/BMI was observed (Table 1), whereas in the two other studies (Creinin et al., 2006 and Glasier et al., 2010) a reduced contraceptive efficacy was observed with increasing body weight or BMI (Table 2). Both meta-analyses excluded intake later than 72 hours after unprotected intercourse (. off-label use of levonorgestrel) and women who had further acts of unprotected intercourse.
Some FDA regulated products are intended to be used together to achieve their therapeutic or diagnostic effect but do not meet the regulatory definition of a combination product, This can be the case for medical products intended to be used together, for example, syringes marketed for general delivery of unspecified drugs or two or more of the same type of medical product (., a drug and drug, or device and device) that are packaged or labeled for use with one another (., fixed dose combination drugs under 21 CFR ). Similarly, combinations of a medical product with a non-medical product, for example a drug with a dietary supplement, cosmetic, or food, are not combination products.