Once a potency assay is developed, the sponsor needs to perform a method qualification or validation to demonstrate suitability for intended use. Method qualification/validation also often follows a “phase appropriate” approach. During the early phase of clinical trials, the potency method should at minimum be qualified to demonstrate sufficient accuracy, precision, linearity, and range. The focus on accuracy and precision ensures meaningful interpretation of dose escalation studies. Comprehensive method validation should be implemented as the product moves into Phase III clinical trials and in anticipation of commercialization. A late phase validation study is typically more extensive than that of an early phase qualification and performed under a written protocol that clearly defines the scope of the validation, the target acceptance criteria, and data analysis plan. Multiple analysts and instruments are often employed, and the number of necessary assay runs is justified based on assay variability and intrinsic bias (if known). Method accuracy can be established by testing a sample with known relative potency prepared from the reference standard. In addition, representative routine sample types (drug substance, drug product, etc) should also be tested to confirm suitability of sample handling procedures and method precision. Representative degraded samples—obtained through long term or forced degradation studies—are also frequently included for testing during method validation to confirm the method’s stability-indicating property. Although method robustness may have been established using results generated during method development, a Design of Experiment can often be included within the validation to demonstrate tolerance to varying critical assay conditions.
Epidemiologic studies indicate that the risk of complications with oral contraceptive use is related to the steroid content and potency of the various formulations. This paper summarizes human data in which potencies of progestins in oral contraceptives can be compared. Data on delay of menses and endometrial subnuclear vacuolization, an indirect assessment of glycogen deposition, are presented. The relative effects of various progestins on serum lipids and lipoproteins are also summarized. The object of this review is to examine the available scientific evidence which generally supports the conclusion that there is a marked similarity of potency of the dose of various progestins used in many of the formulations currently available in the . The progestins norethindrone, norethindrone acetate and ethynodiol diacetate are roughly equivalent in potency while norgestrel is roughly five to ten times and levonorgestrel ten to 20 times as potent.
Water vapour has a profound infrared absorption spectrum with more and broader absorption bands than CO 2 , and also absorbs non-zero amounts of radiation in its low absorbing spectral regions,  (see greenhouse gas (GHG)), its GWP is therefore difficult to calculate. Further, its concentration in the atmosphere depends on air temperature and water availability; using a global average temperature of ~16 °C, for example, creates an average humidity of ~18,000ppm at sea level (CO 2 is ~400ppm  and so concentrations of [H 2 O]/[CO 2 ] ~ 45x). Another issue with calculating GWP is that, unlike other GHG, water vapor does not decay in the environment, so an average over some time period or some other measure consistent with "time dependent decay," ., above, must be used in lieu of the time dependent decay of artificial or excess CO 2 , molecules. Other factors complicating its calculation are the Earth's temperature distribution, and the differing land masses in the Northern and Southern hemispheres.