Which one of the following is not a third generation progestrogen used in combined oral contraceptive pills ?
**Core Concept**
The question is testing knowledge of third-generation progestogens used in combined oral contraceptive pills (COCs). Third-generation progestogens are a class of synthetic progestins that have a unique chemical structure and are known for their favorable pharmacokinetic profiles.
**Why the Correct Answer is Right**
Third-generation progestogens, such as desogestrel and norgestimate, are characterized by their high potency and long duration of action. They are metabolized to biologically inactive metabolites, which reduces the risk of hormonal side effects. This class of progestogens is designed to provide a more stable and predictable hormonal profile, making them a popular choice for COCs.
**Why Each Wrong Option is Incorrect**
**Option A:** Desogestrel is a third-generation progestogen used in COCs, so it is incorrect.
**Option C:** Norgestimate is also a third-generation progestogen used in COCs, so it is incorrect.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that third-generation progestogens are designed to provide a more stable and predictable hormonal profile, which reduces the risk of hormonal side effects. However, they can still cause changes in lipid profiles, particularly an increase in HDL cholesterol.
**Correct Answer: D.**