Mercilon® is a birth control pill. There is an important drug which is a hormone. namely ethinylestradiol 0.020 mg and desogestrel 0.150 mg mixed together in the same tablet. Mersilon has both 21 tablets and 28 tablets. The 21 tablet type has the same amount of hormones in every tablet. The 28 tablet type has the same amount of hormones in 21 tablets (tablets 1-21) and another 7 tablets ( ...