Drug General Information (ID: DDI3TE4Q1C)
Drug Name			Mestranol		Drug Info		Omadacycline		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Estrogens				Tetracyclines
Structure

Mechanism of Mestranol-Omadacycline Interaction (Severity Level: Moderate)
Complex formation Click to Show/Hide Mechanism Graph
Drug Name		Mestranol				Omadacycline
Mechanism		Polyvalent cations				Binds to polyvalent cations
Key Mechanism Factor 1
		Factor Name		Chelation
		Factor Description		Chelation is a direct drug interaction that usually involves the formation of dimers or trimers, resulting in larger complexes and poorer absorption.
Mechanism Description		Decreased absorption of Mestranol due to formation of complexes caused by Omadacycline

Recommended Action
Management		Until further data are available, women using oral contraceptives should be advised of the risk of breakthrough bleeding and unintended pregnancy during concomitant antimicrobial therapy. In general, quinolone antibiotics should be dosed either 2 to 4 hours before or 4 to 6 hours after iron preparations to minimize the potential for interaction. The administration of tetracycline antibiotics and iron preparations should be separated by at least three to four hours, although this may not prevent the interaction with doxycycline. Concomitant use of doxycycline and iron preparations should be avoided if possible.

References
1	Friedman CI, Huneke AL, Kim MH, Powell J "The effect of ampicillin on oral contraceptive effectiveness." Obstet Gynecol 55 (1980): 33-7. [PMID: 7188714]
2	Kleier DJ, Tucker JE "Oral contraceptive failure secondary to dentally prescribed drugs: fact or fiction?" J Colo Dent Assoc 66 (1987): 5-6. [PMID: 3478352]
3	Silber TJ "Apparent oral contraceptive failure associated with antibiotic administration." J Adolesc Health Care 4 (1983): 287-9. [PMID: 6643209]