Drug General Information (ID: DDIVMCOD0N)
Drug Name			Cefdinir		Drug Info		Mestranol		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antibiotics				Estrogens
Structure

Mechanism of Cefdinir-Mestranol Interaction (Severity Level: Moderate)
Complex formation Click to Show/Hide Mechanism Graph
Drug Name		Cefdinir				Mestranol
Mechanism		Binds to polyvalent cations				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 Cefdinir

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. alternative or additional methods of birth control should be considered during and for at least one week beyond the last dose of short-term antimicrobial therapy, and for at least the initial weeks of long-term antimicrobial therapy when risk may be the greatest.To minimize potential interaction with iron, the product labeling recommends that cefdinir be taken at least 2 hours before or 2 hours after administration of iron-containing products.

References
1	Barnett ML "Inhibition of oral contraceptive effectiveness by concurrent antibiotic administration." J Periodontol 56 (1985): 18-20. [PMID: 3882930]
2	Dickinson BD, Altman RD, Nielsen NH, Sterling ML "Drug interactions between oral contraceptives and antibiotics." Obstet Gynecol 98(5 Pt 1) (2001): 853-60. [PMID: 11704183]
3	King VJ "OC failure rates and oral antibiotics." J Fam Pract 45 (1997): 104-5. [PMID: 9267366]