Drug General Information (ID: DDICS5ZQ7F)
Drug Name			Colesevelam		Drug Info		Dienogest		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Bile Acid Sequestrants				Contraceptives
Structure

Mechanism of Colesevelam-Dienogest Interaction (Severity Level: Moderate)
Complex formation Click to Show/Hide Mechanism Graph
Drug Name		Colesevelam				Dienogest
Mechanism		Anion exchange resin/polymer				Binds to anion exchange resin/polymer
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 Colesevelam due to formation of complexes caused by Dienogest

Recommended Action
Management		Oral contraceptives containing ethinyl estradiol and norethindrone should be administered at least 4 hours before the colesevelam dose. The same precaution may be applicable to other contraceptive hormones, although data are lacking.

References
1	Bailey DG, Arnold JMO, Spence JD "Grapefruit juice and drugs - how significant is the interaction." Clin Pharmacokinet 26 (1994): 91-8. [PMID: 8162660]
2	Gunston GD, Mehta U "Potentially serious drug interactions with grapefruit juice." S Afr Med J 90 (2000): 41. [PMID: 10721388]
3	Product Information. Welchol (colesevelam) Daiichi Sankyo, Inc., Parsippany, NJ.