Drug General Information (ID: DDIYNK2M48)
Drug Name			Levothyroxine		Drug Info		Orlistat		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antithyroid Agents				Antiobesity Agents
Structure

Mechanism of Levothyroxine-Orlistat Interaction (Severity Level: Moderate)
Altered Fat-soluble drugs absorption Click to Show/Hide Mechanism Graph
Drug Name		Levothyroxine				Orlistat
Mechanism		Fat-soluble agent				Decrease fat-soluble agent absorption
Key Mechanism Factor 1
		Factor Name		Pharmacokinetic
		Factor Description		Alters the absorption of the drug, leading to changes in the plasma concentration of the drug and affecting the pharmacological effects.
Mechanism Description		Decreased absorption of Levothyroxine caused by Orlistat

Recommended Action
Management		Orlistat and oral thyroid hormone preparations should be administered at least 4 hours apart. Close clinical and laboratory monitoring of thyroid function is recommended. Patients should be advised to contact their physician if they experience symptoms of hypothyroidism such as fatigue, muscle weakness or pain, joint stiffness, depression, constipation, hoarseness, weight gain, hair loss, brittle nails, pale or dry skin, cold intolerance, memory problems, confusion, or menstrual irregularities.

References
1	Filippatos TD, Derdemezis CS, Gazi IF, Nakou ES, Mikhailidis DP, Elisaf MS "Orlistat-associated adverse effects and drug interactions: a critical review." Drug Saf 31 (2008): 53-65. [PMID: 18095746]
2	Madhava K, Hartley A "Hypothyroidism in thyroid carcinama follow-up: orlistat may inhibit the absorption of thyroxine." Clin Oncol 17 (2005): 492. [PMID: 16149295]
3	Product Information. Synthroid (levothyroxine). Abbott Pharmaceutical, Abbott Park, IL.
4	Product Information. Xenical (orlistat). Roche Laboratories, Nutley, NJ.