Drug General Information (ID: DDI1QUWA93)
Drug Name			Ranitidine (bismuth citrate)		Drug Info		Lapatinib		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antiulcer Agents				Antineoplastics
Structure

Mechanism of Ranitidine (bismuth citrate)-Lapatinib Interaction (Severity Level: Moderate)
Altered gastric pH Click to Show/Hide Mechanism Graph
Drug Name		Ranitidine (bismuth citrate)				Lapatinib
Mechanism		Gastric alkalinizer				Gastric pH sensitive
Key Mechanism Factor 1
		Factor Name		Gastric pH
		Factor Description		The normal pH range of gastric acid is between 1.5 and 3.5 and is highly acidic, consisting mainly of hydrochloric acid. Changes in the pH of the stomach can alter the absorption of drugs.
Mechanism Description		Decreased absorption of Lapatinib due to altered gastric pH caused by Ranitidine (bismuth citrate)

Recommended Action
Management		Caution may be advisable if lapatinib is used in combination with H2-receptor antagonists or proton pump inhibitors. Patients should be monitored for potentially reduced therapeutic response to lapatinib.

References
1	Cerner Multum, Inc. "UK Summary of Product Characteristics.".
2	Product Information. Tykerb (lapatinib). Novartis Pharmaceuticals, East Hanover, NJ.