Drug General Information (ID: DDIRCDXEY8)
Drug Name			Warfarin		Drug Info		Sulfinpyrazone		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Anticoagulants				Uricosuric Agents
Structure

Mechanism of Warfarin-Sulfinpyrazone Interaction (Severity Level: Major)
Increased risk of bleeding Click to Show/Hide Mechanism Graph
Drug Name		Warfarin				Sulfinpyrazone
Mechanism		Risk of bleeding Anticoagulant				Risk of bleeding Antiplatelet effects
Key Mechanism Factor 1
		Factor Name		Bleeding
		Factor Description		Patients may be at risk for bleeding when the outcome of a disease or disease treatment confounds the standard mechanisms for maintaining hemostasis. Signs or symptoms of abnormal bleeding include: bleeding that takes a long time to stop (including nosebleeds, bleeding gums, bleeding from cuts and abrasions, and menstrual bleeding); severe unexplained bruising, or bruising that becomes larger; blood in the urine or stool, etc.
Mechanism Description		Increased risk of bleeding by the combination of Warfarin and Sulfinpyrazone

Recommended Action
Management		If coumarin derivatives must be used with sulfinpyrazone, the patient should be monitored for excessive anticoagulation. However, it is best to avoid this combination or reduce the anticoagulant dosage by 20% to 50%. Patients should be advised to notify their physician if they experience any signs of excessive anticoagulation, such as unusual or prolonged bleeding, bruising, vomiting, change in stool or urine color, headache, dizziness, or weakness.

References
1	Bailey RR, Reddy J "Potentiation of warfarin action by sulphinpyrazone." Lancet 1 (1980): 254. [PMID: 6101699]
2	Davis JW, Johns LE Jr "Possible interaction of sulfinpyrazone with coumarins." N Engl J Med 299 (1978): 955. [PMID: 692605]
3	Gallus A, Birkett D "Sulphinpyrazone and warfarin: a probable drug interaction." Lancet 1 (1980): 535-6. [PMID: 6102248]
4	Girolami A, Fabris F, Casonato A, Randi ML "Potentiation of anticoagulant response to warfarin by sulphinpyrazone: a double-blind study in patients with prosthetic heart valves." Clin Lab Haematol 4 (1982): 23-6. [PMID: 7067372]
5	Toon S, Low LK, Gibaldi M, et al. The warfarin-sulfinpyrazone interaction: stereochemical considerations. Clin Pharmacol Ther. 1986;39(1):15-24. [PMID: 3943265]
6	Mattingly D, Bradley M, Selley PJ "Hazards of sulphinpyrazone." Br Med J 2 (1978): 1786-7. [PMID: 310703]
7	Nenci GG, Agnelli G, Berrettini M "Biphasic sulphinpyrazone-warfarin interaction." Br Med J (Clin Res Ed) 282 (1981): 1361-2. [PMID: 6786498]
8	Nenci GG, Agnelli G, Berrettini M "Biphasic sulphinpyrazone-warfarin interaction." Br Med J 282 (1981): 1361-2. [PMID: 6786498]
9	Thompson PL, Serjeant C "Potentially serious interaction of warfarin with sulphinpyrazone." Med J Aust 1 (1981): 41. [PMID: 7207296]
10	Toon S, Low LK, Gibaldi M, et al "The warfarin-sulfinpyrazone interaction: stereochemical considerations." Clin Pharmacol Ther 39 (1986): 15-24. [PMID: 3943265]
11	Weiss M "Potentiation of coumarin effect by sulfinpyrazone." Lancet 1 (1979): 609. [PMID: 85191]
12	Wells PS, Holbrook AM, Crowther NR, Hirsh J "Interactions of warfarin with drugs and food." Ann Intern Med 121 (1994): 676-83. [PMID: 7944078]