Pentoxifylline (drug interactions)
Pentoxifylline is a medication primarily used to enhance blood circulation and reduce the "stickiness" of blood, making it beneficial for conditions like intermittent claudication. However, it is important to be aware of potential drug interactions that could increase the risk of excessive bleeding or other complications. Several herbal supplements and medications may pose risks when combined with pentoxifylline. For instance, chondroitin, garlic, ginkgo, and reishi are known to have blood-thinning properties, which can amplify the effects of pentoxifylline and should only be used together under medical supervision. Other substances like policosanol and white willow may also interfere with blood clotting, necessitating caution. Additionally, prescription medications such as antihypertensive and antidiabetic agents, xanthine derivatives, and certain antibiotics may lead to adverse effects when taken with pentoxifylline. Given the broad range of potential interactions, it is crucial for patients to consult their healthcare provider before combining pentoxifylline with any other medications or supplements.
Pentoxifylline (drug interactions)
- DEFINITION: A drug that makes the blood less “sticky” and is used to increase blood circulation.
- INTERACTIONS: Chondroitin, garlic, ginkgo, ginger, PC-SPES, policosanol, reishi, vinpocetine, white willow, vitamin E, various prescription medications
- TRADE NAME: Generic versions available
Chondroitin
Effect: Possible Harmful Interaction
Based on chondroitin’s chemical similarity to the anticoagulant drug heparin, it has been suggested that chondroitin might also have anticoagulant effects. There are no case reports of any problems relating to this, and studies indicate that chondroitin has, at most, a mild anticoagulant effect. Nonetheless, chondroitin should not be combined with pentoxifylline except under physician supervision.
Garlic, Ginkgo
Effect: Possible Harmful Interaction
The herb garlic (Allium sativum) is taken to lower cholesterol, among many other proposed uses. One of the possible side effects of garlic is an increased tendency to bleed. Therefore, one should not combine garlic and pentoxifylline except under medical supervision. The herb ginkgo (Ginkgo biloba) has been used to treat Alzheimer’s disease and ordinary age-related memory loss, among many other uses. Ginkgo appears to reduce the ability of platelets (blood-clotting cells) to stick together. Several case reports suggest that this blood-thinning effect of ginkgo may be associated with an increased risk of serious abnormal bleeding episodes in persons taking the herb. Because of these risks, one should not combine ginkgo and pentoxifylline without physician supervision.
PC-SPES
Effect: Possible Harmful Interaction
PC-SPES is an herbal combination that once showed promise for the treatment of prostate cancer. One case report suggests that PC-SPES might increase the risk of bleeding complications if combined with blood-thinning medications. Subsequent evidence has indicated that PC-SPES contains the strong prescription blood-thinner warfarin (Coumadin), making this interaction inevitable.
Policosanol
Effect: Possible Harmful Interaction
Policosanol is a supplement used to reduce cholesterol levels. It also interferes with platelet clumping, creating a risk of interactions with blood-thinning drugs.
For example, a thirty-day, double-blind, placebo-controlled trial of twenty-seven persons with high cholesterol levels found that policosanol at 10 milligrams (mg) daily markedly reduced the ability of blood platelets to clump together. Another double-blind placebo-controlled study of thirty-seven healthy volunteers found evidence that the blood-thinning effect of policosanol increased as the dose was increased: the larger the policosanol dose, the greater the effect. However, another double-blind placebo-controlled study of forty-three healthy volunteers compared the effects of policosanol (20 mg daily), the blood-thinner aspirin (100 mg daily), and policosanol and aspirin combined at these same doses. The results again showed that policosanol substantially reduced the ability of blood platelets to stick together, and that the combined therapy exhibited additive effects. Based on these findings, one should not combine pentoxifylline and policosanol except under medical supervision.
Reishi
Effect: Possible Harmful Interaction
One study suggests that reishi impairs platelet clumping. This creates the potential for an interaction with any blood-thinning medication.
Vinpocetine
Effect: Possible Harmful Interaction
The substance vinpocetine is sold as a dietary supplement for the treatment of age-related memory loss and impaired mental function. Vinpocetine is thought to inhibit blood platelets from forming clots. For this reason, it should not be combined with medications or natural substances that impair the blood’s ability to clot normally, as this may lead to excessive bleeding. One study found only a minimal interaction between the blood-thinning drug warfarin (Coumadin) and vinpocetine, so one should use caution.
White Willow
Effect: Possible Harmful Interaction
The herb white willow (Salix alba), also known as willow bark, is used to treat pain and fever. White willow contains a substance that is converted by the body into a salicylate similar to the blood thinner aspirin. For this reason, white willow might add to the effects of pentoxifylline, possibly thinning the blood too much. It may be advisable to avoid white willow while taking pentoxifylline, except under medical supervision.
Additional Herbs and Supplements
Effect: Possible Harmful Interaction
Herbs and supplements that impair the blood’s ability to coagulate (clot) might add to the effects of pentoxifylline, possibly increasing the risk of excessive bleeding. This includes, most prominently, vitamin E.
Numerous other substances could conceivably present this risk, including mesoglycan, bromelain (from the fruit and stem of the pineapple, Ananas comosus), chamomile (Matricaria recutita), Coleus forskohlii, danshen (Salvia miltorrhiza), dong quai (Angelica sinensis), feverfew (Tanacetum parthenium), fish oil, ginger (Zingiber officinale), horse chestnut (Aesculus hippocastanum), OPC’s (oligomeric proanthocyanidins), papaya (Carica papaya), and red clover (Trifolium pratense). Ginger may also have blood-thinning properties and could possibly interfere with pentoxifylline.
Other Interactions
Several other medications should be used with caution when taking pentoxifylline. Caution is advised when combining pentoxifylline with antihypertensive and antidiabetic agents, such as glibenclamide and metformin. Caution should also be used when taking xanthine derivatives, as excess central nervous stimulation could occur. Patients with renal, hepatic, and cardiovascular dysfunction and patients with retinal or cerebral hemorrhage should not take pentoxifylline. Medications for breathing problems such as asthma and Chronic Obstructive Pulmonary Disease can increase the adverse side effects of pentoxifylline, as can medications for stomach ulcers and heartburn. Certain antibiotics and antidepressants should also be avoided. Hundreds of medications exist that could cause interactions with pentoxifylline, some major and others minor, so patients should discuss all medications and supplements with their healthcare provider.
Bibliography
"Pentoxifylline." Drugs.com, 3 Aug. 2023, www.drugs.com/mtm/pentoxifylline.html. Accessed 22 Sept. 2024.
"Pentoxifylline Disease Interactions." Drugs.com, www.drugs.com/disease-interactions/pentoxifylline.html. Accessed 22 Sept. 2024.
"Pentoxifylline (Oral Route) Side Effects." Mayo Clinic, 1 Feb. 2024, www.mayoclinic.org/drugs-supplements/pentoxifylline-oral-route/side-effects/drg-20065425?p=1. Accessed 22 Sept. 2024.
"Pentoxifylline - StatPearls." NCBI, 29 Feb. 2024, www.ncbi.nlm.nih.gov/books/NBK559096. Accessed 22 Sept. 2024.
Rosenblatt, M., and J. Mindel. "Spontaneous Hyphema Associated with Ingestion of Ginkgo biloba Extract." New England Journal of Medicine, vol. 336, 1997, p. 1108.
Rowin, J., and S. L. Lewis. "Spontaneous Bilateral Subdural Hematomas with Chronic Ginkgo biloba Ingestion." Neurology, vol. 46, 1996, pp. 1775-1776.
Vale, S. "Subarachnoid Hemorrhage Associated with Ginkgo biloba." The Lancet, vol. 35, 1998, p. 36.
Weinrobe, M. C., and B. Montgomery. "Acquired Bleeding Diathesis in a Patient Taking PC-SPES." New England Journal of Medicine, vol. 345, 2001, pp. 1213-1214.