Primidone (drug interactions)
Primidone is a medication primarily used to control epileptic seizures, similar to phenobarbital. However, it can interact with various substances, including supplements and herbal remedies, which may affect its efficacy and safety. Notably, primidone can decrease folate levels, potentially leading to anemia and posing risks for pregnant women, who are advised to supplement with folate. It also appears to interfere with the metabolism of vitamins D and K, which can lead to complications such as calcium absorption issues and bleeding disorders in newborns.
Additionally, certain herbs like St. John's wort, dong quai, and kava may exacerbate the sun sensitivity associated with primidone, increasing the risk of skin reactions. Ginkgo biloba poses a theoretical risk due to potential contaminants that could negatively impact seizure control. Primidone may also reduce the effectiveness of hormonal birth control and anticoagulants like warfarin, necessitating careful management and consultation with healthcare providers. Overall, individuals taking primidone should be mindful of these interactions and consider dietary and supplemental adjustments under medical guidance.
Primidone (drug interactions)
DEFINITION: Like phenobarbital, to which it is closely related, primidone is used to control epileptic seizures.
INTERACTIONS: Biotin, dong quai, folate, ginkgo biloba, glutamine, hops, kava, passionflower, St. John’s wort, valerian, vitamin B3, vitamin D, vitamin K, calcium, various prescription medications
TRADE NAME: Mysoline
Folate
Effect: Supplementation Possibly Helpful
Primidone can reduce folate levels by increasing the vitamin breakdown rate. Over time, such a decrease can cause anemia. Taking folate supplements will correct this anemia. Anticonvulsant-induced folate deficiency might also cause congenital disabilities. Women who plan to become pregnant while on primidone should be sure to take a supplement to prevent deficiency.
Vitamin D
Effect: Supplementation Possibly Helpful
Primidone appears to interfere with the normal absorption or metabolism of vitamin D. This, in turn, impairs calcium absorption, with many potential complications. To help avoid this problem, one should consume adequate amounts of vitamin D. Calcium supplementation may also be necessary.
Vitamin K
Effect: Supplementation Possibly Helpful for Pregnant Women
Children born to women taking primidone while pregnant may be deficient in vitamin K. This might lead to bleeding disorders and facial bone abnormalities. Supplementing with vitamin K during pregnancy should help. Physician supervision is also recommended.
Biotin
Effect: Supplementation Possibly Helpful, but Take at a Different Time of Day
Many antiseizure medications, including primidone, are believed to interfere with the absorption of biotin. For this reason, persons taking primidone may benefit from extra biotin. Biotin should be taken two to three hours apart from antiseizure medication. One should not exceed the recommended daily intake because too much biotin might interfere with the effectiveness of the medication.
Glutamine
Effect: Theoretical Harmful Interaction
Because many antiepileptic drugs, including primidone, work by blocking glutamate stimulation in the brain, high dosages of glutamine might counteract the drugs’ effects and pose a risk of increased seizures.
Vitamin B3
Effect: Potentially Dangerous Interaction
Niacinamide (a form of vitamin B3) might increase primidone blood levels, possibly requiring reduced drug dosage.
Dong Quai, St. John’s Wort
Effect: Possible Harmful Interaction
Primidone has been reported to cause increased sensitivity to the sun, amplifying the risk of sunburn or skin rash. Because St. John’s wort and dong quai may also cause this problem, taking them during treatment with this drug might add to this risk. One should wear sunscreen or protective clothing during sun exposure if taking one of these herbs while using this anticonvulsant.
Ginkgo biloba
Effect: Possible Harmful Interaction
The herb ginkgo (Ginkgo biloba) has been used to treat Alzheimer’s disease and age-related memory loss, among many other conditions. The interaction with primidone involves potential contaminants in ginkgo, not ginkgo itself.
One study found that a natural nerve toxin present in the seeds of Ginkgo biloba made its way into standardized ginkgo extracts prepared from the leaves. This toxin has been associated with convulsions and death in laboratory animals.
The detected amounts of this toxic substance are considered harmless. However, given the lack of satisfactory standardization of herbal formulations in the United States, some batches of product might contain higher contents of the toxin, depending on the season of harvest. In light of these findings, taking a ginkgo product that happened to contain significant levels of the nerve toxin might theoretically prevent an anticonvulsant from working as well as expected.
Hops, Kava, Passionflower, Valerian
Effect: Possible Harmful Interaction
The herb kava (Piper methysticum) has a sedative effect and is used for anxiety and insomnia. Combining kava with anticonvulsants, which possess similar depressant effects, could result in add-on or excessive physical depression, sedation, and impairment. Because of the potentially serious consequences, one should avoid combining these herbs with anticonvulsants or other drugs that also have sedative or depressant effects, such as primidone, unless advised by a physician.
Other Considerations
Primidone may reduce the effectiveness of hormonal birth control. Taking primidone with anticonvulsant drugs or central nervous system depressants can increase the risk of side effects such as drowsiness and cognitive impairment. Primidone can decrease the anticoagulation effects of warfarin and increase the risk of blood clots. Taking primidone and corticosteroids may reduce their effectiveness. Additionally, the risk of serious side effects increases significantly with the use of illicit drugs or alcohol.
Bibliography
Kishi, T., et al. "Mechanism for Reduction of Serum Folate by Antiepileptic Drugs During Prolonged Therapy." Journal of the Neurological Sciences, vol. 145, 1997, pp. 109-112.
Kupiec, T., and V. Raj. "Fatal Seizures Due to Potential Herb-Drug Interactions with Ginkgo biloba." Journal of Analytical Toxicology, vol. 29, 2006, pp. 755-758.
"Primidone." National Center for Biotechnology Information, 28 Feb. 2024, www.ncbi.nlm.nih.gov/books/NBK562297. Accessed 11 Sept. 2024.
"Primidone (Mysoline): Uses & Side Effects." Cleveland Clinic, my.clevelandclinic.org/health/drugs/20024-primidone-tablets. Accessed 11 Sept. 2024.
"Primidone (Oral Route) Precautions." Mayo Clinic, www.mayoclinic.org/drugs-supplements/primidone-oral-route/precautions/drg-20065638. Accessed 11 Sept. 2024.