Phenobarbital (drug interactions)
Phenobarbital is a medication primarily used to control seizures, but it has notable interactions with various supplements and other drugs that can affect its efficacy and safety. Certain dietary supplements, such as folate and vitamin D, may be beneficial for individuals on phenobarbital due to its effects on nutrient absorption and metabolism. For instance, phenobarbital can lower folate levels, potentially leading to anemia, so supplementation is advisable, especially for women who are pregnant or planning to conceive.
Conversely, some herbal supplements like St. John's Wort and dong quai can heighten the risks of sun sensitivity when taken with phenobarbital, while ginkgo biloba poses a theoretical risk due to potential contaminants in its formulations, which could interfere with the medication's effectiveness. Additionally, combining phenobarbital with other sedative herbs, such as kava or valerian, can amplify sedation and pose serious health risks.
It is crucial for individuals taking phenobarbital to consult healthcare providers before combining it with any supplements or other medications, as there are significant interactions that can lead to diminished effectiveness or increased side effects. These considerations highlight the importance of careful management and supervision when using phenobarbital in conjunction with other substances.
Phenobarbital (drug interactions)
DEFINITION: Medications used to control seizures.
INTERACTIONS: Biotin, dong quai, folate, ginkgo biloba, glutamine, hops, kava, passionflower, St. John’s wort, valerian, vitamin D, vitamin K, various prescription medications
TRADE NAMES: Bellatal, Solfoton
RELATED DRUGS: Mebaral, mephobarbital, methylphenobarbital
Folate
Effect: Supplementation Possibly Helpful
Phenobarbital can reduce folate levels by increasing the vitamin breakdown rate. Over time, such a decrease can cause anemia. Taking folate supplements can correct this anemia. Anticonvulsant-induced folate deficiency might also cause congenital disabilities. Women who plan to become pregnant while on phenobarbital should be sure to take a supplement to prevent congenital disabilities.
Vitamin D
Effect: Supplementation Possibly Helpful
Phenobarbital appears to interfere with the normal absorption or metabolism of vitamin D. In turn, this can impair calcium absorption. Getting enough vitamin D (and calcium) should help prevent problems from developing.
Vitamin K
Effect: Supplementation Helpful for Pregnant Women
Children born to women taking phenobarbital 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; however, physician supervision is recommended.
Biotin
Effect: Supplementation Possibly Helpful, but Take at a Different Time of Day
Many antiseizure medications, including phenobarbital, are believed to interfere with the absorption of biotin. For this reason, persons taking phenobarbital 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.
Dong Quai, St. John’s Wort
Effect: Possible Harmful Interaction
Phenobarbital 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 use sunscreen or wear 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 possible harmful interaction involves potential contaminants in ginkgo, not ginkgo itself.
One study found that a natural nerve toxin 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 phenobarbital, unless advised by a physician.
Glutamine
Effect: Theoretical Harmful Interaction
Because phenobarbital works (at least in part) by blocking glutamate pathways in the brain, high dosages of glutamine might overwhelm the drug and increase the risk of seizures.
Other Interactions
Several other serious interactions exist between phenobarbital and other medications. Taking phenobarbital with central nervous system depressants can increase the sedative effects of both medications to dangerous levels, leading to serious respiratory depression. As phenobarbital can interfere with oral contraceptives, women who do not wish to become pregnant should use a backup method of birth control. Finally, phenobarbital can decrease the effectiveness of certain antibiotics, anticoagulants, and corticosteroids.
Bibliography
Arenz, A., et al. "Occurrence of Neurotoxic 4'-O-Methylpyridoxine in Ginkgo biloba Leaves, Ginkgo Medications, and Japanese Ginkgo Food." Planta Medica, vol. 62, 1996, pp. 548-551.
Cornelissen, M., et al. "Supplementation of Vitamin K in Pregnant Women Receiving Anticonvulsant Therapy Prevents Neonatal Vitamin K Deficiency." American Journal of Obstetrics and Gynecology, vol. 168, 1993, pp. 884-888.
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.
Lewis, Cassaundra B. "Phenobarbital - StatPearls." NCBI, 28 Feb. 2024, www.ncbi.nlm.nih.gov/books/NBK532277. Accessed 11 Sept. 2024.
Lewis, D. P., et al. "Drug and Environmental Factors Associated with Adverse Pregnancy Outcomes: Part I–Antiepileptic Drugs, Contraceptives, Smoking, and Folate." Annals of Pharmacotherapy, vol. 32, 1998, pp. 802-817.
"Phenobarbital." MedlinePlus 15 May 2020, medlineplus.gov/druginfo/meds/a682007.html. Accessed 11 Sept. 2024.
"Phenobarbital: Uses, Interactions & Side Effects." Cleveland Clinic, my.clevelandclinic.org/health/drugs/18614-phenobarbital-tablets. Accessed 11 Sept. 2024.