Efavirenz Tablets and Guanfacine ER
Determining the interaction of Efavirenz Tablets and Guanfacine ER and the possibility of their joint administration.
In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.
Consumer:Efavirenz may significantly reduce the blood levels of guanFACINE, which may make the medication less effective in treating your condition. Talk to your doctor if you have any questions or concerns. Your doctor may be able to prescribe alternatives that do not interact, or you may need a dose adjustment or more frequent monitoring to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.
Professional:ADJUST DOSE: Coadministration with inducers of CYP450 3A4 may significantly decrease the plasma concentrations of guanfacine, which is primarily metabolized by the isoenzyme. Rifampin, a potent CYP450 3A4 inducer, has been reported to decrease guanfacine peak plasma concentration (Cmax) and systemic exposure (AUC) by 54% and 70%, respectively. A computer simulation suggests that efavirenz, a moderate CYP450 3A4 inducer, would reduce guanfacine Cmax and AUC by a similar magnitude.
MANAGEMENT: Close monitoring and dosage adjustment should be considered when guanfacine is administered with potent and moderate CYP450 3A4 inducers. For extended-release guanfacine, some manufacturers recommend increasing the dosage up to double the recommended level when initiating therapy in patients who are already receiving a CYP450 3A4 inducer. Further dosage adjustments may be required based on patient tolerance and response. If a CYP450 3A4 inducer is added to existing guanfacine therapy, the guanfacine dosage may be increased up to double the recommended level over 1 to 2 weeks. The dosage should be decreased to the recommended level over 1 to 2 weeks following discontinuation of the CYP450 3A4 inducer.
- Kiechel JR, Lavene D, Guerret M, Comoy E, Godin M, Fillastre JP "Pharmacokinetic aspects of guanfacine withdrawal syndrome in a hypertensive patient with chronic renal failure." Eur J Clin Pharmacol 25 (1983): 463-6
- "Product Information. Intuniv (guanfacine)." Shire US Inc, Florence, KY.
- Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
Generic Name: efavirenz
Brand name: Sustiva
Synonyms: Efavirenz
Generic Name: guanfacine
Brand name: Intuniv, Tenex
Synonyms: Guanfacine, GuanFACINE
In the course of checking the drug compatibility and interactions, data from the following reference sources was used: Drugs.com, Rxlist.com, Webmd.com, Medscape.com.
- Efavirenz Tablets-Guanfacine Extended-Release Tablets
- Efavirenz Tablets-Guanfacine Tablets
- Efavirenz Tablets-Guanidine
- Efavirenz Tablets-Guar Gum
- Efavirenz Tablets-Guiadrine DX
- Efavirenz Tablets-Guiatex PE
- Guanfacine ER-Efavirenz, emtricitabine, and tenofovir
- Guanfacine ER-Efavirenz, Emtricitabine, and Tenofovir Disoproxil Fumarate
- Guanfacine ER-Efavirenz, lamivudine, and tenofovir
- Guanfacine ER-Efavirenz, Lamivudine, and Tenofovir Disoproxil Fumarate
- Guanfacine ER-Effaclor Duo
- Guanfacine ER-Effer-K