guanfacine (Intuniv, Tenex) (cont.)

Pharmacy Author:
Medical and Pharmacy Editor:

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS:

  • Intuniv: Extended-Release Tablets: 1, 2, 3, and 4 mg
  • Tenex: Immediate-Release Tablets: 1 and 2 mg

STORAGE: Tablets should be stored at room temperature, between 15 C to 30 C (59 F to 86 F).

DOSING:

  • Extended release guanfacine for the treatment of ADHD: The recommended dose is 1 to 4 mg by mouth in the morning or evening. Patients are usually started on 1 mg once daily which is then increased in increments no larger than 1 mg/week as needed or tolerated. Tablets should not be administered with high-fat meals.
  • Immediate release guanfacine for the treatment of hypertension: The recommended dose is 1 mg usually at bedtime. The dose may be increased at 3 to 4 week intervals as necessary. The usual dose range is 0.5 to 2 mg once daily.

DRUG INTERACTIONS: Rifampin and St. John's wort may reduce blood levels of guanfacine by increasing its metabolism (breakdown) in the intestine; doses of guanfacine may need to be increased when combined with drugs that reduce its blood levels.

Other drugs that also may reduce blood levels of guanfacine include carbamazepine (Tegretol, Tegretol XR , Equetro, Carbatrol, Epitol, Teril), phenytoin (Dilantin, Dilantin-125), phenobarbital, oxcarbazepine (Trileptal), rifabutin, rifampin, rifapentine, bosentan (Tracleer), and tipranavir/ritonavir (Aptivus).

Ketoconazole (Nizoral, Extina, Xolegel, Kuric), itraconazole (Sporanox), and simeprevir (Olysio) may increase blood levels of guanfacine by decreasing its metabolism in the intestine; the dose of guanfacine may need to be decreased when combined with drugs that increase its blood levels.

Medically Reviewed by a Doctor on 9/11/2015


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