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Tenex (guanfacine) and Alcohol / Food Interactions

There is 1 alcohol/food/lifestyle interaction with Tenex (guanfacine):


guanFACINE ↔ food

Major Food Interaction

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of guanfacine. The risk of adverse reactions such as hypotension, bradycardia, and sedation may increase. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Ketoconazole, a potent CYP450 3A4 inhibitor, has been reported to increase guanfacine peak plasma concentration (Cmax) and systemic exposure (AUC) by approximately 2- and 3-fold, respectively. A computer simulation suggests that fluconazole, a moderate CYP450 3A4 inhibitor, would increase guanfacine Cmax and AUC by about 1.5- and 2-fold, respectively. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition.

GENERALLY AVOID: Alcohol may enhance the sedative and hypotensive effects of guanfacine.

GENERALLY AVOID: Administration of extended-release guanfacine with a high-fat meal may increase the bioavailability of guanfacine. When a single 4 mg dose of extended-release guanfacine was administered to adult volunteers with a high-fat breakfast, mean guanfacine peak plasma concentration (Cmax) and systemic exposure (AUC) increased by approximately 75% and 40%, respectively, compared to dosing in a fasted state.

MANAGEMENT: Patients treated with guanfacine should avoid consumption of grapefruit and grapefruit juice. In addition, it is preferable to avoid or limit the use of alcohol during treatment. Patients should be advised against driving or operating hazardous machinery until they know how the medication affects them. The extended-release formulation of guanfacine should not be taken together with a high-fat meal.


  1. "Product Information. Tenex (guanfacine)." Wyeth-Ayerst Laboratories, Philadelphia, PA.
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0
  3. "Product Information. Intuniv (guanfacine)." Shire US Inc, Florence, KY.

Tenex (guanfacine) drug Interactions

There are 453 drug interactions with Tenex (guanfacine)

Tenex (guanfacine) disease Interactions

There are 5 disease interactions with Tenex (guanfacine) which include:

Drug Interaction Classification

The classifications below are a general guideline only. It is difficult to determine the relevance of a particular drug interaction to any individual given the large number of variables.

Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.

Do not stop taking any medications without consulting your healthcare provider.

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