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Drug Interactions between doxazosin and Prezcobix

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

doxazosin cobicistat

Applies to: doxazosin and Prezcobix (cobicistat / darunavir)

MONITOR: Coadministration with potent inhibitors of CYP450 3A4 may increase the plasma concentrations and effects of doxazosin. In vitro studies suggest that the primary pathway for elimination of doxazosin is via CYP450 3A4.

MANAGEMENT: Caution is advised if doxazosin is used concomitantly with potent CYP450 3A4 inhibitors. Blood pressure and pharmacologic response to doxazosin should be monitored closely whenever a potent CYP450 3A4 inhibitor is added to or withdrawn from therapy, and the doxazosin dosage adjusted if necessary. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, orthostasis, syncope, or tachycardia. Patients should also avoid driving or operating hazardous machinery until they know how the medication affects them.

References (3)
  1. (2001) "Product Information. Cardura (doxazosin)." Pfizer U.S. Pharmaceuticals
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink

Drug and food/lifestyle interactions

Moderate

darunavir food/lifestyle

Applies to: Prezcobix (cobicistat / darunavir)

ADJUST DOSING INTERVAL: Food enhances the absorption and oral bioavailability of darunavir administered in combination with low-dose ritonavir. The mechanism is unknown. When administered with food, the peak plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) of darunavir were approximately 30% higher than when administered in the fasting state. Darunavir exposure was similar for the range of meals studied. The total caloric content of the various meals evaluated ranged from 240 Kcal (12 grams fat) to 928 Kcal (56 grams fat).

MANAGEMENT: To ensure maximal oral absorption, darunavir coadministered with ritonavir should be taken with food. The type of food is not important.

References (1)
  1. (2006) "Product Information. Prezista (darunavir)." Ortho Biotech Inc
Moderate

doxazosin food/lifestyle

Applies to: doxazosin

GENERALLY AVOID: The concurrent use of ethanol and alpha-1 adrenergic blockers may cause increased hypotensive effects. Patients with aldehyde dehydrogenase deficiencies (primarily Asians) may be at a higher risk of this interaction. The mechanism has not been determined. Data exist for prazosin and other alpha adrenergic blockers are expected to interact also. In addition, any patients taking alpha adrenergic blockers may experience excessive orthostatic hypotension with ethanol ingestion, due to ethanol's unopposed vasodilatory effects in the presence of alpha adrenergic blockade.

MANAGEMENT: Patients who develop a flushing reaction after ethanol ingestion (indicates a possible aldehyde dehydrogenase deficiency) should be advised to avoid ethanol or limit their intake. All patients should be warned about the possibility of orthostatic hypotension with concurrent ethanol use.

References (2)
  1. Kawano Y, Abe H, Kojima S, Takishita S, Omae T (2000) "Interaction of alcohol and an a1-blocker on ambulatory blood pressure in patients with essential hypertension." Am J Hypertens, 13, p. 307-12
  2. (2002) "Product Information. Xatral (alfuzosin)." Sanofi-Synthelabo Canada Inc

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
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.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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