Alfuzosin Administration with Food and Drug Interactions
Alfuzosin extended-release must be taken immediately following a meal because food increases its bioavailability by 50%, and fasting conditions result in significantly reduced absorption that compromises therapeutic efficacy. 1
Food Requirements for Alfuzosin
The FDA label explicitly states that alfuzosin exhibits 50% lower absorption under fasting conditions, making administration with food mandatory for proper therapeutic effect. 1
The absolute bioavailability of alfuzosin 10 mg tablets under fed conditions is 49%, compared to substantially reduced absorption when taken on an empty stomach. 1
Alfuzosin should be taken immediately following a meal—not just with food, but specifically after eating—to ensure optimal drug exposure. 1
This food requirement is clinically important and distinguishes alfuzosin from other alpha-blockers; extended-release formulations of alfuzosin, doxazosin, tamsulosin, and silodosin are all food-sensitive, but alfuzosin has the most pronounced effect. 2
Contraindicated Drug Combinations
Alfuzosin is absolutely contraindicated with potent CYP3A4 inhibitors because these drugs increase alfuzosin exposure by 2-3 fold, creating dangerous cardiovascular risks. 1
Specific Contraindications
Ketoconazole (400 mg/day) increases alfuzosin Cmax by 2.3-fold and AUC by 3.2-fold; even lower doses (200 mg/day) increase Cmax by 2.1-fold and AUC by 2.5-fold. 1
The following drugs are explicitly contraindicated per the EASL hepatitis C guidelines when used with ritonavir-boosted regimens (which applies to alfuzosin): ketoconazole, itraconazole, ritonavir, and other potent CYP3A4 inhibitors. 3
Alfuzosin is specifically listed as contraindicated with ritonavir due to markedly increased plasma concentrations that would lead to serious adverse cardiovascular events including hypotension and syncope. 3
Moderate CYP3A4 Inhibitors Requiring Caution
Diltiazem, a moderate CYP3A4 inhibitor, increases alfuzosin Cmax by 1.5-fold and AUC by 1.3-fold, which may require dose adjustment or enhanced monitoring. 1
Although the FDA label notes that no blood pressure changes were observed in diltiazem interaction studies, diltiazem is an antihypertensive medication and the combination has potential to cause hypotension in some patients. 1
Other moderate CYP3A4 inhibitors (cimetidine, atenolol) can significantly elevate serum alfuzosin concentrations and enhance pharmacodynamic effects. 4
Grapefruit Juice and Citrus Interactions
Grapefruit juice is a selective intestinal CYP3A4 inhibitor that can increase drug exposure by more than fivefold, and alfuzosin should not be taken with grapefruit juice or citrus fruits. 2, 5
This interaction may intensify adverse cardiovascular effects of alfuzosin including dizziness, hypotension, and syncope. 2
Alcohol Interactions
- Alpha-1 adrenergic receptor antagonists including alfuzosin interact with alcohol, leading to orthostatic hypotension, and patients should be counseled to avoid or limit alcohol consumption. 2
Administration with Other Oral Medications
Alfuzosin can generally be taken with other oral medications, as there are no specific contraindications for concurrent administration with most drugs beyond the CYP3A4 inhibitors noted above. 1
The primary concern is timing with food rather than separation from other medications—alfuzosin must be taken immediately after a meal regardless of other medication schedules. 1
For patients on multiple medications, alfuzosin should be incorporated into the post-meal medication routine rather than requiring separate timing. 6
Special Population Considerations
In patients with moderate or severe hepatic impairment (Child-Pugh B and C), alfuzosin clearance is reduced to one-third to one-fourth of normal, resulting in 3-4 fold higher plasma concentrations, making it absolutely contraindicated in these patients. 1
Renal impairment increases alfuzosin Cmax and AUC by approximately 50% in patients with mild, moderate, or severe renal dysfunction, though no formal dose adjustment is required—enhanced monitoring is prudent. 1
Elderly patients ≥75 years have trough concentrations approximately 35% greater than those below 65 years, increasing risk of adverse effects. 1
Critical Pitfalls to Avoid
Never allow patients to take alfuzosin on an empty stomach or between meals, as this reduces bioavailability by 50% and leads to treatment failure. 1
Do not prescribe alfuzosin to patients taking potent CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir) as this combination is absolutely contraindicated. 3, 1
Counsel patients explicitly to avoid grapefruit juice and limit alcohol consumption while on alfuzosin therapy. 2
In patients with moderate-to-severe hepatic impairment, alfuzosin is contraindicated—do not attempt dose reduction, choose an alternative agent. 1
When combining alfuzosin with moderate CYP3A4 inhibitors like diltiazem, monitor closely for hypotension, dizziness, and syncope. 1