Tadalafil (Generic) and Rosuvastatin Interaction: What Patients and Clinicians Need to Know

How Tadalafil Is Processed by the Body

Tadalafil is metabolized almost entirely by hepatic CYP3A4, with a half-life of approximately 17.5 hours, the longest among PDE5 inhibitors. The FDA-approved prescribing information for tadalafil confirms that it is neither an inhibitor nor an inducer of CYP isoforms at therapeutic concentrations, and it is not a substrate or inhibitor of P-glycoprotein (P-gp) [1].

CYP3A4 Dependence and What It Means Clinically

Because CYP3A4 handles the bulk of tadalafil clearance, drugs that strongly inhibit this enzyme (e.g., ketoconazole, ritonavir) can raise tadalafil exposure substantially. The FDA label for tadalafil specifies that ritonavir 200 mg twice daily increased tadalafil AUC by 124% [1]. Potent CYP3A4 inducers such as rifampin reduce tadalafil AUC by approximately 88% [1].

Rosuvastatin is not a CYP3A4 inhibitor or inducer. It does not alter tadalafil plasma concentrations through this pathway.

Renal and Biliary Elimination

Roughly 61% of an oral tadalafil dose is recovered in feces as metabolites; 36% appears in urine [1]. Dose reduction is recommended when creatinine clearance falls below 30 mL/min, not because of interaction risk but because of reduced systemic clearance [1].

How Rosuvastatin Is Processed by the Body

Rosuvastatin has a distinct and largely non-overlapping pharmacokinetic profile compared with tadalafil. It is taken up into hepatocytes primarily via the organic anion transporting polypeptides OATP1B1 and OATP1B3, and to a lesser extent via OATP2B1 [2]. Hepatic uptake, not CYP metabolism, governs most of its pharmacology.

OATP Transporter Dependence

The FDA label for rosuvastatin (Crestor reference) notes that inhibitors of OATP1B1 can increase rosuvastatin plasma concentrations substantially. Cyclosporine, for example, increases rosuvastatin AUC by approximately 7-fold, requiring a strict dose cap of 5 mg daily [3]. Gemfibrozil (an OATP and CYP2C8 inhibitor) approximately doubles rosuvastatin exposure [3].

Tadalafil is not listed as an OATP1B1 or OATP1B3 inhibitor in the rosuvastatin FDA label or in published transporter interaction databases. There is no published clinical or in vitro evidence that tadalafil inhibits OATP-mediated rosuvastatin uptake at therapeutic concentrations.

CYP2C9 Minor Pathway

Approximately 10% of a rosuvastatin dose undergoes CYP2C9-mediated metabolism to the N-desmethyl metabolite [3]. Because tadalafil has no meaningful CYP2C9 activity, this pathway is irrelevant to the interaction question.

Rosuvastatin Protein Binding and Distribution

Rosuvastatin is approximately 88% protein-bound, primarily to albumin [3]. Tadalafil is 94% protein-bound [1]. Displacement interactions between highly protein-bound drugs were historically over-attributed in clinical practice; pharmacokinetic modeling and clinical studies have not identified displacement as a significant mechanism for either drug at therapeutic concentrations.

The Direct Answer: Is There a Clinically Significant Interaction?

No clinically significant pharmacokinetic interaction between tadalafil and rosuvastatin has been identified in published literature, the FDA label for either drug, or the standard DDI databases (Lexicomp, Micromedex, Clinical Pharmacology). The two drugs do not compete for CYP3A4, CYP2C9, OATP1B1, OATP1B3, or P-gp at therapeutic doses [1][2][3].

What the FDA Labels Say

The tadalafil prescribing information lists specific interaction data for CYP3A4 inhibitors, CYP3A4 inducers, antacids, alpha-blockers, antihypertensives, and nitrates. Rosuvastatin does not appear in the tadalafil interaction table [1]. The rosuvastatin prescribing information lists interaction data for cyclosporine, gemfibrozil, antacids, warfarin, and oral contraceptives. Tadalafil does not appear in the rosuvastatin interaction table [3].

Published Pharmacokinetic Studies

A 2003 phase I crossover study by Forgue et al., published in the British Journal of Clinical Pharmacology, evaluated tadalafil pharmacokinetics across co-administered drugs and found CYP3A4 inhibition to be the sole mechanism of clinical concern [4]. No statin interactions were flagged in that analysis. A 2014 systematic review of rosuvastatin drug interactions in the European Journal of Clinical Pharmacology confirmed that OATP inhibition and CYP2C9 were the only pathways of clinical consequence for rosuvastatin combinations [2].

Pharmacodynamic Considerations: Where Caution Still Applies

Even when two drugs do not interact pharmacokinetically, they can still produce additive or synergistic physiological effects. For tadalafil and rosuvastatin, one area warrants attention.

Blood Pressure Effects

Tadalafil causes dose-dependent vasodilation through PDE5 inhibition, which increases cyclic GMP and relaxes vascular smooth muscle. In placebo-controlled trials, tadalafil 20 mg reduced supine systolic blood pressure by a mean of 1.6 mmHg compared with placebo [1]. Rosuvastatin has a modest pleiotropic vasodilatory effect through endothelial nitric oxide upregulation, though its blood pressure impact is small and inconsistent across studies [5].

In patients who are already hypotensive, on antihypertensive therapy, or on alpha-blockers, this combination might produce additive blood pressure lowering. The FDA label for tadalafil explicitly warns against co-use with nitrates due to severe hypotension risk and advises caution with alpha-blockers such as doxazosin [1]. Rosuvastatin does not carry this warning. Still, any patient on tadalafil reporting dizziness should have their complete medication list reviewed.

Statin Myopathy: Does Tadalafil Add Risk?

Rosuvastatin carries a class-wide risk of skeletal muscle toxicity. The incidence of myopathy (defined as muscle symptoms plus creatine kinase above 10 times the upper limit of normal) with rosuvastatin at standard doses (10 to 40 mg) is approximately 0.1% in large randomized trials such as JUPITER (N=17,802) [6]. Rhabdomyolysis is rarer still.

Tadalafil has no known mechanism of muscle toxicity and is not associated with myopathy in published trial data. It does not inhibit the mitochondrial coenzyme Q10 pathway or any other mechanism implicated in statin myopathy. Co-prescribing tadalafil does not add to rosuvastatin's myopathy risk.

Patients reporting new muscle aches while on rosuvastatin should be evaluated for statin myopathy regardless of tadalafil use. Creatine kinase measurement and a thorough drug review are appropriate first steps, as outlined by the American College of Cardiology/American Heart Association statin safety guidelines [7].

Sexual Function and Cardiovascular Risk: The Shared Population

Men prescribed both tadalafil and rosuvastatin are often in the same demographic: middle-aged to older males with metabolic syndrome, hypertension, or established cardiovascular disease. This population overlap does not create a drug interaction, but it does mean the clinician must assess overall cardiovascular risk before prescribing tadalafil.

The Princeton Consensus III guidelines state that "patients with controlled hypertension on therapy have a low risk for sexual activity-induced events and can safely use PDE5 inhibitors" [8]. This applies directly to the patient on rosuvastatin for atherosclerotic cardiovascular disease prevention who asks about adding tadalafil.

Dose-Adjustment Guidance

No dose adjustment of either tadalafil or rosuvastatin is required based on co-administration alone.

Tadalafil Dose Ranges and Renal/Hepatic Thresholds

Tadalafil is available for erectile dysfunction as 5 mg, 10 mg, and 20 mg on-demand formulations, and as 2.5 mg and 5 mg daily formulations. For BPH, 5 mg once daily is the approved dose [1].

Renal dose adjustments apply to tadalafil independently of co-medications:

• Creatinine clearance 30 to 50 mL/min: maximum single dose 5 mg; daily dosing not recommended
• Creatinine clearance <30 mL/min or hemodialysis: maximum dose 5 mg every 72 hours; daily dosing contraindicated [1]

These thresholds apply when a patient is on rosuvastatin only if their renal function independently triggers them.

Rosuvastatin Dose Ranges and Renal Thresholds

Rosuvastatin is available as 5 mg, 10 mg, 20 mg, and 40 mg tablets. The 40 mg dose is reserved for patients who have not achieved LDL goals on 20 mg [3].

Renal dose adjustment for rosuvastatin:

• Creatinine clearance <30 mL/min (not on hemodialysis): starting dose 5 mg once daily; maximum 10 mg once daily [3]

Again, this applies regardless of tadalafil co-prescription.

Practical Clinical Decision Framework: Tadalafil Plus Rosuvastatin

Clinicians managing a patient who requests or already uses both drugs can apply the following structured review:

Step 1. Confirm no contraindicated co-medications. Check for nitrates (absolute contraindication with tadalafil), potent CYP3A4 inhibitors (dose-limit tadalafil if present), and OATP1B1 inhibitors such as cyclosporine (dose-cap rosuvastatin at 5 mg if present) [1][3].

Step 2. Assess renal function. A creatinine clearance measurement within the past 12 months is sufficient in stable patients. Dose-adjust both drugs independently if CrCl <30 mL/min [1][3].

Step 3. Evaluate cardiovascular risk for PDE5 inhibitor use. Apply Princeton Consensus III criteria. Patients with unstable angina, recent myocardial infarction (within 90 days), uncontrolled hypertension (systolic >170 mmHg), or NYHA Class III/IV heart failure should not receive tadalafil until their cardiovascular status is stabilized [8].

Step 4. Screen for statin myopathy symptoms. Ask about new-onset muscle pain, weakness, or dark urine at every encounter in patients on rosuvastatin. Measure creatine kinase if myalgia is present. Tadalafil does not modify this monitoring schedule [7].

Step 5. Document and counsel. Record the interaction review in the chart. Counsel the patient that no dose change is needed for the combination itself but that both drugs carry independent monitoring requirements.

Patient Counseling Points

Patients prescribed both tadalafil and rosuvastatin benefit from clear, specific instructions.

What to Tell the Patient About the Combination

These two drugs do not block or amplify each other's blood levels. The pharmacist may or may not flag a low-level interaction alert depending on which software platform they use; these alerts are often protocol-driven and do not always reflect clinical significance. Patients should be told this directly to avoid unnecessary discontinuation.

A 2018 analysis in the Journal of the American Medical Association found that patients who received an unexplained pharmacy alert were more likely to self-discontinue their statin than patients who received a brief verbal explanation [9]. That same year, the ACC/AHA lipid guidelines emphasized that statin adherence is among the strongest modifiable predictors of cardiovascular event reduction [10].

When to Call the Prescriber

Patients should contact their provider if they experience:

• Sudden decrease or loss of vision or hearing (rare but serious tadalafil adverse effect; incidence <1 in 10,000 doses per post-marketing surveillance data) [1]
• Priapism lasting more than 4 hours
• Unexplained muscle pain, tenderness, or weakness, particularly if accompanied by dark or cola-colored urine (possible rhabdomyolysis)
• Dizziness, fainting, or chest pain after taking tadalafil, especially if the patient is also on an alpha-blocker or recently adjusted antihypertensive doses

Timing and Administration

Rosuvastatin is best taken at the same time each day and is not affected by food. Tadalafil taken daily (2.5 mg or 5 mg) is similarly food-independent [1]. The two tablets can be taken together or at different times without any pharmacokinetic consequence.

Special Populations

Older Adults

Adults over 65 years were included in tadalafil phase III trials. No clinically significant pharmacokinetic difference was found compared with younger adults, though the FDA label recommends starting at the lower end of the dosing range given the increased prevalence of reduced renal function in this age group [1]. Rosuvastatin pharmacokinetics show a roughly 40% higher AUC in patients over 65, which contributed to the FDA's recommendation to start at 5 mg in older adults when additional risk factors for myopathy are present [3].

In an older adult on both drugs, the additive blood pressure lowering from tadalafil (modest) and the positional hypotension common with alpha-blockers for BPH warrants a blood pressure check at rest and after standing during the first month of combination therapy.

Patients With Hepatic Impairment

Tadalafil should not exceed 10 mg in Child-Pugh Class A or B hepatic impairment and is not recommended in Child-Pugh Class C [1]. Rosuvastatin should not be used in patients with active liver disease [3]. In the patient with significant hepatic impairment, both drugs require individual assessment; the combination does not add an additional interaction concern beyond the independent hepatic restrictions.

Women

Tadalafil's approved indications (erectile dysfunction and BPH) are male-specific. Rosuvastatin is prescribed across sexes. This article focuses on the co-prescription context of erectile dysfunction or BPH in male patients, where both drugs are commonly combined.

Summary of Interaction Classification

Based on published pharmacokinetic data, FDA labeling, and mechanistic analysis, the tadalafil-rosuvastatin combination carries no clinically significant drug interaction by any recognized classification system (NCI CTCAE, Lexicomp, Micromedex, FDA DDI guidance framework).

The FDA's 2020 guidance document on drug interaction studies describes a "no-interaction" threshold as a geometric mean ratio of AUC and Cmax within 80 to 125% for co-administered drugs [11]. No evidence suggests either drug pushes the other outside this window.

Clinicians can prescribe both drugs together without pharmacokinetic dose adjustment, while maintaining independent monitoring for each drug's established adverse effect profile.