Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
FINASTERIDE AND TADALAFIL vs ATMEKSI
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Finasteride is a 5α-reductase inhibitor that inhibits conversion of testosterone to dihydrotestosterone (DHT). Tadalafil is a phosphodiesterase-5 (PDE5) inhibitor that enhances nitric oxide-mediated vasodilation by increasing cyclic guanosine monophosphate (c GMP) in smooth muscle.
ATMEKSI (atazanavir/cobicistat) is a fixed-dose combination of atazanavir, an HIV-1 protease inhibitor that inhibits viral protease, preventing cleavage of viral polyproteins and resulting in immature non-infectious virions, and cobicistat, a pharmacokinetic enhancer that inhibits CYP3A, increasing atazanavir exposure.
Treatment of benign prostatic hyperplasia (BPH)
Treatment of HIV-1 infection in adults and pediatric patients weighing at least 35 kg,Off-label use as part of antiretroviral therapy in treatment-experienced patients with viral suppression
One capsule containing finasteride 5 mg and tadalafil 5 mg orally once daily.
1.5 mg/kg IV every 4 weeks
Finasteride: 6-8 hours (elderly ~8 hours); Tadalafil: 17.5 hours (enables once-daily dosing).
Terminal elimination half-life is 12 hours; renally impaired patients have prolonged half-life up to 24 hours.
Finasteride is extensively metabolized in the liver via CYP3A4; tadalafil is primarily metabolized by CYP3A4.
Atazanavir is metabolized by CYP3A4; cobicistat is metabolized by CYP3A and to a minor extent by CYP2D6.
Finasteride: 57% feces, 39% urine (metabolites); Tadalafil: 36% urine, 61% feces (mostly metabolites).
Primarily renal (80% unchanged) and biliary/fecal (15% as metabolites).
Finasteride: 90% bound to albumin and alpha-1-acid glycoprotein; Tadalafil: 94% bound to albumin.
95% bound to albumin and alpha-1-acid glycoprotein.
Finasteride: 76 L/kg (1.1 L/kg in elderly); Tadalafil: 63-77 L/kg (extensive tissue distribution).
2.0 L/kg, indicating extensive tissue distribution.
Finasteride: 63% oral (80% relative to IV); Tadalafil: 80% oral (bioavailability unaffected by food).
Oral: 60-70% due to first-pass metabolism.
No adjustment for mild-moderate renal impairment (Cr Cl ≥30 m L/min). Avoid in severe renal impairment (Cr Cl <30 m L/min) or on dialysis due to increased tadalafil exposure.
GFR 15-29 m L/min: 1.0 mg/kg IV every 4 weeks; GFR <15 m L/min: not recommended
Child-Pugh A: no adjustment. Child-Pugh B: limit tadalafil dose to 5 mg (same as given); use caution. Child-Pugh C: avoid use.
Child-Pugh A: no adjustment; Child-Pugh B: 1.0 mg/kg IV every 4 weeks; Child-Pugh C: not recommended
Not indicated in pediatric patients; safety and efficacy not established.
Age 2-17 years: 1.5 mg/kg IV every 4 weeks; maximum 120 mg per dose
No dose adjustment required; monitor for orthostatic hypotension and dizziness, as elderly may be more sensitive to vasodilatory effects.
No specific adjustment; monitor renal function and reduce dose if GFR <30 m L/min
There is no FDA black box warning for the combination product. Individual components have warnings: Finasteride exposure during pregnancy may cause abnormalities of male external genitalia; Tadalafil is contraindicated in patients taking guanylate cyclase stimulators (e.g., riociguat) and nitrates.
None
Risk of priapism (tadalafil); sudden hearing loss (tadalafil); orthostatic hypotension with concomitant antihypertensives; prostate-specific antigen (PSA) level reduction (finasteride); risk of high-grade prostate cancer (finasteride); use in women of childbearing potential (finasteride teratogenicity).
Hepatotoxicity, especially in patients with pre-existing liver disease or elevated transaminases,Nephrolithiasis and cholelithiasis,Cardiac conduction abnormalities (PR interval prolongation),Risk of developing resistance if not used with other antiretrovirals,Renal impairment (cobicistat decreases estimated creatinine clearance)
Hypersensitivity to finasteride or tadalafil; concurrent use of nitrates or guanylate cyclase stimulators (e.g., riociguat); women who are or may become pregnant (finasteride teratogenicity).
Concomitant use with drugs highly dependent on CYP3A for clearance (e.g., alfuzosin, rifampin, ergot derivatives, St. John's wort, lovastatin, simvastatin, sildenafil for pulmonary arterial hypertension),Severe hepatic impairment (Child-Pugh Class B or C)
Avoid grapefruit and grapefruit juice as they increase tadalafil plasma concentrations. Alcohol may potentiate hypotension and dizziness. High-fat meals may delay tadalafil absorption but do not reduce efficacy.
Avoid alcohol (may exacerbate CNS effects). Grapefruit juice may increase atomoxetine exposure; limit consumption. High-fat meals do not significantly affect absorption.
Finasteride: Contraindicated in pregnancy due to risk of hypospadias in male fetuses (Category X). Tadalafil: Category B; no fetal harm in animal studies, but insufficient human data. Avoid combination in pregnant women.
First trimester: Limited human data; animal studies show no teratogenicity at therapeutic doses. Second and third trimesters: No known fetal risks. Avoid use during organogenesis unless benefit outweighs risk.
Finasteride: Excreted in breast milk (M/P ratio unknown); not recommended. Tadalafil: Presence in breast milk unknown; avoid due to potential adverse effects.
Not recommended during breastfeeding. M/P ratio unknown. Excreted in animal milk; potential for serious adverse reactions in nursing infants.
Contraindicated in pregnancy; pharmacokinetic changes in pregnancy do not apply as use is not recommended. No dose adjustment applicable.
No dose adjustment required in pregnancy. Pharmacokinetic profile unchanged.
Finasteride and tadalafil combination is used for benign prostatic hyperplasia (BPH). Tadalafil may cause priapism; advise immediate medical attention for erections lasting >4 hours. Finasteride decreases serum PSA by ~50%; double PSA values for interpretation. Avoid coadministration with strong CYP3A4 inhibitors (e.g., ketoconazole) due to increased tadalafil exposure. Tadalafil is contraindicated with nitrates due to severe hypotension. Assess cardiovascular stability before prescribing tadalafil.
ATMEKSI (atomoxetine) is a selective norepinephrine reuptake inhibitor (NRI) indicated for ADHD. It has a slower onset of action (2-4 weeks) compared to stimulants. Monitor for hepatotoxicity and suicidal ideation, especially in children and adolescents. Use cautiously with hepatic impairment (reduce dose) and CYP2D6 poor metabolizers (need lower dose). Avoid concurrent MAOIs. May cause orthostatic hypotension and urinary retention.
Take the medication at the same time daily with or without food.,Seek emergency care for erections lasting longer than 4 hours.,Inform your doctor about all medications, especially nitrates or alpha-blockers.,Finasteride may reduce PSA levels; do not stop taking before PSA testing without consulting your doctor.,Avoid grapefruit juice as it may increase side effects.,Tadalafil may cause dizziness or syncope; avoid driving if affected.
Take ATMEKSI exactly as prescribed; do not change dose without consulting your doctor.,It may take 2-4 weeks to notice improvement in symptoms.,Avoid alcohol and grapefruit juice as they may affect drug levels.,Report any signs of liver problems (yellowing of skin/eyes, dark urine, abdominal pain) or suicidal thoughts immediately.,May cause dizziness or fainting, especially when standing up; rise slowly.,Do not stop abruptly without medical advice.
"Tadalafil, a phosphodiesterase-5 (PDE5) inhibitor, potentiates the hypotensive effect of trandolapril, an angiotensin-converting enzyme (ACE) inhibitor, by enhancing cyclic guanosine monophosphate (cGMP)-mediated vasodilation. This additive hemodynamic effect can lead to symptomatic hypotension, particularly in patients with volume depletion, pre-existing low blood pressure, or those on multiple antihypertensives. Clinically, this interaction manifests as a risk of excessive blood pressure reduction, especially when tadalafil is taken within 4-6 hours of trandolapril administration."
"Posaconazole, an azole antifungal, is a potent inhibitor of CYP3A4, while tadalafil is a CYP3A4 substrate. Coadministration significantly increases tadalafil exposure, leading to elevated risk of adverse effects such as hypotension, syncope, and priapism. The interaction is well-documented and requires dose adjustment or avoidance."
"Tadalafil, a phosphodiesterase-5 (PDE5) inhibitor, potentiates the vasoconstrictive and hypertensive effects of xylometazoline, an alpha-1 adrenergic receptor agonist. This occurs through tadalafil's inhibition of cGMP degradation in vascular smooth muscle, which counteracts the normal nitric oxide-mediated vasodilation and enhances the pressor response to alpha-agonists. Clinically, this interaction can lead to excessive and prolonged increases in blood pressure, potentially resulting in hypertensive crisis, especially in patients with underlying cardiovascular conditions."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about FINASTERIDE AND TADALAFIL vs ATMEKSI, answered by our medical review team.
FINASTERIDE AND TADALAFIL is a PDE5 Inhibitor that works by Finasteride is a 5α-reductase inhibitor that inhibits conversion of testosterone to dihydrotestosterone (DHT). Tadalafil is a phosphodiesterase-5 (PDE5) inhibitor that enhances nitric oxide-mediated vasodilation by increasing cyclic guanosine monophosphate (c GMP) in smooth muscle.. ATMEKSI is a PDE5 Inhibitor that works by ATMEKSI (atazanavir/cobicistat) is a fixed-dose combination of atazanavir, an HIV-1 protease inhibitor that inhibits viral protease, preventing cleavage of viral polyproteins and resulting in immature non-infectious virions, and cobicistat, a pharmacokinetic enhancer that inhibits CYP3A, increasing atazanavir exposure.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between FINASTERIDE AND TADALAFIL and ATMEKSI depend on the specific clinical indication. These are both PDE5 Inhibitor agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of FINASTERIDE AND TADALAFIL is: One capsule containing finasteride 5 mg and tadalafil 5 mg orally once daily.. The standard adult dose of ATMEKSI is: 1.5 mg/kg IV every 4 weeks. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between FINASTERIDE AND TADALAFIL and ATMEKSI in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. FINASTERIDE AND TADALAFIL is classified as Category A/B. Finasteride: Contraindicated in pregnancy due to risk of hypospadias in male fetuses (Category X). Tadalafil: Category B; no fetal harm in animal studies, but insufficient human da. ATMEKSI is classified as Category C. First trimester: Limited human data; animal studies show no teratogenicity at therapeutic doses. Second and third trimesters: No known fetal risks. Avoid use during organogenesis u. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.