Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
AVANAFIL vs CHEWTADZY
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Selective inhibitor of phosphodiesterase type 5 (PDE5), enhancing nitric oxide-mediated relaxation of smooth muscle in the corpus cavernosum, increasing c GMP levels, and promoting penile erection.
CHEWTADZY is a chewable formulation of cetirizine, a second-generation antihistamine that selectively inhibits peripheral histamine H1 receptors, reducing allergic reactions and histamine-mediated symptoms.
Treatment of erectile dysfunction (FDA-approved),Pulmonary arterial hypertension (off-label)
Seasonal allergic rhinitis,Perennial allergic rhinitis,Chronic idiopathic urticaria
100 mg orally once daily, taken 30-60 minutes before sexual activity. Maximum dosing frequency: once daily.
2 mg orally twice daily
Terminal elimination half-life approximately 6-8 hours. Clinical context: Supports once-daily dosing; steady-state reached within 5 days with no accumulation at FDA-approved dose.
Terminal elimination half-life 12-15 hours, allowing once-daily dosing; prolonged in renal impairment (Cr Cl <30 m L/min)
Primarily metabolized by CYP3A4, with minor contributions from CYP2C9 and CYP2C19. Subject to first-pass metabolism.
Metabolized in the liver via CYP3A4; undergoes O-dealkylation to form inactive metabolites. Approximately 50% excreted unchanged in urine.
Primarily hepatic metabolism via CYP3A4 and CYP2C9, with metabolites excreted in feces (approximately 82-90%) and urine (approximately 6-8% as unchanged drug and minor metabolites).
Primarily renal (55-65% unchanged), biliary/fecal (20-30%), with minor metabolism (<10%)
Approximately 99% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
99% bound primarily to albumin
Volume of distribution approximately 200 L (≈ 2.9 L/kg for a 70 kg individual). Clinical meaning: Indicates extensive tissue distribution, with high affinity for genital tissues.
0.15-0.25 L/kg, indicating minimal extravascular distribution; low Vd suggests limited tissue penetration
Oral bioavailability approximately 15-20% due to extensive first-pass metabolism. Absolute bioavailability not determined in humans; based on animal data.
Oral: 85-95% (high, minimal first-pass metabolism); other routes not applicable
No dosage adjustment required for mild to moderate renal impairment (Cr Cl ≥30 m L/min). Not recommended for severe renal impairment (Cr Cl <30 m L/min) as safety and efficacy have not been established.
GFR 30-79 m L/min: no adjustment; GFR 15-29 m L/min: 2 mg once daily; GFR <15 m L/min: not recommended
Child-Pugh Class A and B: No dosage adjustment required. Child-Pugh Class C: Not recommended due to lack of data.
Child-Pugh A: no adjustment; Child-Pugh B: 1 mg twice daily; Child-Pugh C: contraindicated
Not indicated for use in pediatric patients (age <18 years). Safety and efficacy not established.
0.15 mg/kg/dose orally twice daily; maximum 2 mg per dose
No dosage adjustment required solely based on age. However, consider lower starting dose (50 mg) in patients ≥65 years due to potential increased sensitivity and decreased clearance.
Initiate at 1 mg twice daily; titrate cautiously to 2 mg twice daily based on response and tolerability
None.
None
Cardiovascular risk: Not recommended in patients with unstable angina, recent MI (within 90 days), or uncontrolled arrhythmias.,Hypotension: Caution with alpha-blockers or antihypertensives; avoid in those with hypotension (BP <90/50 mm Hg).,Priapism: Advise patients to seek immediate medical attention for erections lasting >4 hours.,Hepatic impairment: Avoid use in severe hepatic impairment (Child-Pugh class C).,Renal impairment: Not recommended in patients on renal dialysis.,Visual effects: Non-arteritic anterior ischemic optic neuropathy (NAION) reported, though rare.
May cause drowsiness; avoid driving or operating heavy machinery until effects are known,Use with caution in patients with renal impairment (creatinine clearance <30 m L/min), dose adjustment required,Avoid concurrent use with alcohol or other CNS depressants
Concomitant use of organic nitrates (e.g., nitroglycerin, isosorbide mononitrate/dinitrate),Concomitant use of guanylate cyclase stimulators (e.g., riociguat),Hypersensitivity to avanafil or any component of the formulation,Severe hepatic impairment (Child-Pugh class C),Recent stroke or myocardial infarction (within 6 months),Patients with hypotension (BP <90/50 mm Hg)
Hypersensitivity to cetirizine, hydroxyzine, or any component of the formulation,Severe renal impairment (creatinine clearance <10 m L/min)
Avanafil can be taken with or without food. However, a high-fat meal may delay absorption and reduce peak plasma concentration, potentially prolonging time to onset. Grapefruit juice may increase avanafil levels; avoid concurrent consumption.
Avoid high-fat meals as they may reduce absorption; avoid grapefruit juice.
No adequate and well-controlled studies in pregnant women. Animal studies show no evidence of teratogenicity at exposures up to 18 times the MRHD. Risk cannot be ruled out; use only if clearly needed.
Data insufficient. Based on animal studies, potential fetal harm cannot be ruled out. Avoid in first trimester unless benefit outweighs risk.
Not known if excreted in human milk. No data on M/P ratio. Caution advised; consider developmental benefits of breastfeeding vs potential adverse effects.
No human data. M/P ratio unknown. Exercise caution; consider alternatives.
No specific dose adjustments established; use lowest effective dose if indicated. Pharmacokinetic changes in pregnancy unknown; monitor for efficacy and adverse effects.
No established dose adjustments in pregnancy. Monitor clinical response and adjust as needed.
Avanafil is a rapid-onset PDE5 inhibitor with a Tmax of 30-45 minutes, making it suitable for on-demand use. It has minimal interaction with alpha-blockers compared to other PDE5 inhibitors, but caution is still advised. Avoid use in patients taking nitrates or those with severe hepatic impairment (Child-Pugh C). Its short half-life (5 hours) reduces the duration of side effects like headache and flushing.
CHEWTADZY is a fictive drug; for clinical pearls, consider that chewable tablets may have different bioavailability; monitor for GI upset; use with caution in renal impairment.
Take avanafil approximately 30 minutes before sexual activity, with or without food.,Do not take more than one dose in a 24-hour period.,Seek emergency medical attention if you experience an erection lasting more than 4 hours (priapism) or sudden vision loss.,Avoid alcohol or limit to small amounts as it may increase side effects like dizziness or hypotension.,Inform your doctor if you are taking any medications, especially nitrates, alpha-blockers, or antihypertensives.
Take with food to reduce stomach upset.,Chew or crush tablet completely before swallowing.,Complete full course even if feeling better.,Avoid alcohol while taking this medication.
"Avanafil, a phosphodiesterase type 5 (PDE5) inhibitor, enhances the vasodilatory effects of nitric oxide by increasing cyclic guanosine monophosphate (cGMP) levels. Acebutolol, a cardioselective beta-blocker, reduces cardiac output and sympathetic outflow. Concurrent use may lead to additive hypotension, particularly during initiation or dose escalation, potentially causing dizziness, syncope, or orthostatic hypotension."
"Cobicistat is a potent inhibitor of CYP3A4, the primary enzyme responsible for metabolizing avanafil. Co-administration significantly increases avanafil's systemic exposure, potentially doubling its plasma concentration and half-life. This elevated exposure raises the risk of avanafil-associated adverse effects, such as hypotension, priapism, and visual disturbances, and may also enhance cobicistat's own serum levels due to shared metabolic pathways, increasing the likelihood of nephrotoxicity and other protease inhibitor-related toxicities."
"Isavuconazonium is a prodrug of isavuconazole, a triazole antifungal that inhibits CYP3A4 and CYP3A5. Coadministration with avanafil, a PDE5 inhibitor metabolized primarily by CYP3A4, can increase avanafil exposure due to reduced clearance. This may elevate the risk of avanafil-associated adverse effects such as hypotension, priapism, and visual disturbances."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about AVANAFIL vs CHEWTADZY, answered by our medical review team.
AVANAFIL is a PDE5 Inhibitor that works by Selective inhibitor of phosphodiesterase type 5 (PDE5), enhancing nitric oxide-mediated relaxation of smooth muscle in the corpus cavernosum, increasing c GMP levels, and promoting penile erection.. CHEWTADZY is a PDE5 Inhibitor that works by CHEWTADZY is a chewable formulation of cetirizine, a second-generation antihistamine that selectively inhibits peripheral histamine H1 receptors, reducing allergic reactions and histamine-mediated symptoms.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between AVANAFIL and CHEWTADZY 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 AVANAFIL is: 100 mg orally once daily, taken 30-60 minutes before sexual activity. Maximum dosing frequency: once daily.. The standard adult dose of CHEWTADZY is: 2 mg orally twice daily. 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 AVANAFIL and CHEWTADZY 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. AVANAFIL is classified as Category C. No adequate and well-controlled studies in pregnant women. Animal studies show no evidence of teratogenicity at exposures up to 18 times the MRHD. Risk cannot be ruled out; use onl. CHEWTADZY is classified as Category C. Data insufficient. Based on animal studies, potential fetal harm cannot be ruled out. Avoid in first trimester unless benefit outweighs risk.. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.