STENDRA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for STENDRA (STENDRA).
Selective inhibitor of phosphodiesterase type 5 (PDE5), enhancing cyclic guanosine monophosphate (cGMP) accumulation in corpus cavernosum, leading to smooth muscle relaxation and increased penile blood flow.
| Metabolism | Primarily hepatic through CYP3A4, with minor contribution from CYP2C9; metabolite M1 also active. |
| Excretion | Fecal (approximately 63%) and renal (approximately 21%) as metabolites; less than 2% excreted unchanged in urine. |
| Half-life | Terminal elimination half-life is approximately 4 hours in healthy subjects; may be prolonged in hepatic impairment (Child-Pugh B: up to 6 hours) or with concomitant CYP3A4 inhibitors. |
| Protein binding | Approximately 99% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Approximately 2 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is approximately 40% under fasting conditions; reduced by 30–40% when taken with a high-fat meal. |
| Onset of Action | Oral: Approximately 30–60 minutes; maximal effect within 1–2 hours under fasting conditions. |
| Duration of Action | Up to 4–6 hours; clinical efficacy may persist up to 12 hours in some patients, but recommended dosing interval is once daily as needed. |
50 mg orally once daily as needed, 1 hour before sexual activity. Maximum dose 100 mg. Maximum frequency once daily.
| Dosage form | TABLET |
| Renal impairment | CrCl 30-50 mL/min: 50 mg initially. CrCl <30 mL/min: not recommended. |
| Liver impairment | Child-Pugh A: 50 mg initially. Child-Pugh B: 25 mg initially. Child-Pugh C: not recommended. |
| Pediatric use | Not approved for pediatric use. |
| Geriatric use | No specific adjustment. Consider lower starting dose (25 mg) due to age-related decreased clearance. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for STENDRA (STENDRA).
| Breastfeeding | Excretion into human milk is unknown; however, based on pharmacokinetics and molecular weight (sildenafil citrate, MW 666.7), minimal excretion is expected. M/P ratio not established. Avoid use in breastfeeding women or use with caution due to potential adverse effects on the infant (e.g., hypotension, priapism). |
| Teratogenic Risk | Pregnancy Category B: Animal studies have not demonstrated fetal risk, but no adequate human studies in pregnant women. Use only if clearly needed. First trimester: No known teratogenic effects. Second and third trimesters: No documented adverse fetal outcomes. However, due to potential uterine hyperstimulation and placental hypoperfusion, avoid use in pregnancy unless benefit outweighs risk. |
■ FDA Black Box Warning
None
| Serious Effects |
["Concurrent use of organic nitrates (any form)","Concurrent use of guanylate cyclase stimulators (e.g., riociguat)","Hypersensitivity to avanafil or any component"]
| Precautions | ["Cardiovascular risk: use with caution in patients with left ventricular outflow obstruction, hypotension, or severe hepatic impairment.","Avoid use with nitrates due to risk of severe hypotension.","Priapism: advise patients to seek immediate medical attention if erection persists >4 hours.","Hearing loss: rare cases of sudden decrease or loss of hearing."] |
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| Fetal Monitoring | Monitor maternal blood pressure and heart rate during treatment. Fetal monitoring should include heart rate assessment if administered near term due to possibility of uterine hyperstimulation. In cases of overdose or prolonged erection, monitor for signs of priapism. |
| Fertility Effects | No specific studies on fertility. In animal studies, no impairment of fertility was observed at doses up to 60 mg/kg/day (approximately 25 times the MRHD). There is no evidence of permanent adverse effects on fertility in humans. |