STAXYN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for STAXYN (STAXYN).
Selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). By inhibiting PDE5, sildenafil increases intracellular cGMP levels in the corpus cavernosum, enhancing the relaxant effect of nitric oxide (NO) on smooth muscle cells, thereby facilitating penile erection in response to sexual stimulation.
| Metabolism | Primarily metabolized by hepatic CYP3A4 (major) and CYP2C9 (minor) isoenzymes. The major metabolite is N-desmethyl sildenafil, which has a PDE5 selectivity profile similar to the parent drug and contributes to the pharmacological activity. |
| Excretion | Renal (approximately 90% as metabolites, <2% unchanged); fecal (10%) |
| Half-life | Terminal elimination half-life is approximately 4-5 hours; clinically, no accumulation with once-daily dosing |
| Protein binding | 96% bound to plasma proteins (albumin and alpha-1 acid glycoprotein) |
| Volume of Distribution | Approximately 2 L/kg; suggests extensive tissue distribution |
| Bioavailability | 41% (oral); increased to 71% when taken with a high-fat meal |
| Onset of Action | Orally disintegrating tablet: 14-60 minutes |
| Duration of Action | Up to 4 hours; sexual stimulation is required for effect |
| Molecular Weight | 466.53 |
10 mg sublingually as needed, 30–60 minutes before sexual activity. Maximum 1 dose per 24 hours.
| Dosage form | TABLET, ORALLY DISINTEGRATING |
| Renal impairment | No adjustment for mild to moderate impairment. Not recommended for severe renal impairment (CrCl <30 mL/min). |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). For mild to moderate (Child-Pugh A or B), no adjustment but caution advised. |
| Pediatric use | Not indicated in pediatric patients (age <18 years). |
| Geriatric use | No adjustment required for elderly; consider lower starting dose (5 mg) in patients >65 years due to decreased clearance. |
| 1st trimester | Contraindicated due to risk of fetal toxicity and lack of data. |
| 2nd trimester | Contraindicated due to risk of fetal toxicity and lack of data. |
| 3rd trimester | Contraindicated due to risk of fetal toxicity and lack of data. |
Clinical note
Comprehensive clinical and safety monograph for STAXYN (STAXYN).
| Placental transfer | Crosses placenta; exact extent unknown but presumed significant based on molecular weight and lipophilicity. |
| Breastfeeding | Excretion in breast milk unknown; due to potential for serious adverse effects in nursing infants, discontinue drug or nursing. |
| Lactation Rating |
■ FDA Black Box Warning
None
| Serious Effects |
Concomitant use with nitrates or nitric oxide donorsSevere hepatic impairmentHypotension (systolic BP <90 mmHg)Recent stroke or myocardial infarctionKnown hypersensitivity to vardenafil or any excipientUse with riociguat or other guanylate cyclase stimulators
| Precautions | Risk of priapism: erections lasting >4 hours require immediate medical attention., Co-administration with alpha-blockers may cause symptomatic hypotension., Not recommended in patients with pulmonary veno-occlusive disease., Use with caution in patients with anatomical deformation of the penis (angulation, cavernosal fibrosis, Peyronie's disease)., Cardiovascular risk: sexual activity may pose a risk in patients with underlying cardiovascular disease. |
| Food/Dietary | Avoid high-fat meals as they delay and reduce absorption of vardenafil. Grapefruit juice may increase drug levels and risk of side effects. |
Loading safety data…
| L5 (Contraindicated) |
| Teratogenic Risk | FDA Pregnancy Category B. No evidence of teratogenicity in animal studies; no adequate human studies in first trimester. Caution in second and third trimesters due to potential for uterine hyperstimulation and fetal distress associated with vasodilation. |
| Fetal Monitoring | Monitor maternal blood pressure and heart rate during use. Assess fetal heart rate if used for erectile dysfunction during pregnancy (off-label). Uterine monitoring may be warranted due to risk of hyperstimulation. |
| Fertility Effects | No known adverse effects on fertility in animal studies. In humans, vasodilation may impair erectile function, but no direct effect on spermatogenesis or ovarian function has been reported. |
| Clinical Pearls | Staxyn (vardenafil orodispersible tablet) is a PDE5 inhibitor used for erectile dysfunction. It has a faster onset (15-25 minutes) compared to sildenafil. Avoid use with nitrates or alpha-blockers due to risk of hypotension. Counsel patients to take on an empty stomach for best absorption. Not recommended for use with potent CYP3A4 inhibitors like ketoconazole or ritonavir. |
| Patient Advice | Place the tablet on the tongue and allow it to dissolve; do not take with water. · Take 15-25 minutes before sexual activity; do not take more than once daily. · Do not use if taking nitrates for chest pain or alpha-blockers for prostate problems. · Common side effects include headache, flushing, and nasal congestion. Seek immediate help if vision loss or erection lasting >4 hours occurs. · Avoid grapefruit juice as it may increase drug levels. |