Top 300 Pharmacy Drug Cards

SILDENAFIL: Viagra, Various

Class: Erectile Dysfunction Agent

Dosage Forms. Oral Tablet: 20 mg, 25 mg, 50 mg, 100 mg

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Common FDA Label Indication, Dosing, and Titration.

1. Erectile dysfunction: 20-100 mg po as needed prior to anticipated sexual activity

2. Pulmonary hypertension: 20 mg po tid

Off-Label Uses.

1. Sexual dysfunction associated with antidepressant or antipsychotic use: 20-100 mg po as needed prior to anticipated sexual activity

2. Female sexual arousal dysfunction: 20-100 mg po as needed prior to anticipated sexual activity

MOA. Inhibition of phosphodiesterase type 5 (PDE5) by tadalafil enhances erectile function by increasing the amount of cyclic GMP. Penile erection during sexual stimulation is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cyclic guanosine monophosphate (GMP) in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum.

Drug Characteristics: Sildenafil

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Medication Safety Issues: Sildenafil

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Drug Interactions: Sildenafil

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Adverse Reactions: Sildenafil

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Efficacy Monitoring Parameters. Improvement in sexual function.

Toxicity Monitoring Parameters. Seek medical attention if severe skin rash, chest pain, erection lasting more than 4 h, tinnitus, dizziness, or shortness of breath.

Key Patient Counseling Points. Take 60 min prior to anticipated sexual activity, but do not take more frequently than once q24h.

Clinical Pearls. The choice between tadalafil, sildenafil, or vardenafil is largely one of patient preference; tadalafil would be indicated in those desiring “full-day coverage.” Sexual stimulation is required to initiate the local release of nitric oxide; the inhibition of PDE5 has no effect in the absence of sexual stimulation. Dose-dependent increase in mortality in children using for pulmonary artery hypertension; use alternative agent if possible.