PDE-5 inhibitors

PDE-5 inhibitors

Drug monograph · NCLEX study reference
Trade names	Viagra, Revatio, Cialis, Adcirca
Therapeutic class	Erectile dysfunction agent, pulmonary hypertension agent, benign prostatic hyperplasia (tadalafil)
Pharmacologic class	Phosphodiesterase-5 inhibitors
Onset / peak / duration	Sildenafil onset 30 to 60 minutes; tadalafil longer acting (up to 36 hours).
Half-life / level	Sildenafil about 4 hours, tadalafil about 17.5 hours; no routine level.
Routes	PO (oral)
High-alert (ISMP)	No
Black box warning	None
Antidote / reversal	Supportive care.
Pregnancy / lactation	Pulmonary hypertension use case by case.

Nursing pharmacology study reference (NCLEX-style monograph). Numeric values are standard teaching ranges for study and must be verified against current manufacturer labeling before clinical use. This is educational content, not prescribing guidance.

PDE-5 inhibitors (brand names Viagra, Revatio, Cialis, Adcirca) — Erectile dysfunction agent, pulmonary hypertension agent, benign prostatic hyperplasia (tadalafil); Phosphodiesterase-5 inhibitors.

Identification

• Therapeutic class: Erectile dysfunction agent, pulmonary hypertension agent, benign prostatic hyperplasia (tadalafil).
• Pharmacologic class: Phosphodiesterase-5 inhibitors.

Pharmacology

• Mechanism of action: Inhibit PDE-5 to enhance nitric oxide-mediated vasodilation in the penis and pulmonary vasculature.
• Onset / peak / duration: Sildenafil onset 30 to 60 minutes; tadalafil longer acting (up to 36 hours).
• Half-life / therapeutic level: Sildenafil about 4 hours, tadalafil about 17.5 hours; no routine level.

Clinical use

• Indications: Erectile dysfunction, pulmonary arterial hypertension, benign prostatic hyperplasia (tadalafil).
• Usual dose, route, frequency: PO as needed before activity (erectile dysfunction) or daily (pulmonary hypertension, BPH).
• Maximum dose / adjustments: Reduce with strong CYP3A4 inhibitors and in hepatic or renal impairment; lower doses with alpha blockers.

Safety

• Contraindications: Concurrent nitrates in any form, recent severe cardiovascular event, severe hypotension.
• Black box warning: None.
• Interactions: Nitrates (life-threatening hypotension, absolute contraindication), alpha blockers (hypotension), CYP3A4 inhibitors, riociguat.
• Pregnancy / lactation: Pulmonary hypertension use case by case.
• High-alert: No.

Adverse effects

• Common side effects: Headache, flushing, nasal congestion, dyspepsia, visual color changes.
• Serious effects to report: Priapism (erection over 4 hours, an emergency), sudden vision loss (NAION), sudden hearing loss, severe hypotension.
• Antidote / reversal: Supportive care.

Nursing process

• Assessment before administration: Cardiovascular status, nitrate use, blood pressure.
• Interventions during therapy: Confirm no nitrate use; counsel on priapism.
• Monitor: Blood pressure, response, vision and hearing changes.
• Evaluation / expected outcome: Improved erectile function or pulmonary pressures.

Patient teaching

• Patient teaching: Never combine with nitrates or recreational nitrites (poppers); seek emergency care for an erection lasting over 4 hours or sudden vision or hearing loss.
• Notify provider if: Erection over 4 hours, sudden vision or hearing change, chest pain.
• Administration tips: Take before activity (erectile dysfunction); avoid high-fat meals with sildenafil (delays onset).