vardenafil hydrochloride

vardenafil hydrochloride

(var den' ah fill)

Levitra

Pregnancy Category B

Drug classes

Impotence drug

Phosphodiesterase type 5 inhibitor

Therapeutic actions

Selectively inhibits cGMP-specific phosphodiesterase type 5. The mechanism of penile erection involves the release of nitric oxide into the corpus cavernosum of the penis during sexual stimulation. Nitrous oxide activates cGMP, which causes smooth muscle relaxation allowing the flow of blood into the corpus cavernosum. Vardenafil prevents the breakdown of cGMP by phosphodiesterase, leading to increased cGMP levels and prolonged smooth muscle relaxation promoting the flow of blood into the corpus cavernosum.

Indications

·        Treatment of erectile dysfunction occurring in the presence of sexual stimulation

Contraindications and cautions

·        Contraindicated with allergy to any component of the tablet, for women or children; concurrent use of nitrates or alpha blockers

·        Use cautiously with hepatic or renal dysfunction; with anatomic deformation of the penis, with known cardiac disease (effects of sexual activity need to be evaluated), congenital prolonged QT interval, unstable angina; hypotension (systolic < 90); uncontrolled hypertension (> 170/110), severe hepatic impairment; end stage renal disease with dialysis; hereditary degenerative retinal disorders.

Available forms

Tablets—2.5, 5, 10, 20 mg

Dosages

ADULTS

5–10 mg PO taken 1 hr before anticipated sexual activity; range 5–20 mg PO. Limit use to once per day.

PEDIATRIC PATIENTS

Not intended for use in children.

GERIATRIC PATIENTS AND THOSE WITH MODERATE HEPATIC IMPAIRMENT

Starting dose of 5 mg PO is suggested.

Pharmacokinetics

Route	Onset	Peak
Oral	Rapid	30–120 min

Metabolism: Hepatic, T_1/2 : 4–5 hr

Distribution: Not intended for use in women, no clear studies on crossing the placenta or entering breast milk

Excretion: Feces

Adverse effects

·        CNS: Headache, abnormal vision, dizziness, hypertonia, insomnia, somnolence, vertigo, ischemic optic neuropathy

·        CV: Flushing, angina, chest pain, hypertension, hypotension, MI, palpitation, postural hypotension, tachycardia

·        GI: Dyspepsia, diarrhea, abdominal pain, dry mouth, esophagitis, gastritic, GERD

·        GU: Abnormal ejaculation, priapism

·        Respiratory: Rhinitis, sinusitis, dyspnea, epistaxis, pharyngitis

·        Other: Flulike syndrome, edema, pain, rash, sweating

Interactions

Drug-drug

·        WARNING: Possible severe hypotension and serious cardiac events if combined with nitrates, alpha blockers; this combination must be avoided.

·        Possible increased vardenafil levels and effects if taken with ketoconazole, itraconazole, erythromycin; monitor patient and reduce dosage as needed

·        Increased vardenafil serum levels if combined with indinavir, ritonavir; if these drugs are being used, limit vardenafil dose to 2.5 mg in a 24-hr period

Nursing considerations

Assessment

·        History: Allergy to any component of the tablet, concurrent use of nitrates or alpha blockers; unstable angina; hypotension; uncontrolled hypertension; severe hepatic impairment; end-stage renal disease with dialysis; hereditary degenerative retinal disorders; anatomical deformation of the penis, cardiac disease, congenital prolonged QT interval

·        Physical: Orientation, affect; skin color, lesions; R, adventitious sounds; P, BP, ECG, LFTs, renal function tests

Interventions

·        Ensure diagnosis of erectile dysfunction and determine underlying causes and other appropriate treatment.

·        Advise patient that drug does not work without sexual stimulation. Limit use to once per day.

·        Remind patient that drug does not protect against sexually transmitted diseases and appropriate measures should be taken.

·        WARNING: Advise patient to never take this drug with nitrates or alpha blockers; serious and even fatal complications can occur.

Teaching points

·        Take this drug 60 minutes before anticipated sexual activity. The drug will have no effect unless there is sexual stimulation.

·        This drug will not protect you from sexually transmitted diseases; use appropriate precautions.

·        Do not take this drug if you are taking any nitrates or alpha blockers; serious side effects or death can occur.

·        Many drugs may interact with vardenafil; always consult your health care provider before taking any drug, including over-the-counter drugs and herbal therapies; dosage adjustments may be needed.

·        You may experience these side effects: Headache, dizziness, upset stomach, runny nose; these side effects should go away within a couple of hours. If side effects persist, consult your health care provider.

·        Stop drug and consult your health care provider immediately if you experience sudden loss of vision.

·        Report difficult or painful urination, vision changes, fainting, erection that persists for longer than 4 hours, sudden loss of vision.

Adverse effects in Italic are most common; those in Bold are life-threatening.