Brand names: Caverject, edex, Muse, Prostin VR Pediatric
Drug class: Direct Vasodilators

Medically reviewed by Drugs.com on May 10, 2024. Written by ASHP.

Introduction

Vasodilator and platelet-aggregation inhibitor; a naturally occurring prostaglandin E₁.^{1 5 20 98}

Uses for Alprostadil (Systemic, Local)

Erectile Dysfunction

Used to facilitate attainment of a sexually functional erection in males with erectile dysfunction (ED, impotence).^{98 110 b}

Intraurethral therapy generally preferred over intracavernosal vasoactive therapy because it is less invasive; however intracavernosal therapy is most effective nonsurgical treatment for ED.¹¹²

Consider intraurethral therapy for patients with inadequate responses to or who are not candidates for selective oral PDE type 5 inhibitor therapy.¹¹²

Effective in patients with organic (neurogenic and/or mild to moderate vasculogenic) ED or with psychogenic ED.^{19 20 24 25 27 34 36 41 45 46 64 67 71}

Experts recommend a selective PDE type 5 inhibitor as first-line therapy for ED unless contraindicated.^{189 601 602}

Manufacturers state that safety and efficacy of alprostadil in combination with other vasoactive therapy for erectile dysfunction not established and currently not recommended.^{64 101 b} However, American Urological Association (AUA) and other clinicians state that combination therapy with other intracavernosal vasoactive agents increased efficacy and decreased adverse effects relative to alprostadil alone.^{9 10 11 12 14 15 17 18 21 65 71 90 91 y z} Combined therapy with intraurethral alprostadil and vacuum constriction device or oral selective PDE type 5 inhibitor increased efficacy relative to alprostadil alone.¹¹²

Adjunct to other vascular testing (e.g., duplex ultrasonography, cavernosometry/cavernosography, angiography, radioisotope penogram) in differential diagnosis of ED and evaluation of hemodynamic status of erectile tissue.^{5 15 16 17 21 24 27 28 65 66 67 110 b}

Ductus Arteriosus-dependent Congenital Heart Disease

Palliative treatment in maintaining patency of ductus arteriosus in neonates with various ductal-dependent congenital heart defects (e.g., pulmonary atresia, pulmonary stenosis, tricuspid atresia, tetralogy of Fallot, interruption of aortic arch, coarctation of the aorta, transposition of great vessels).^{1 3 29 42 43 44 47 51 56 57 60}

Used to provide adequate circulation and oxygenation and prevent or correct resultant acidemia until corrective or palliative surgery can be performed.^{1 3 42 43 44 47 49 51 52 53 54 55 56 60}

Do not use in neonates with respiratory distress syndrome.^{1 4 42 49 64}

Alprostadil (Systemic, Local) Dosage and Administration

General

ED

• Initiate and titrate dosage in medical setting (e.g., clinician’s office);^{7 23 34 65 98 101 110 112 b} patient must remain in this setting until complete detumescence occurs.^{5 19 32 64 112 b d h}

• Carefully individualize dosage according to patient’s erectile response^{5 8 12 19 32 34 89 98 99 100 101 107 b} toward therapeutic goal of achieving erection satisfactory for intercourse, but persists for ≤1 hour.^{5 12 34 69 89 97 98 b h}

• Titrate dosage slowly to lowest possible effective level to avoid priapism.^{5 12 19 32 101 b} Erections persisting >1 hour increase risk of priapism.^{5 12 34 69 89 97 98 b h}

• Initiate maintenance home treatment regimens at dosage determined as optimal during titration in medical setting.^{97 98 b d f} Further dosage adjustments may be required.^{b d f i} Dosage determined by clinician in medical setting should not be changed without consulting clinician.^{b e f i r}

Ductus Arteriosus-dependent Congenital Heart Disease

• Use only by trained personnel in facilities providing pediatric intensive care.^{1 3 44 50 53 60} Monitor respiratory status of neonate throughout administration; facilities and equipment for assisted ventilation should be readily available.^{1 50} (See Boxed Warning.)

• Adjust dosage using lowest possible effective dosage for shortest period necessary to provide desired effects.¹

• If long-term infusion considered (e.g., when surgery deferred in poor-risk neonate), carefully weigh risks of prolonged therapy against anticipated benefits.^{1 44 47 49 50 54 55 58 59}

• In neonates with restricted pulmonary blood flow, monitor measures of improved blood oxygenation.^{1 3 29 42 43 44 54 56 57 60 70}

• In neonates with restricted systemic blood flow, monitor measures of improved systemic BP and blood pH.^{1 3 29 43 44 48 51 54 56 57 60}

• Periodically monitor arterial BP via umbilical artery catheter, auscultation, or Doppler transducer.^{1 50}

Administration

Administer by continuous IV or intra-arterial infusion to maintain patency of ductus arteriosus in neonates with congenital heart disease.¹

Administer by intracavernosal injection for treatment and diagnosis of ED or by intraurethral suppository for treatment of ED.^{97 98 100 101 b}

IV and Intra-arterial Infusion

To maintain patency of ductus arteriosus, administer by continuous IV infusion into a large vein (peripheral or central);^{1 44} preferred route of administration.^{1 3 50}

Alternatively, may administer through an umbilical artery catheter placed at the ductal opening.¹

If flushing occurs during intra-arterial infusion, reposition catheter.¹

A controlled-infusion device (e.g., an electronic volumetric controller, volumetric IV infusion pump) or other apparatus to ensure precise control of the flow rate should be used; inadvertent rapid administration could result in toxicity (e.g., apnea).^{1 50 60 70} (See Boxed Warning.)

Standardize 4 Safety

Standardized concentrations for IV alprostadil have been established through Standardize 4 Safety (S4S), a national patient safety initiative to reduce medication errors, especially during transitions of care.²⁴⁹ Multidisciplinary expert panels were convened to determine recommended standard concentrations. ²⁴⁹ Because recommendations from the S4S panels may differ from the manufacturer’s prescribing information, caution is advised when using concentrations that differ from labeling, particularly when using rate information from the label.²⁴⁹ For additional information on S4S (including updates that may be available), see [Web]. ²⁴⁹

Dilution

Alprostadil injection concentrate must be diluted prior to IV or intra-arterial infusion.¹

Add 1 mL of alprostadil concentrate to 0.9% sodium chloride or 5% dextrose injection to provide solution containing 2–20 mcg/mL of drug, depending on controlled-infusion device employed and needs of neonate.^{1 64}

When using a device with a volumetric infusion chamber, add appropriate volume of diluent to chamber first and then add 1 mL of drug concentrate to diluent.¹

The following table lists sample alprostadil dilutions and infusion rates when a dosage of 0.1 mcg/kg of body weight per minute is employed.¹ This dosage is commonly used for initiation of alprostadil therapy to maintain patency of the ductus arteriosus.¹

Intracavernosal Administration

Administer by intracavernosal injection into the penis.^{22 24 27 67 69 71 83 89 101 e i r}

Vary injection site to minimize adverse effects related to repeated local injection.^{8 89 111 b e r}

Prior to administration using Caverject impulse dual-chambered syringe system, set dose to be delivered by slowly turning the end of the plunger rod clockwise until the number visible in the dose window matches the appropriate dose of the drug (in mcg).¹¹¹

Reconstituted solutions of alprostadil for intracavernosal injection are intended for single-use only.^{2 28 101 110} Properly dispose of single-use delivery device and any remaining solution following use.^{110 111}

Reconstitution

Caverject: Reconstitute vial labeled as containing 20 or 40 mcg of alprostadil powder with 1 mL of bacteriostatic or sterile water for injection (with benzyl alcohol) supplied by manufacturer, to provide a solution containing 20.5 or 41.1 mcg/mL, respectively, and delivering 20 or 40 mcg/mL.^b Use a 3 mL syringe with a 27- to 30-gauge, 0.5-inch needle.^b Swirl contents of vial gently until clear solution obtained.^e Withdraw desired dose of reconstituted solution into same syringe prior to administration.^e

Caverject impulse dual-chambered syringe system: Reconstitute by turning plunger rod clockwise until rod meets resistance^{110 111} to force diluent (sterile bacteriostatic water for injection) into chamber containing sterile powder.¹¹¹ Mix contents of syringe thoroughly by turning device upside down several times until solution is clear.^{110 111}

edex dual-chambered system: Place cartridge containing alprostadil lyophilized powder into edex injection device^r and push plunger of device until 2 gray rubber stoppers touch to force diluent (1.075 mL of 0.9% sodium chloride injection) into upper chamber containing drug powder.^{d r} Gently move injection device back and forth until solution is clear.^r Do not use if cartridge is damaged or cake of drug powder is substantially <(3/8) inch in thickness.¹⁰¹

Intracavernosal Injection Technique

Hold head (glans) of penis (if uncircumcised, pull back foreskin initially) between thumb and forefinger, and stretch lengthwise along thigh while sitting upright or slightly reclined.^{22 24 27 67 69 71 83 89 101 e i r} Inject into a corpus cavernosum of the penis (underneath the tunica albuginea along dorsolateral aspect of proximal third of penis) using a steady motion.^{22 24 27 64 67 69 71 83 89 101 110 111 e i r} Avoid blood vessels, corpus spongiosum, subcutaneous tissue, urethra, and dorsal neural vascular structures as injection sites.^{5 7 8 28 34 83 b d e h i}

Inject dose slowly (over 5–10 seconds);^{22 27 64 71 83 101 110 111 r} apply pressure to injection site with alcohol swab for 5 minutes (or until bleeding stops) after needle is withdrawn.^{7 22 25 67 71 83 89 101 111 e r} If bleeding continues or recurs, abstain from intercourse.^r

If solution does not inject easily or if a burning pain at injection site occurs, reposition needle by moving needle slightly or partially withdrawing needle until solution can be injected easily and painlessly.^{i r}

If needle bends severely at anytime during reconstitution or injection, discard needle, and replace with new unused needle.^e

Rate of Administration

Inject slowly (over 5–10 seconds).^{22 27 64 71 83 101 110 111 r}

Intraurethral Administration

Administer intraurethrally as a suppository.^{97 98 99 100 104 105 106}

Urinate immediately prior to administration and gently shake penis to remove excess urine.^{97 100 105 106} Microsuppository (medicated pellet) is designed to dissolve in small quantity of urine remaining in urethra after urination.⁹⁹

Insert intraurethral suppository according to manufacturer’s instructions.^{97 100} After insertion, inspect applicator to confirm that urethral suppository is no longer in applicator tip.¹⁰⁰ If some residual medication is left in applicator, repeat insertion procedure.¹⁰⁰ Urination or dribbling immediately following intraurethral administration may result in loss of drug from urethral area.¹⁰⁰

After insertion of suppository, hold penis upright, and stretch to its full length.¹⁰⁰ Roll penis firmly between hands for ≥10 seconds to ensure that drug distributes adequately along walls of urethra.¹⁰⁰ If a burning sensation occurs, roll penis for additional 30–60 seconds or until burning subsides.¹⁰⁰

After administration, increase blood flow to penis by sitting, standing, or walking for 10 minutes.^{100 106} Lying down (especially on back) immediately after administration may reduce penile blood flow and subsequent development of erection.^{100 106} During sexual activity, use positions that favor blood flow into penis.¹⁰⁰

Dosage

Pediatric Patients

Ductus Arteriosus-dependent Congenital Heart Disease

IV and Intra-arterial Infusion

Neonates: Initially, 0.1 mcg/kg per minute.^{1 3} However, adequate clinical response reported with 0.05 mcg/kg per minute^{1 70} in some neonates.^{3 43 49 57 58 60 70 95 96}

If response inadequate, may increase dosage gradually up to 0.4 mcg/kg per minute.^{1 3 57 60} However, dosages >0.1 mcg/kg per minute generally have not produced additional benefit.^{1 3 57 60}

After therapeutic response achieved, reduce infusion rate to provide the lowest possible dosage that maintains response; progressively taper dosage from 0.1 down to 0.05 to 0.025 to 0.01 mcg/kg per minute until lowest effective dose reached.^{1 3}

Continue therapy until surgical repair is complete, usually ≤24–48 hours after initiation.^{3 44}

If complications occur, consider lower infusion rate or discontinuance of infusion.^{1 60} (See IV and Intra-arterial Infusion: Rate of Administration under Dosage and Administration.)

If apnea or bradycardia occurs, discontinue infusion and initiate appropriate treatment.^{1 50} In some cases, reinitiate infusion cautiously if continued therapy considered necessary.^{1 3 42 50 64}

Adults

ED

Initiation and Titration for ED of Neurogenic, Vasculogenic, Psychogenic, or Mixed Etiology

Intraurethral Suppository

Initially, 125 or 250 mcg.^{98 105} If no response, increase subsequent doses in a stepwise manner to 500 mcg or 1 mg, as needed, on separate occasions.^{98 107} Use ≤2 urethral suppositories within 24 hours.^{98 100 104}

Initiation and Titration for ED of Pure Neurogenic Etiology

Intracavernosal Injection

Caverject vials and single-use, dual-chambered injection device: Initially, 1.25 mcg.^{89 110 b} If no response, double second dose to 2.5 mcg after ≤1 hour.^{64 110 b} Do not administer >2 doses within 24 hours.^{64 110 x} If additional dosage titration required, administer 5 mcg during next 24 hours.^{110 b} Increase subsequent dosage in 5-mcg increments, with each incremental increase separated by ≥24 hours, until optimum response achieved.^{110 b} (See General: ED, under Dosage and Administration.)

edex reusable dual-chambered injection device: Initially, 1.25 mcg.^d If no response, double second dose to 2.5 mcg after ≤1 hour; if still no response, increase to 5 mcg after ≤1 hour.^{d z} Increase subsequent dosage in 5-mcg increments, until optimum response achieved.^{d z} (See General: ED, under Dosage and Administration.) If a partial response observed at any point in dosage titration, wait ≥1 day before resuming dose titration.^{d z}

Initiation and Titration for ED of Vasculogenic, Psychogenic, or Mixed Etiology

Intracavernosal Injection

Caverject vials and single-use, dual-chambered injection devices: Initially, 2.5 mcg.^{8 110 b} If partial response observed, double dose to 5 mcg after ≤1 hour.^{110 b} If no response, increase second dose to 7.5 mcg after ≤1 hour.^{110 b} Administer ≤2 doses within ≤24 hours.^{110 x} If additional titration required, increase dosage in increments of 5–10 mcg at intervals of ≥24 hours until optimum response achieved.^{110 b z} (See General: ED, under Dosage and Administration.)

edex reusable dual-chambered injection device: Initially, 2.5 mcg.^d If no response, increase second dose to 7.5 mcg after ≤1 hour, followed by increments of 5–10 mcg at intervals of ≤1 hour until a response occurs.^{d z} If partial response observed with 2.5 mcg, wait ≥24 hours before doubling dose to 5 mcg, followed by increments of 5–10 mcg at intervals of ≥24 hours until optimum response achieved.^{d z} (See General: ED, under Dosage and Administration.)

Maintenance (Self-administration)

Intraurethral Suppository

Initially, self-administer dose determined as optimal during titration in a medical setting (e.g., physician’s office);^{97 98} administer ≤2 urethral suppositories within a 24-hour period.^{98 100 104}

Intracavernosal Injection

Initially, self-administer dose determined as optimal during titration in a medical setting (e.g., physician’s office); administer no more frequently than 3 times weekly with >1 day elapsing between each dose.^{2 34 101 b d e h i r}

If required, adjust dosage only after consultation with a clinician (not independently by the patient), following the same initial titration guidelines.^{2 b e f i r}

Diagnostic Use

Intracavernosal Injection

Adjunct to other vascular testing: Use single dose that produces firm erection.^{86 110 b}

Prescribing Limits

Pediatric Patients

Ductus Arteriosus-dependent Congenital Heart Disease

IV or Intra-arterial Infusion

Maximum: ≤0.4 mcg/kg per minute.^{1 3 57 60}

Adults

ED

Initiation and Titration

Intraurethral Suppository

Maximum 2 suppositories within 24 hours.^{98 100 104}

Intracavernosal Injection

Caverject vials and single-use, dual-chambered injection devices: Generally, maximum 60–65 mcg.^{26 32 35 36 41 64 110 b} Administer maximum 2 injections within 24 hours.^{h x}

edex reusable dual-chambered injection device: Dosages >40 mcg not evaluated.^d If a response occurs, allow >1 day interval between doses.^d

Maintenance (Self-administration)

Intraurethral Suppository

Maximum 2 urethral suppositories within a 24-hour period.^{98 100 104}

Intracavernosal Injection

Maximum frequency ≤3 injections weekly with ≥1 day elapsing between each dose.^{34 101 110 b z}

Cautions for Alprostadil (Systemic, Local)

Contraindications

• Intraurethral suppository or intracavernosal injection: Conditions predisposing to priapism (e.g., sickle cell anemia or trait, multiple myeloma, leukemia, thrombocythemia, polycythemia, propensity to develop venous thrombosis, hyperviscosity syndrome).^{8 19 32 64 76 89 97 98 100 b d}

• Intraurethral suppository or intracavernosal injection: Anatomic deformation of penis (e.g., angulation, cavernosal fibrosis, Peyronie’s disease).^{8 19 32 64 76 89 97 98 100 b d}

• Intraurethral suppository or intracavernosal injection: Men for whom sexual activity is inadvisable (e.g., underlying cardiovascular status).^{8 19 32 64 76 89 97 98 100 b h y}

• Intraurethral suppository or intracavernosal injection: Women and children, including neonates.^{d h}

• Intraurethral suppository or intracavernosal injection: Use with penile implants.^{101 b d}

• Intraurethral suppository: Certain GU tract disorders (e.g., urethral stricture or obstruction, balanitis, acute or chronic urethritis, severe hypospadias and curvature, anuria).^{97 98 99 100 105}

• Intraurethral suppository: Use with indwelling urethral catheter.^{97 98 99 100 105}

• Intraurethral suppository: Unprotected sexual intercourse with pregnant women.^{98 100 104}

• Known hypersensitivity to alprostadil or other prostaglandins.^{98 d}

Warnings/Precautions

Warnings

Apnea

Risk of respiratory depression and apnea in neonates with congenital heart defects.^{1 3 44 50 53 60} (See Boxed Warning.)

GI Effects

Risk of gastric outlet obstruction secondary to antral hyperplasia in neonates receiving alprostadil injection for arteriosus-dependent congenital heart disease; associated with prolonged therapy (e.g., cumulative dose and duration of therapy).^{1 3 44 47 49 50 52 54 55 58 59 95}

Closely monitor neonates receiving recommended dosages for >120 hours for evidence of antral hyperplasia and gastric outlet obstruction.^{1 59} During prolonged therapy, carefully weigh possible risk of gastric outlet obstruction against potential benefits.^{1 3 44 47 49 50 52 54 55 58 59 95}

Priapism

Possible prolonged erection (persisting for 4–6 hours) or priapism (erection persisting for >6 hours).^{98 112 b d}

May result in penile tissue damage and permanent loss of potency if not treated immediately^{110 d r} (e.g., aspiration of cavernosal blood, intracavernosal injection of an α-adrenergic agonist or dopamine).^{6 7 8 11 12 19 20 23 46 67 83 89 98 113 b}

Minimize risk of prolonged erection by slowly titrating to lowest possible effective dosage.^{110 b d} Consider decreased dosage or discontinuance in patients who develop priapism or prolonged erection.⁹⁸ (See General: ED, under Dosage and Administration.)

Cardiovascular and Cerebrovascular Effects

Risk of symptomatic hypotension and syncope in patients using intraurethral alprostadil;^{110 d} monitor patients during dosage initiation and titration for manifestations of such effects.^{98 100}

Hypotension and/or dizziness reported following intracavernosal administration; may result from increased peripheral blood levels of prostaglandin E₁, especially in patients with significant corpora cavernosa venous leakage.^{110 d}

Possible hypotension and bradycardia in neonates receiving IV or intra-arterial therapy.^{1 3 50} If bradycardia occurs, discontinue infusion and institute appropriate therapy;^{1 50} (See Dosage: Pediatric Patients under Dosage and Administration) if hypotension occurs, reduce infusion rate and institute appropriate therapy, if necessary.^{1 3 50} (See IV and Intra-arterial Infusion: Rate of Administration under Dosage and Administration.)

Morphologic changes in ductal and pulmonary arteries observed in infants receiving short- or long-term IV or intra-arterial therapy at usual recommended dosages.

General Precautions

Respiratory Distress Syndrome

Do not use in neonates with respiratory distress syndrome;^{1 4 42 49 64} closure of ductus arteriosus is necessary to prevent overload of pulmonary circulation in such neonates.^{4 42 49 55}

Prior to initiating therapy in neonates, make a differential diagnosis between neonatal respiratory distress syndrome (hyaline membrane disease) and cyanotic heart disease (restricted pulmonary blood flow).¹ If full diagnostic facilities not readily available, use cyanosis (evidenced by PO₂ <40 mm Hg) and radiographic evidence of restricted pulmonary blood flow as indicators of cyanotic heart disease.¹

GU Effects

Penile fibrosis, including Peyronie’s disease, reported following intracavernosal administration.^{110 b d}

Examine patients (e.g., every 3 months) for any changes in penis and assess therapeutic benefit.^{34 41 110 b d} Discontinue therapy in any patient who develops penile angulation, cavernosal fibrosis, or Peyronie’s disease during therapy.^{89 110 b d}

Assessment of Patients with Erectile Dysfunction

Thorough medical history and physical examination recommended to diagnose erectile dysfunction, determine potential underlying causes, exclude potentially reversible or treatable causes, identify underlying disorders that might preclude use, and identify appropriate treatment.^{65 110 b d l}

Examine cardiac fitness of patient prior to treatment initiation, particularly in patients with underlying cardiovascular disease.^{l v y}

Sexual Preference

No experience with use in homosexual men or for sexual activities other than vaginal intercourse.^l

Concomitant Therapy

Safety and efficacy of combination therapy with other treatments for erectile dysfunction not established; combined use not recommended by manufacturer.^{64 101 110 b d}

Increased propensity for bleeding with intracavernosal use in patients receiving concurrent anticoagulants (e.g., heparin, warfarin).^{b d h}

Risk of urethral abrasion resulting in minor bleeding or spotting with improper intraurethral use, particularly in patients receiving anticoagulant therapy.^l

Musculoskeletal Effects

Risk of cortical hyperostosis of long bones associated with prolonged IV or intra-arterial therapy in neonates and infants.^{1 3 44 47 49 50 52 54 55 58 59 95} Cortical hyperostosis regresses with therapy withdrawal; carefully weigh possible risk of cortical hyperostosis of long bones against potential benefits.^{1 3 44 47 49 50 52 54 55 58 59 95}

Hematologic Effects

Bleeding reported rarely following IV or intra-arterial infusion; carefully weigh risk to benefit of therapy in neonates with bleeding disorders.^{1 42 44 50 64}

Risk of urethral abrasion resulting in minor bleeding or spotting with improper use of intraurethral suppository.⁹⁸

Risk of hematologic complications (e.g., intracorporeal hematoma, ecchymosis, hemorrhage at the site of injection) with intracavernosal therapy, especially in patients receiving concomitant anticoagulant therapy.^{7 22 25 67 71 83 89 101 111 e r} If bleeding continues or recurs after applying pressure to injection site, abstain from intercourse.^r

Specific Populations

Pregnancy

Category C.^l Not indicated for use in women.^{b d h l}

Intraurethral suppository: Embryotoxic in animals; use condom during sexual intercourse with pregnant woman.^{98 100 104}

Lactation

Not indicated in women.^{b d h l}

Pediatric Use

Intracavernosal injections or intraurethral suppository not indicated for use in children.^{b d h l}

Safety and efficacy of IV or intra-arterial infusion established in infants and neonates.

Geriatric Use

No substantial differences in safety and efficacy relative to younger adults, but decreased sensitivity (e.g., increased dosage requirements) cannot be ruled out.^{b h z}

Common Adverse Effects

IV or intra-arterial infusion: Apnea, fever, seizures, flushing, bradycardia, hypotension, tachycardia.

Intraurethral suppository: Penile or testicular pain,⁹⁸ urethral burning,^l urethral bleeding and/or spotting,^{98 100} minor urethral abrasions.^{98 100}

Intracavernosal injection: Penile pain,^b prolonged erection,^{101 b} penile fibrosis,^b injection site hematoma.^b

Drug Interactions

Specific Drugs

Alprostadil (Systemic, Local) Pharmacokinetics

Absorption

Bioavailability

Absolute bioavailability about 98% following intracavernosal injection.^d

Approximately 80% absorbed ≤10 minutes following intraurethral administration.^l

Onset

Erection usually occurs within 2–25 minutes after intracavernosal injection.^{6 8 10 12 16 17 19 21 23 24 27 28 34 35 36 37 45 46 62 65 67 69 98 101 b d h}

Erection usually occurs within 5–10 minutes after intraurethral administration.^{98 101}

Duration

Erection may persist approximately 1 hour up to several hours following intracavernosal injection.^{6 8 10 12 16 17 19 21 23 24 27 28 34 35 36 37 45 46 62 65 67 69 d h z}

Erection may persist approximately 30–60 minutes following intraurethral administration.⁹⁸

Special Populations

In patients with hepatic impairment receiving alprostadil IV infusion, increased peak blood concentrations of drug and metabolites compared with healthy individuals.^d

In patients with renal impairment receiving alprostadil IV infusion, decreased peak blood concentrations of drug and increased peak blood concentrations of metabolites compared with healthy individuals.^d

Distribution

Extent

Following intraurethral administration, distributed from mucosal cells of urethra into corpus spongiosum, corpus cavernosum, and pelvic venous circulation.^{97 98 105} Some drug may distribute from corpus spongiosum directly into pelvic venous circulation bypassing corpus cavernosum.^{105 l}

Following intracavernosal administration, no appreciable binding to erythrocytes or WBCs.^{b h}

Plasma Protein Binding

93%.^d

Elimination

Metabolism

Following intracavernosal or intraurethral administration, principally metabolized locally in corpus cavernosum or urethra via oxidation and reduction.^{105 l z} Portion of drug released into systemic circulation and metabolized by lungs.^{d h l z}

Following systemic administration, rapidly and extensively metabolized principally in the lungs via β- and ω-oxidation.^{1 20 22 24 26 27 28 34 44 54 55 67 94 d h z}

Elimination Route

Following IV administration, excreted principally in urine (88–90%) as metabolites and in feces (10–12%). ^{b d h l z}

Half-life

Intraurethral suppository: 30 seconds to 10 minutes, depending on body compartment measured and physiologic status of individual.^l

Intracavernosal injection: 9–11 minutes in healthy individuals.^d

Special Populations

In patients with hepatic or renal impairment receiving alprostadil IV infusion, terminal half-lives of drug and metabolites unaffected.^d

Stability

Storage

Parenteral

Powder for Injection

edex: 25°C (may be exposed to 15–30°C).^{d r} Do not freeze; protect from excessive heat.^r Use reconstituted solution immediately; discard unused solution.^{d r}

Caverject With 20-mcg vials, ≤25°C.^{b e} Do not freeze; protect from excessive heat.^e With 40 mcg vials, 2–8°C until dispensed;^b thereafter ≤25°C for 3 months or expiration date, whichever comes first.^{b e} Do not freeze; protect from excessive heat.^e Use reconstituted solutions within 24 hours when stored at ≤25°C; do not refrigerate or freeze.^{b e}

Caverject impulse: 25°C (may be exposed to 15–30°C).¹¹⁰ Do not freeze; protect from excessive heat.ⁱ Use reconstituted solutions within 24 hours when stored at ≤25°C; discard unused solution.^{110 i}

Intraurethral Suppository

Refrigerate at 2–8°C; protect from light and excessive heat (temperatures >30°C).^l Store in unopened foil pouches until use.^{l l} May be stored at <30°C for ≤14 days prior to use.^l

Injection Concentrate for Infusion

2–8°C.¹

Discard unused diluted solutions after 24 hours.^{1 44}

Actions

Ductus Arteriosus-dependent Congenital Heart Disease

• Dilates constricted ductus arteriosus in neonates with cyanotic congenital heart disease.^{1 3 43 56 58}

• In neonates with restricted pulmonary blood flow, increases pulmonary blood flow through combined maintenance of patency of ductus arteriosus and dilation of pulmonary vascular bed.^{43 44 55 56 58 60 70} Temporarily increases arterial oxygen partial pressure (PaO₂) and oxygen saturation.^{1 3 43 56 58}

• In neonates with restricted systemic blood flow, prevents or corrects acidemia and increases cardiac output, systemic BP, femoral pulse volume, and renal blood flow and function (urine production).^{1 3 29 43 44 51 56 57 60}

• In neonates with coarctation of aorta, decreases gradient of descending to ascending aortic BP.^{1 3 29 43 44 51 56 57 60}

• In neonates with interruption of aortic arch, decreases gradient of pulmonary artery to descending aortic BP.^{1 3 29 43 44 51 56 57 60}

Erectile Dysfunction

• Interacts with specific membrane-bound receptors that stimulate adenylate cyclase and elevates intracellular concentrations of cyclic adenosine-3’,5’-monophosphate (AMP), leading to activation of protein kinase and resultant smooth muscle relaxation.^{6 8 12 97 z}

• Induces erection by relaxing trabecular smooth muscle and dilating cavernosal arteries and their branches (i.e., the helicine arterioles of the penis).^{2 11 15 19 20 21 24 27 28 34 46 64 65 71 98 101 102}

• Increases arterial inflow velocity and venous outflow resistance resulting in penile blood engorgement and erection.^{15 18 85 98 110}

• Drug may enhance actions of nonadrenergic, noncholinergic, vasodilatory neurotransmitters (e.g., nitric oxide, neuropeptide Y, calcitonin gene-related peptide, vasoactive intestinal polypeptide).^{6 8 12 20 21 33 46 62}

Advice to Patients

Erectile Dysfunction

• Importance of providing patient a copy of manufacturer’s patient information.^{5 83 98 100 101 112}

• Importance of informing clinician of history of syncope prior to treatment initiation with intraurethral suppository.¹⁰⁰

• Importance of understanding proper storage, preparation, and administration techniques, including precautions and proper disposal of used needles, injection devices, syringes and unused reconstituted drug solutions.^{5 10 22 34 67 69 71 83 98 100 101 110 112 d}

• Importance of not storing vials or injection devices in checked airline baggage (storage in passenger compartment permitted) or closed automobile.^{64 111 e r} Importance of avoiding freezing or exposure to temperatures >25°C.^{64 111 e}

• Importance of contacting a clinician if needle breaks during penile injection.^{e i r}

• Potential for transmission of sexually transmitted diseases or blood-borne diseases and need to use protective measures to guard against such transmission.¹¹⁰

• With intraurethral suppository, importance of using a condom when engaging in sexual intercourse with a pregnant woman.^{98 100 104}

• Importance of contacting clinician regularly for assessment of therapeutic benefit, need for possible dosage adjustment, and of potential adverse effects.^{34 41 89 101 110}

• Importance of seeking immediate medical attention if erection persists >4 hours.^{34 78 79 89 98 100 110 112 113}

• Importance of informing clinician of penile pain that develops or intensifies during intracavernosal therapy. ¹¹⁰

• Importance of informing clinician of nodules or hard areas in penis, any sign of infection (e.g., penile erythema, swelling, tenderness) or unusual curvature.¹¹⁰

• Possible dizziness, hypotension, or syncope with intraurethral suppository; use caution when driving or operating machinery.⁹⁸ Importance of lying down and immediately raising legs if light-headed feeling, dizziness, feeling of faintness, or rapid pulse experienced.¹⁰⁰ Importance of informing a clinician if such symptoms persist.¹⁰⁰

• Importance of informing clinician of existing or contemplated concomitant therapy (e.g., agents interfering with blood clotting, antihypertensive agents), including prescription and OTC drugs, as well as any concomitant illnesses (e.g., conditions interfering with blood clotting).^{98 110 d r}

• Importance of informing patients of other important precautionary information.^d

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

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