Skip to main content

Vardenafil (Monograph)

Brand name: Levitra
Drug class: Calcium-Channel Blocking Agents
Chemical name: 1-[[3-(3,4-Dihydro-5-methyl-4-oxo-7-propylimidazo[5,1-f]-as-triazin-2-yl)-4-ethoxyphenyl]sulfonyl]-4-ethylpiperazine
Molecular formula: C23H32N6O4S
CAS number: 224785-90-4

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

Introduction

Vasodilating agent; a selective phosphodiesterase (PDE) inhibitor.1

Uses for Vardenafil

Erectile Dysfunction (ED)

To facilitate attainment of a sexually functional erection in men with ED (impotence).1

Some experts recommend a selective PDE type 5 inhibitor as first-line therapy for ED unless contraindicated.40 Evidence currently insufficient to support superiority of one selective PDE type 5 inhibitor over another.40

Effective for ED only in the presence of adequate sexual stimulation.1

Vardenafil Dosage and Administration

Administration

Oral Administration

Administer orally, no more than once daily, without regard to meals.1 3

Administer approximately 1 hour before anticipated sexual activity.1

Dosage

Available as vardenafil hydrochloride; dosage expressed in terms of vardenafil.1

Adults

ED
Oral

Initially, 10 mg.1 Depending on effectiveness and tolerance, increase dosage to a maximum of 20 mg or decrease to 5 mg. Administer no more frequently than once daily.1

Prescribing Limits

Adults

ED
Oral

Maximum 20 mg daily.1

Special Populations

Hepatic Impairment

Oral

In patients with moderate hepatic impairment (Child-Pugh class B), decrease initial dosage to 5 mg; maximum dosage is 10 mg once daily.1

Do not use in patients with severe hepatic impairment (Child-Pugh class C).1

Renal Impairment

Oral

Dosage adjustments not required in patients with Clcr of 30–80 mL/minute.1

Do not use in patients requiring renal dialysis.1

Geriatric Patients

Oral

Reduce initial dose to 5 mg given no more frequently than once daily in men ≥65 years of age.1 26

Patients Receiving Concomitant Potent or Moderate CYP3A4 Inhibitors

Oral

Reduction in initial vardenafil dose required when given concomitantly with certain drugs that are potent or moderate CYP3A4 inhibitors.1 (See Specific Drugs or Foods under Interactions.)

Patients Receiving Concomitant α-Adrenergic Blocking Agents

Oral

In patients on stable α-adrenergic blocker therapy, initiate vardenafil at lowest recommended starting dose.1 Consider a time interval between dosing of vardenafil and concomitant α-adrenergic blocker.1 (See Specific Drugs or Foods under Interactions.)

Cautions for Vardenafil

Contraindications

Warnings/Precautions

Sensitivity Reactions

Allergic reactions, including allergic edema and angioedema, reported.1

Patient Assessment

Thorough medical history and physical examination recommended to diagnose ED, determine potential underlying causes, and identify appropriate treatment.1 5

Review of the patient’s current drug regimens recommended to detect possible drug-induced ED.5

Cardiovascular Effects

Serious, potentially fatal cardiovascular events reported rarely.1 5 6

Potentiation of hypotensive effect with organic nitrates or nitric oxide donors (see Specific Drugs or Foods under Interactions) may result in life-threatening hypotension and/or hemodynamic compromise; concomitant use of such drugs with vardenafil contraindicated.1 28 (See Contraindications under Cautions.)

Sexual activity associated with a degree of cardiac risk; risk greater in men with pre-existing cardiovascular disease.1 5 6 28 Assess cardiovascular status of patient before initiating vardenafil therapy.1 28 Therapy for ED not recommended for men in whom sexual activity is inadvisable because of their underlying cardiovascular status.1 28

Safety and efficacy not established and use not recommended pending additional information in patients with unstable angina; hypotension (resting SBP <90 mm Hg) or uncontrolled hypertension (>170/110 mm Hg SBP/DBP); recent (within 6 months) stroke, life-threatening arrhythmia, or MI; or severe heart failure.1 4 7 8 26

Possible hypotension; consider whether patients with underlying cardiovascular disease could be affected adversely by vardenafil’s vasodilatory activity.1 Risk of an undesired hypotensive or vasodilatory response is of particular concern in patients with left-ventricular outflow obstruction (e.g., aortic stenosis, idiopathic hypertrophic subaortic stenosis).1 6

May prolong QT interval; consider such potential effects when prescribing vardenafil to patients with known history of QT prolongation or in those taking drugs known to prolong the QT interval.1 Avoid use of vardenafil in patients with congenital prolongation of the QT interval and in those receiving class IA or class III antiarrhythmic agents.1 (See Specific Drugs or Foods under Interactions.)

Concomitant Use with Potent or Moderate CYP3A4 Inhibitors

Increased plasma vardenafil concentrations with concomitant administration of potent (e.g., ritonavir, indinavir, ketoconazole) or moderate (e.g., erythromycin) CYP3A4 inhibitors; vardenafil dosage reduction recommended.1 29 30 31 33 34 47 48 49 50 51 (See Specific Drugs or Foods under Interactions.)

Data on specific interactions lacking, but increased exposure to vardenafil likely with other concomitant CYP3A4 inhibitors, including grapefruit juice.1

Safety of long-term concomitant use of vardenafil and HIV protease inhibitors not established.1

Priapism

Possible prolonged erections (>4 hours in duration) and priapism (painful erection >6 hours).1

May result in penile tissue damage and permanent loss of potency if priapism is not treated immediately.1 Use with caution in patients with conditions predisposing to priapism (e.g., sickle cell anemia, multiple myeloma, leukemia) and in patients with anatomical deformation of the penis (e.g., angulation, cavernosal fibrosis, Peyronie’s disease).1

Ocular Effects

Nonarteritic anterior ischemic optic neuropathy (NAION) reported rarely during postmarketing experience in temporal association with use of all PDE type 5 inhibitors.1 Potential increased risk of NAION recurrence in patients who have already experienced NAION.1 Use with caution in such patients and only if anticipated benefits outweigh risks.1 If sudden vision loss or decreased vision occurs, discontinue vardenafil and contact clinician immediately.1 28

Visual disturbances (e.g., abnormal, dim, or blurred vision; changes in color vision [e.g., chromatopsia]) reported.1 4

Not studied in patients with hereditary degenerative retinal disorders, including those with retinitis pigmentosa.1 Use not recommended in such patients until further information available.1

Otic Effects

Risk of sudden decrease or loss of hearing with all PDE type 5 inhibitors, in some cases accompanied by vestibular toxicity (e.g., tinnitus, vertigo, dizziness).1 28 41 44 Such effects reported rarely in clinical trials and during postmarketing experience.1 41 44 45 A causal relationship not established; however, a strong temporal association observed.1 28 41 44

Discontinue drug and contact clinician immediately if sudden decrease or loss of hearing occurs.1 28 44

Concomitant Administration with α-Adrenergic Blocking Agents

Use with caution in patients receiving α-adrenergic blocking agents; possible potentiation of hypotensive effects due to additive vasodilatory action.1 In some cases, dose adjustments are necessary; in other cases, concomitant administration not recommended.1 (See Specific Drugs or Foods under Interactions.) Safety of concomitant therapy also may be affected by intravascular volume depletion and use of other antihypertensive agents.1

Concomitant Use with Other PDE Type 5 Inhibitors or ED Therapies

Safety and efficacy of combined use with other PDE type 5 inhibitors or other treatments for ED not established; do not use vardenafil concomitantly with other PDE type 5 inhibitors.1

Hematologic Effects

No prolongation of bleeding time with vardenafil dosages ≤20 mg.1

However, data lacking on use in patients with bleeding disorders or active peptic ulcers;1 4 8 therefore, careful risk/benefit assessment is necessary before use in such patients.1 4 8

Specific Populations

Pregnancy

Category B.1 Not indicated for use in women.1

Lactation

Not indicated for use in women.1

Pediatric Use

Not indicated for use in pediatric patients; clinical trials not conducted in these patients.1

Geriatric Use

Safety and efficacy in males ≥65 years of age similar to that in younger males.1 Increased plasma vardenafil concentrations in men ≥65 years of age compared to that in younger males; therefore consider lower initial dosage.1 (See Geriatric Patients under Dosage and Administration.)

Hepatic Impairment

Decreased clearance in patients with mild (Child-Pugh class A) or moderate (Child-Pugh class B) hepatic impairment.1 (See Hepatic Impairment under Dosage and Administration.) Do not use in patients with severe hepatic impairment (Child-Pugh class C).1

Renal Impairment

Clearance decreased in patients with Clcr 30–80 mL/minute.1 (See Renal Impairment under Dosage and Administration.) Do not use in patients with end-stage renal disease requiring dialysis.1

Common Adverse Effects

Headache,1 2 7 8 flushing, 1 2 7 8 rhinitis,1 2 8 dyspepsia,1 2 7 sinusitis,1 flu syndrome,1 dizziness,1 increased creatinine kinase,1 nausea,1 back pain.1

Drug Interactions

Metabolized principally by CYP3A4; CYP2C and CYP3A5 appear to play a minor role.1

Drugs Affecting Hepatic Microsomal Enzymes

Inhibitors of CYP3A4: Potential pharmacokinetic interaction (increased plasma vardenafil concentrations).1

Specific Drugs or Foods

Drug

Interaction

Comments

α-Adrenergic blocking agents (e.g., alfuzosin, tamsulosin, terazosin)

Possible symptomatic hypotension 1

In patients on stable α-adrenergic blocker therapy, initiate vardenafil at lowest recommended starting dose1

In patients on optimized dose of vardenafil, initiate α-adrenergic blocker at lowest dose1

Alcohol

No potentiation of hypotensive effect reported1

Antacids (aluminum hydroxide and magnesium hydroxide)

Pharmacokinetic interaction unlikely1

Antiarrhythmic agents, class 1A (e.g., procainamide, quinidine) or class III (e.g., amiodarone, sotalol)

Possible prolongation of the QTc interval1

Avoid concomitant use1

Antihypertensive agents

Possible additive hypotensive effects

Antiretroviral agents, HIV protease inhibitors

Possible increased vardenafil concentrations and increased risk of vardenafil-associated adverse effects (e.g., hypotension, visual changes, prolonged erection)1 29 31 33

Decreased indinavir and ritonavir concentrations1 29 31 33

Ritonavir or lopinavir: Do not exceed a single vardenafil dose of 2.5 mg in 72 hours;1 29 no change in ritonavir dosage needed29

Ritonavir in combination with indinavir, atazanavir, saquinavir, fosamprenavir, or nelfinavir: Do not exceed a vardenafil dosage of 2.5 mg in 72 hours29 33

Nelfinavir, indinavir, amprenavir, saquinavir, fosamprenavir, or atazanavir: Use initial vardenafil dosage of 2.5 mg and do not exceed a single dose of 2.5 mg in 24 hours1 29 30 31 33

Monitor closely 29 31 33 34

Antiretroviral agents, nonnucleoside reverse transcriptase inhibitors

Possible increased vardenafil concentrations and increased risk of vardenafil-associated adverse effects (e.g., hypotension, visual changes, prolonged erection)29

Delavirdine: Use initial vardenafil dosage of 2.5 mg; do not exceed 2.5 mg once in 24 hours29

Aspirin

No increase in bleeding time reported1

Cimetidine

Pharmacokinetic interaction unlikely1

Digoxin

Pharmacokinetic interaction unlikely1

Erythromycin

Increased AUC and peak plasma concentrations of vardenafil1

Reduce initial vardenafil dosage to 5 mg in patients receiving erythromycin; do not exceed 5 mg of vardenafil once in 24 hours1

Glyburide

Pharmacokinetic interaction unlikely1

Grapefruit juice

Potential increase in vardenafil exposure1

Guanylate cyclase stimulators (e.g., riociguat)

PDE type 5 inhibitors may potentiate hypotensive effects of guanylate cyclase stimulators1

Concomitant use contraindicated1

Inhaled nitrites (e.g., amyl or butyl nitrite)

Potentiation of hypotensive effect28

Concomitant use contraindicated28

Itraconazole

Possible increased vardenafil concentrations1

Reduce initial vardenafil dosage to 2.5 mg in patients receiving itraconazole 400 mg daily; do not exceed 2.5 mg of vardenafil once in 24 hours1

Reduce initial vardenafil dosage to 5 mg in patients receiving itraconazole 200 mg daily; do not exceed 5 mg of vardenafil once in 24 hours1

Ketoconazole

Increased vardenafil concentrations 1

Reduce initial vardenafil dosage to 2.5 mg in patients in patients receiving ketoconazole 400 mg daily; do not exceed 2.5 mg of vardenafil once in 24 hours1

Reduce initial vardenafil dosage to 5 mg in patients receiving ketoconazole 200 mg daily; do not exceed 5 mg of vardenafil once in 24 hours1

Nifedipine

Possible additive hypotensive effect1

Nitrates and nitric acid donors

Potentiation of vasodilatory effects; potentially life-threatening hypotension and/or hemodynamic compromise can result1

Concomitant use contraindicated1 28

Ranitidine

Pharmacokinetic interaction unlikely

Warfarin

Pharmacokinetic and pharmacodynamic interaction unlikely1

Vardenafil Pharmacokinetics

Absorption

Bioavailability

Rapidly absorbed following oral administration; peak concentrations usually attained within 0.5–2 hours.1

Absolute bioavailability is approximately 15%.1

Food

Administration with a high-fat meal reduces the peak plasma concentrations by 18–50%.1 3

Distribution

Extent

Extensively distributed into tissues.1

Plasma Protein Binding

Approximately 95% for the drug and major metabolite.1

Elimination

Metabolism

Metabolized in the liver to active metabolite(s) principally via CYP3A4, with minor contributions from CYP3A5 and CYP2C.1

Elimination Route

Excreted as metabolites principally in the feces (91–95%) and to a lesser extent in urine (2–6%).1

Half-life

Terminal half-life 4–5 hours for drug and major metabolite.1

Special Populations

Clearance reduced in men ≥65 years of age, resulting in an increase in AUC and peak plasma concentrations compared with younger males.1

Clearance reduced in patients with moderate (Clcr of 30–50 mL/minute) or severe (Clcr <30 ml/minute) renal impairment, resulting in an increase in AUC compared with patients with normal renal function.1

Clearance reduced in patients with mild (Child-Pugh class A) or moderate (Child-Pugh class B) hepatic impairment, resulting in an increase in AUC and peak plasma concentrations compared with healthy adults.1

Stability

Storage

Oral

Tablets

25°C (may be exposed to 15–30°C).1

Actions

Advice to Patients

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.

Vardenafil Hydrochloride

Routes

Dosage Forms

Strengths

Brand Names

Manufacturer

Oral

Tablets, film-coated

2.5 mg (of vardenafil)

Levitra

GlaxoSmithKline

5 mg (of vardenafil)

Levitra

GlaxoSmithKline

10 mg (of vardenafil)

Levitra

GlaxoSmithKline

20 mg (of vardenafil)

Levitra

GlaxoSmithKline

AHFS DI Essentials™. © Copyright 2024, Selected Revisions April 10, 2024. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

References

1. GlaxoSmithKline. Levitra (vardenafil hydrochloride) tablets prescribing information. Research Triangle Park, NC; 2015 Sep.

2. Coleman CI, Carabino JM, Vergara CM. Vardenafil: an oral selective phosphodiesterase 5 inhibitor for the treatment of erectile dysfunction. Formulary. 2003; 38:131-148.

3. Rajagopalan P, Mazzu A, Xia C et al. Effect of high-fat breakfast and moderate-fat evening meal on the pharmacokinetics of vardenafil, an oral phosphodiesterase-5 inhibitor for the treatment of erectile dysfunction. J Clin Pharmacol. 2003; 43(3):260-7. http://www.ncbi.nlm.nih.gov/pubmed/12638394?dopt=AbstractPlus

4. Brock G, Nehra A, Lipshultz LI et al. Safety and efficacy of vardenafil for the treatment of men with erectile dysfunction after radical retropubic prostatectomy. J Urol. 2003; 170(4 Pt 1):1278-83. http://www.ncbi.nlm.nih.gov/pubmed/14501741?dopt=AbstractPlus

5. Jackson G, Betteridge J, Dean J et al. A systematic approach to erectile dysfunction in the cardiovascular patient: a Consensus Statement--update 2002. Int J Clin Pract. 2002; 56(9):663-71. http://www.ncbi.nlm.nih.gov/pubmed/12469980?dopt=AbstractPlus

6. Cheitkin MD, Hutter AM, Brindis RG for the American College or Cardiology and American Heart Association. Technology and Practice Executive Committee [duplicate publication of Cheitkin MD, Hutter AM, Brindis RG for the American College or Cardiology and American Heart Association. ACC/AHA expert consensus document: use of sildenafil (viagra) in patients with cardiovascular disease. American College of Cardiology/American Heart Association. J Am Coll Cardiol. 1999; 33:273-82.

7. Hellstrom WJ, Gittelman M, Karlin G et al. Sustained efficacy and tolerability of vardenafil, a highly potent selective phosphodiesterase type 5 inhibitor, in men with erectile dysfunction: results of a randomized, double-blind, 26-week placebo-controlled pivotal trial. Urology. 2003; 61(4 Suppl 1):8-14. http://www.ncbi.nlm.nih.gov/pubmed/12657355?dopt=AbstractPlus

8. Goldstein I, Young JM, Fischer J et al. Vardenafil, a new phosphodiesterase type 5 inhibitor, in the treatment of erectile dysfunction in men with diabetes: a multicenter double-blind placebo-controlled fixed-dose study. Diabetes Care. 2003; 26(3):777-83. http://www.ncbi.nlm.nih.gov/pubmed/12610037?dopt=AbstractPlus

9. National Institutes of Health Office of Medical Applications of Research. Consensus Conference: impotence. JAMA. 1993; 270:83-90. http://www.ncbi.nlm.nih.gov/pubmed/8510302?dopt=AbstractPlus

10. Pfizer Inc, New York, NY: Personal communication on sildenafil.

11. Reviewers’ comments on sildenafil (personal observations).

12. The Process of Care Consensus Panel. Position paper: the process of care model for evaluation and treatment of erectile dysfunction. Int J Impotence Res. 1999; 11:59-70.

13. Palmer BF. Sexual dysfunction in uremia. J Am Soc Nephrol. 1999; 10:1381-8. http://www.ncbi.nlm.nih.gov/pubmed/10361878?dopt=AbstractPlus

14. Guay AT, Nankin AR et al. AACE clinical practice guidelines for the evaluation and treatment of male sexual dysfunction. From American Association of Clinical Endocrinologists web site http://www.aace.com/pub/pdf/guidelines/sexdysguid.pdf

15. Whitehead ED, Klyde BJ, Zussman S et al. Treatment alternatives for impotence. Postgrad Med. 1990; 88:139-52. http://www.ncbi.nlm.nih.gov/pubmed/2199954?dopt=AbstractPlus

16. Gerber GS, Levine LA. Pharmacological erection program using prostaglandin E1. J Urol. 1991; 146:786-9. http://www.ncbi.nlm.nih.gov/pubmed/1875494?dopt=AbstractPlus

17. Porst H. Editorial comments on the process of care model for evaluation and treatment of erectile dysfunction. Int J Impotence Res. 1999; 11: 72-3.

18. Sarramon JP. Editorial comments on the process of care model for evaluation and treatment of erectile dysfunction. Int J Impotence Res. 1999; 11:73.

19. Vermeuler A. Editorial comments on the process of care model for evaluation and treatment of erectile dysfunction. Int J Impotence Res. 1999; 11:74.

20. Sohn MHH. Editorial comments on the process of care model for evaluation and treatment of erectile dysfunction. Int J Impotence Res. 1999; 11:72.

21. Sefetl AD. Phosphodiesterase type 5 inhibitor differentiation based on selectivity, pharmacokinetic, and efficacy profiles. Clin Cardiol. 2004; 27(Suppl. 1):I-14-9.

22. Padma-Nathan H. A new era in the treatment of erectile dysfunction. Am J Cardiol. 1999; 84:18-23N. http://www.ncbi.nlm.nih.gov/pubmed/10404845?dopt=AbstractPlus

23. Wespes E, Amar E, Hatzichtistou D et al. Guidelines on reactile dysfunction. Arnhem: European Association of Urology, 2004 Mar. Accessed 2004 Aug. http://www.uroweb.org/professional-resources/guidelines

24. Pfizer Inc. Viagra (sildenafil citrate) prescribing information. New York, NY; 2014 Mar.

25. Lilly. Cialis (tadalafil) tablets prescribing information. Indianapolis, IN; 2014 Apr.

26. Schering-Plough, Kenilworth, NJ. Personal communication.

27. Crowe SM, Streetman DS. Vardenafil treatment for erectile dysfunction. Ann Pharmacother. 2004; 38:77-85. http://www.ncbi.nlm.nih.gov/pubmed/14742800?dopt=AbstractPlus

28. GlaxoSmithKline. Levitra (vardenafil hydrochloride) tablets patient information. Research Triangle Park, NC; 2015 Sep.

29. Panel on Clinical Practices for Treatment of HIV infection of the Department of Health and Human Services (DHHS). Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents (Apr 7, 2005). From the US Department of Health and Human Services HIV/AIDS Information Services (AIDSinfo) website. http://www.aidsinfo.nih.gov

30. Merck & Company Inc. Crixivan (indinavir sulfate) capsules prescribing information. West Point, PA; 2004 May.

31. Bristol-Myers Squibb. Reyataz (atazanavir sulfate) prescribing information. Princeton, NJ; 2004 Jul.

33. GlaxoSmithKline. Lexiva (fosamprenavir calcium) tablets prescribing information. Research Triangle Park, NC; 2004 May.

34. Roche Laboratories. Invirase (saquinavir mesylate) capsules prescribing information. Nutley, NJ; 2004 Dec.

35. Goldstein I, Lue TF, Padma-Nathan H et al. Oral sildenafil in the treatment of erectile dysfunction. N Engl J Med. 1998; 338:1397-404. http://www.ncbi.nlm.nih.gov/pubmed/9580646?dopt=AbstractPlus

36. Smith KM, Romanelli F. Recreational use and misuse of phosphodiesterase 5 inhibitors. J Am Pharm Assoc (Wash DC). 2005; 45(Jan-Feb):63-72.

37. Center for Drug Evaluation and Research, Food and Drug Administration. FDA alert for healthcare professionals: vardenafil. 2005 Jul. From the FDA website. http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm126249.htm

38. Food and Drug Administration. FDA statement: FDA updates labeling for viagra, cialis, levitra for rare postmarketing reports of eye problems. 2005 Jul. 8. From FDA website. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/2005/ucm108458.htm

40. Erectile Dysfunction Guideline Update Panel, American Urological Association Education and Research. Management of erectile dysfunction: An update. 2005. Available from website. http://www.auanet.org

41. Food and Drug Administration. Medwatch Safety-related drug labeling changes: Viagra (sildenafil), Cialis (tadalafil), Levitra (vardenafil) and Revatio (sildanafil) tablets [October 18 2007]. From FDA Website. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/2007/ucm109012.htm

44. Food and Drug Administration, Center for Drug Evaluation and Research. Questions and answers about Viagra, Levitra, Cialis, and Revatio: Possible sudden hearing loss. From FDA Website. http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm106525.htm

45. Mukherjee B, Shivakumar T. A case of sensorineural deafness following ingestion of sildenafil. J Laryngol Otol. 2007; 121:395-7. http://www.ncbi.nlm.nih.gov/pubmed/17166328?dopt=AbstractPlus

46. Bollinger KL, Lee MS. Recurrent visual field defect and ischemic optic neuropathy associated with tadalafil rechallenge. Arch Ophthalmol. 2005; 123:400-1. http://www.ncbi.nlm.nih.gov/pubmed/15767488?dopt=AbstractPlus

47. Abbott Laboratories. Kaletra (lopinavir/ritonavir) oral capsules and solution prescribing information. North Chicago, IL; 2007 Jul.

48. Abbott Laboratories. Norvir (ritonavir) capsules and oral solution prescribing information. North Chicago, Il; 2008 Oct.

49. Tibotec. Prezista (darunavir) tablets prescribing information. Raritan, NJ; 2008 Dec.

50. Agouron. Viracept (nelfinavir) tablets and oral powder prescribing information. La Jolla, CA; 2008 Sep.

51. Boehringer Ingelheim. Aptivus (tipranavir) capsules prescribing information. Ridgefield, CT; 2008 Jun.