Nonarteritic ischemic optic neuropathy developing soon after use of sildenafil (Viagra): a report of seven new cases. Tadalafil associated with anterior ischemic optic neuropathy. 16.Bollinger K, Lee MS.

• Tadalafil belongs to PDE5 inhibitors, aiding blood flow.
• It is sometimes called "female Viagra" in popular media.
• Tadalafil's duration of action is approximately 36 hours.
• Female users should consult healthcare providers before use.
• Tadalafil may interact with other medications like nitrates.
• Existing studies show mixed results on tadalafil’s efficacy in women.
• It may be more effective when combined with therapy.
• Not recommended for women with certain cardiovascular conditions.
• Female use of tadalafil is still experimental and investigational.

Recurrent visual field defect and ischemic optic neuropathy associated with tadalafil rechallenge. Legal Disclaimer: All information presented in this website is intended for informational purposes only and not for the purpose of rendering medical advice. Volume VII, Number 2 March/April 2004 Christina Collins, Pharm.D. Erectile dysfunction (ED) is a common disorder that affects up to 30 million men in the United States alone.1,2 ED is defined as the inability to achieve or maintain a penile erection sufficient for sexual function.3 The prevalence of this disorder increases with age and predominantly affects men over the age of 40.4,5 In addition to age, there are some disease states that predispose men to develop ED, including hypertension, diabetes mellitus, and atherosclerosis. Smoking, excessive alcohol intake, and some medications (e.g., thiazide diuretics, calcium channel blockers, beta-blockers, digoxin, selective serotonin reuptake inhibitors, and tricyclic antidepressants) may also contribute to the development of ED.4,6 ED may be categorized into three types based on the causative factors: organic, psychogenic, and multifactorial.4,6 Organic causes include diabetes, hypertension, spinal cord injuries, and some medications. Depression, psychological stress, relationship problems, and performance anxiety are all of psychogenic origin.5 Multifactorial causes are any combination of the above.

• Tadalafil generally takes about 30-60 minutes to work in women.
• Its effects can last up to 36 hours, providing flexibility.
• It is not a standard treatment but a research tool in women.
• The drug is often compared to sildenafil in studies.
• Women should avoid heavy meals before taking tadalafil.
• Proper hydration may improve its effectiveness.
• Women with hypertension should consult a doctor before use.
• Tadalafil may cause visual disturbances in rare cases.
• Its safety profile in women continues to be studied.

With greater public awareness and discussion of ED, the demand for new and improved treatments has increased tremendously. The phosphodiesterase type 5 (PDE-5) inhibitor sildenafil (Viagra®) has become the drug of choice for treatment of ED since it reached the market in March of 1998.

Cialis Safety for Women: Key Considerations

Tadalafail was evaluated in combination with doxazosin (Cardura®) and resulted in a significant increase in the blood pressure-lowering effect of doxazosin. Similarly to the other agents, tadalafil is also contraindicated with the use of organic nitrates. This is due to sildenafil's convenience and tolerability compared to previous therapies.5 It has been shown to be beneficial in the treatment of organic and psychogenic ED.5,6 Sildenafil does have some disadvantages such as side effects and a relatively short duration of action; consequently, the search for the ideal drug to treat ED has continued. This sustained pursuit has led to the development of two new PDE-5 inhibitors: vardenafil (Levitra®; Bayer Pharmaceuticals Corporation in cooperation with GlaxoSmithKline) was approved by the Food and Drug Administration (FDA) on August 19, 2003, and tadalafil (Cialis; Eli Lilly Corporation) was FDA-approved in November 2003.2 These new agents possess distinguishing characteristics that differentiate themselves from each other and sildenafil. Sildenafil, vardenafil, and tadalafil are all PDE-5 inhibitors indicated for the treatment of ED.

They do not directly cause penile erections, however, they affect the response to sexual stimulation.

Additional information

During sexual stimulation, nitric oxide is produced, which then activates cyclic guanosine monophosphate (cGMP). This results in smooth muscle relaxation and increased blood flow.5 Phosphodiesterases, however, catalyze the breakdown of cGMP to its corresponding monophosphate, GMP. There are several PDE isoenzymes, and PDE-5 is the isoenzyme present in highest concentrations in the smooth muscle of the corpora cavernosum of the penis. The PDE-5 inhibitors, sildenafil, vardenafil, and tadalafil mimic the structure of cGMP and competitively inhibit its breakdown by PDE-5 in the corpus cavernosum and related vessels, leading to increased dilatation and blood flow. This allows the induction of an erection during sexual stimulation.7 Sildenafil, vardenafil, and tadalafil all affect ED through the same basic mechanism of inhibiting PDE-5 but have differing potencies and affinities for each of the 11 PDE isoenzymes.

Table 2.

Vardenafil is the most potent PDE-5 inhibitor, followed by sildenafil and tadalafil.7 However, there is no current evidence that greater drug potency has produced improved clinical efficacy. The affinities vary for the other PDE isoenzymes, and thus may explain the potential differences in their side effect profiles. While sildenafil, vardenafil, and tadalafil are all hepatically metabolized, there are variances in their pharmacokinetic profiles. Sildenafil is approximately 75% metabolized, predominantly by cytochrome P450 (CYP) 3A4 with contribution from CYP 2C9.7,8 Vardenafil is primarily metabolized by CYP 3A4 and secondarily by CYP 3A5 and 2C isoforms.7,9 Tadalafil is also metabolized by CYP 3A4.2,10 With CYP 3A4 being the major enzyme responsible for the metabolism of all three agents, they will potentially have many of the same drug interactions with some possible contributions from the minor enzymatic pathways. Other pharmacokinetic differences include time to maximum concentration and half-life.

Related treatment guides

The slightly faster time to maximum concentration of vardenafil (0.7 hours) compared to sildenafil (0.8 hours) is likely clinically irrelevant, while tadalafil has the slowest onset and may require 2 hours to reach maximum concentration. Tadalafil, however, has the longest half-life (17.5 hours), followed by tadalafil 60mg uk vardenafil (4 hours) and sildenafil (3.7 hours).7-10 These differences will account for variation in dosage timing and duration of effect. The considerably longer duration of effect for tadalafil will likely allow less frequent dosing and greater impulsiveness between partners, but also could potentially prolong adverse effects. There are no comparative trials evaluating sildenafil, vardenafil, and tadalafil; therefore, it is difficult to compare the individual trials available due to differences in study design and methodology. However, all three agents have been proven effective in treating ED in clinical trials based on the Erectile Function domain score of the International Index of Erectile Function, a sexual function questionnaire commonly used throughout the studies. During sexual stimulation, nitric oxide is produced, which then activates cyclic guanosine monophosphate (cGMP).

This results in smooth muscle relaxation and increased blood flow.5 Phosphodiesterases, however, catalyze the breakdown of cGMP to its corresponding monophosphate, GMP. There are several PDE isoenzymes, and PDE-5 is the isoenzyme present in highest concentrations in the smooth muscle of the corpora cavernosum of the penis. The PDE-5 inhibitors, sildenafil, vardenafil, and tadalafil mimic the structure of cGMP and competitively inhibit its breakdown by PDE-5 in the corpus cavernosum and related vessels, leading to increased dilatation and blood flow.

Safety Considerations for Women Using Cialis

Nonarteritic ischemic optic neuropathy developing soon after use of sildenafil (Viagra): a report of seven new cases. Tadalafil associated with anterior ischemic optic neuropathy. 16.Bollinger K, Lee MS. Recurrent visual field defect and ischemic optic neuropathy associated with tadalafil rechallenge. Legal Disclaimer: All information presented in this website is intended for informational purposes only and not for the purpose of rendering medical advice.

Patient resources

Volume VII, Number 2 March/April 2004 Christina Collins, Pharm.D. Erectile dysfunction (ED) is a common disorder that affects up to 30 million men in the United States alone.1,2 ED is defined as the inability to achieve or maintain a penile erection sufficient for sexual function.3 The prevalence of this disorder increases with age and predominantly affects men over the age of 40.4,5 In addition to age, there are some disease states that predispose men to develop ED, including hypertension, diabetes mellitus, and atherosclerosis. Smoking, excessive alcohol intake, and some medications (e.g., thiazide diuretics, calcium channel blockers, beta-blockers, digoxin, selective serotonin reuptake inhibitors, and tricyclic antidepressants) may also contribute to the development of ED.4,6 ED may be categorized into three types based on the causative factors: organic, psychogenic, and multifactorial.4,6 Organic causes include diabetes, hypertension, spinal cord injuries, and some medications. Depression, psychological stress, relationship problems, and performance anxiety are all of psychogenic origin.5 Multifactorial causes are any combination of the above. With greater public awareness and discussion of ED, the demand for new and improved treatments has increased tremendously.

Consent for Publication

The phosphodiesterase type 5 (PDE-5) inhibitor sildenafil (Viagra®) has become the drug of choice for treatment of ED since it reached the market in March of 1998. This is due to sildenafil's convenience and tolerability compared to previous therapies.5 It has been shown to be beneficial in the treatment of organic and psychogenic ED.5,6 Sildenafil does have some disadvantages such as side effects and a relatively short duration of action; consequently, the search for the ideal drug to treat ED has continued. This sustained pursuit has led to the development of two new PDE-5 inhibitors: vardenafil (Levitra®; Bayer Pharmaceuticals Corporation in cooperation with GlaxoSmithKline) was approved by the Food and Drug Administration (FDA) on August 19, 2003, and tadalafil (Cialis; Eli Lilly Corporation) was FDA-approved in November 2003.2 These new agents possess distinguishing characteristics that differentiate themselves from each other and sildenafil. Sildenafil, vardenafil, and tadalafil are all PDE-5 inhibitors indicated for the treatment of ED. They do not directly cause penile erections, however, they affect the response to sexual stimulation. This allows the induction of an erection during sexual stimulation.7 Sildenafil, vardenafil, and tadalafil all affect ED through the same basic mechanism of inhibiting PDE-5 but have differing potencies and affinities for each of the 11 PDE isoenzymes. Vardenafil is the most potent PDE-5 inhibitor, followed by sildenafil and tadalafil.7 However, there is no current evidence that greater drug potency has produced improved clinical efficacy. The affinities vary for the other PDE isoenzymes, and thus may explain the potential differences in their side effect profiles.

• Tadalafil's impact on female libido is still being explored in research.
• It may help in cases where sexual dysfunction has vascular causes.
• Potential risks include hypotension and priapism, also relevant for women.
• Women with certain health conditions should avoid tadalafil.
• The drug's interaction with other medications warrants caution.
• Women in clinical trials report varied responses.
• Tadalafil might improve erectile tissue engorgement in women.
• It is sometimes used as part of comprehensive sexual therapy.
• Certified healthcare providers should guide its use.

While sildenafil, vardenafil, and tadalafil are all hepatically metabolized, there are variances in their pharmacokinetic profiles.

Sildenafil is approximately 75% metabolized, predominantly by cytochrome P450 (CYP) 3A4 with contribution from CYP 2C9.7,8 Vardenafil is primarily metabolized by CYP 3A4 and secondarily by CYP 3A5 and 2C isoforms.7,9 Tadalafil is also metabolized by CYP 3A4.2,10 With CYP 3A4 being the major enzyme responsible for the metabolism of all three agents, they will potentially have many of the same drug interactions with some possible contributions from the minor enzymatic pathways.

Other pharmacokinetic differences include time to maximum concentration and half-life. The slightly faster time to maximum concentration of vardenafil (0.7 hours) compared to sildenafil (0.8 hours) is likely clinically irrelevant, while tadalafil has the slowest onset and may require 2 hours to reach maximum concentration. Tadalafil, however, has the longest half-life (17.5 hours), followed by tadalafil 60mg uk vardenafil (4 hours) and sildenafil (3.7 hours).7-10 These differences will account for variation in dosage timing and duration of effect. The considerably longer duration of effect for tadalafil will likely allow less frequent dosing and greater impulsiveness between partners, but also could potentially prolong adverse effects. There are no comparative trials evaluating sildenafil, vardenafil, and tadalafil; therefore, it is difficult to compare the individual trials available due to differences in study design and methodology. However, all three agents have been proven effective in treating ED in clinical trials based on the Erectile Function domain score of the International Index of Erectile Function, a sexual function questionnaire commonly used throughout the studies. Efficacy rates for the PDE-5 inhibitors vary widely throughout the literature with a range of 57% to 83%.5,11-13 Additionally, they have all shown efficacy in the treatment of ED in men with diabetes mellitus; however, no particular agent has yet to be recommended for patients with cardiovascular disease.2,8,10,12,14,15 Comparative trials are required to determine if a specific agent possesses better efficacy. There are drug-drug interactions with each of these medications, many of which involve the same drugs due to CYP 3A4 being the major enzymatic pathway for all of these agents. Due to the potential for severe hypotension, sildenafil and organic nitrates (e.g., nitroglycerin, isosorbide dinitrate [Isordil®, Sorbitrate®], and isosorbide mononitrate [Imdur, ISMO®, Monoket®]) are contraindicated (i.e., should not be taken together), and sildenafil doses > 25 mg should not be used within 4 hours of taking an alpha-blocker (e.g., prazosin [Minipress®], terazosin [Hytrin®], and doxazosin [Cardura®]). Sildenafil is a substrate of CYP 3A4 and 2C8/9 as well as an inhibitor of CYP 1A2, 2C8/9, 2C19, 2D6, 2E1, and 3A4; therefore, increased effects and possible toxicity of sildenafil occur when used concomitantly with drugs that inhibit these enzymes (e.g., cimetidine [Tagamet®], erythromycin, ketoconazole [Nizoral®], itraconazole [Sporanox®], amprenavir [Agenerase®], indinavir [Crixivan®], saquinavir [Fortovase®], and ritonavir [Norvir®]). Enzyme-inducing agents, such as St. John's wort and rifampin, may have the opposite effect and cause decreased sildenafil levels. Drug-food interactions with sildenafil can also occur. The rate and extent of absorption of sildenafil is reduced when taken with a high-fat meal and grapefruit juice may cause increased serum concentrations of sildenafil, consequently, concurrent use should be avoided.8-10,16-18 Concomitant use of vardenafil is also contraindicated with alpha-blockers and organic nitrates due to the potential for severe hypotension. Vardenafil is a substrate of CYP 3A4, and to a minor extent the 2C isoforms, leading to interactions with drugs that induce or inhibit these enzymes. Other enzyme inhibitors that may increase vardenafil levels are amiodarone (Cordarone®), cimetidine (Tagamet®), clarithromycin (Biaxin®), delavirdine (Rescriptor®), diltiazem (e.g., Cardizem®, Cardizem® SR, Cardizem® CD, Cardizem® LA, Cartia XT, Dilacor® XR, Diltia XT, Taztia XT, and Tiazac®), fluoxetine (Prozac®), fluvoxamine (Luvox®), nefazodone (Serzone®), nevirapine (Viramune®), saquinavir (Fortovase®), verapamil (Calan®, Covera-HS, Isoptin®SR, Verelan®), and grapefruit juice, but there are no current recommendations for dosage adjustments with these agents.8-10,16-18 Tadalafil is also metabolized by CYP 3A4, resulting in the potential for an interaction with any drug that induces or inhibits this isoenzyme.

• Tadalafil is a phosphodiesterase type 5 inhibitor, acting on blood vessels.
• Its potential benefits for women focus on increased genital blood flow.
• Tadalafil is not approved by FDA for female sexual disorders.
• Some clinical trials report moderate improvements in women.
• It is sometimes combined with hormonal treatments.
• Psychological factors also influence female sexual satisfaction.
• Tadalafil’s effects on orgasm intensity are under research.
• Women with pre-existing health conditions should exercise caution.
• Dose adjustments may be necessary based on individual response.

Ketoconazole (Nizoral®) and ritonavir (Norvir®) have both been shown to increase tadalafil levels; other CYP 450 inhibitors (e.g., erythromycin, itraconazole [Sporanox®], and grapefruit juice), however, have yet to be evaluated, but it is likely that they will also increase tadalafil levels. Patients taking potent inhibitors of CYP 3A4 (e.g., ketoconazole [Nizoral®] or ritonavir [Norvir®]) will require a dose adjustment of tadalafil. The dose should not exceed 10 mg and should not be administered more frequently than every 72 hours. Additionally, tadalafil is thought to increase the hypotensive effect of antihypertensive agents (e.g., calcium channel blockers, diuretics, angiotensin-receptor blockers, ACE-inhibitors, or adrenergic receptor-blocking agents) and therefore should be used with caution.

What is tadalafil and how does it work?

Efficacy rates for the PDE-5 inhibitors vary widely throughout the literature with a range of 57% to 83%.5,11-13 Additionally, they have all shown efficacy in the treatment of ED in men with diabetes mellitus; however, no particular agent has yet to be recommended for patients with cardiovascular disease.2,8,10,12,14,15 Comparative trials are required to determine if a specific agent possesses better efficacy. There are drug-drug interactions with each of these medications, many of which involve the same drugs due to CYP 3A4 being the major enzymatic pathway for all of these agents. Due to the potential for severe hypotension, sildenafil and organic nitrates (e.g., nitroglycerin, isosorbide dinitrate [Isordil®, Sorbitrate®], and isosorbide mononitrate [Imdur, ISMO®, Monoket®]) are contraindicated (i.e., should not be taken together), and sildenafil doses > 25 mg should not be used within 4 hours of taking an alpha-blocker (e.g., prazosin [Minipress®], terazosin [Hytrin®], and doxazosin [Cardura®]). Sildenafil is a substrate of CYP 3A4 and 2C8/9 as well as an inhibitor of CYP 1A2, 2C8/9, 2C19, 2D6, 2E1, and 3A4; therefore, increased effects and possible toxicity of sildenafil occur when used concomitantly with drugs that inhibit these enzymes (e.g., cimetidine [Tagamet®], erythromycin, ketoconazole [Nizoral®], itraconazole [Sporanox®], amprenavir [Agenerase®], indinavir [Crixivan®], saquinavir [Fortovase®], and ritonavir [Norvir®]). Enzyme-inducing agents, such as St.

General Information

John's wort and rifampin, may have the opposite effect and cause decreased sildenafil levels. Drug-food interactions with sildenafil can also occur. The rate and extent of absorption of sildenafil is reduced when taken with a high-fat meal and grapefruit juice may cause increased serum concentrations of sildenafil, consequently, concurrent use should be avoided.8-10,16-18 Concomitant use of vardenafil is also contraindicated with alpha-blockers and organic nitrates due to the potential for severe hypotension. Vardenafil is a substrate of CYP 3A4, and to a minor extent the 2C isoforms, leading to interactions with drugs that induce or inhibit these enzymes. Other enzyme inhibitors that may increase vardenafil levels are amiodarone (Cordarone®), cimetidine (Tagamet®), clarithromycin (Biaxin®), delavirdine (Rescriptor®), diltiazem (e.g., Cardizem®, Cardizem® SR, Cardizem® CD, Cardizem® LA, Cartia XT, Dilacor® XR, Diltia XT, Taztia XT, and Tiazac®), fluoxetine (Prozac®), fluvoxamine (Luvox®), nefazodone (Serzone®), nevirapine (Viramune®), saquinavir (Fortovase®), verapamil (Calan®, Covera-HS, Isoptin®SR, Verelan®), and grapefruit juice, but there are no current recommendations for dosage adjustments with these agents.8-10,16-18 Tadalafil is also metabolized by CYP 3A4, resulting in the potential for an interaction with any drug that induces or inhibits this isoenzyme.

Centro de Pesquisa Clínica Multiusuário (CePeM)

Ketoconazole (Nizoral®) and ritonavir (Norvir®) have both been shown to increase tadalafil levels; other CYP 450 inhibitors (e.g., erythromycin, itraconazole [Sporanox®], and grapefruit juice), however, have yet to be evaluated, but it is likely that they will also increase tadalafil levels. Patients taking potent inhibitors of CYP 3A4 (e.g., ketoconazole [Nizoral®] or ritonavir [Norvir®]) will require a dose adjustment of tadalafil. The dose should not exceed 10 mg and should not be administered more frequently than every 72 hours. Additionally, tadalafil is thought to increase the hypotensive effect of antihypertensive agents (e.g., calcium channel blockers, diuretics, angiotensin-receptor blockers, ACE-inhibitors, or adrenergic receptor-blocking agents) and therefore should be used with caution. Concomitant administration of tadalafil with the alpha-blockers, except tamsulosin (Flomax®) is contraindicated. Concomitant administration of tadalafil with the alpha-blockers, except tamsulosin (Flomax®) is contraindicated. Tadalafail was evaluated in combination with doxazosin (Cardura®) and resulted in a significant increase in the blood pressure-lowering effect of doxazosin. Similarly to the other agents, tadalafil is also contraindicated with the use of organic nitrates.