The randomization assigned 49 patients to receive active sildenafil and 49 to receive identical placebo.
| Drug Name | Mechanism | Approval Status | Cost per Dose | Common Side Effects |
|---|---|---|---|---|
| Sildenafil | PDE5 inhibitor | Not officially approved | $10-$20 | Headache, flushing |
| Tadalafil | Longer duration, PDE5 inhibitor | Limited use | $15-$30 | Muscle pain, headache |
| Vardenafil | Similar to sildenafil | Experimental | $12-$25 | Vision changes |
The only restriction to this randomization was that the groups be of equal size. The largest difference in numbers assigned to the 2 groups at any point in the trial was 4 (excludes completions).
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At baseline, patients were allocated to the next available number that randomly assigned them to receive sildenafil or matching placebo (50-mg starting dose). Medications were sealed in sequentially numbered identical containers according to allocation sequence, and all study personnel and participants were blinded to treatment assignment for the duration of the study. Patients were instructed to take 1 tablet of trial medication approximately 1 to 2 hours before anticipated sexual activity, not more than once daily over the 8-week trial period and were required to make at least 1 attempt but were asked to try to make at least 2 attempts at sexual activity per week.
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The dose of study drug could be adjusted from 1 (50 mg) to 2 (100 mg) tablets based on investigator judgment of efficacy and tolerability, including the recording of the findings that resulted in any study drug dosage change and adverse events. Patients were given diaries with instructions for recording trial medication use and sexual activity. Sildenafil and placebo were provided by Pfizer Inc, New York, New York. Drug accountability, concomitant antidepressant treatment, vital signs, and self-rated and physician-rated symptom reports were assessed at each visit (weeks 2, 4, and 8), which included diary review and return of unused medication.
Does Viagra help women?
A urine pregnancy test was administered to all women of childbearing potential at each visit. Investigators monitored, collected, and followed up on any spontaneous reports of adverse events, and they assessed and categorized the severity of the events and their relationship to the study drug throughout the trial. Efficacy was assessed using 4 validated measurements. The primary efficacy outcome measure was the difference between the 2 treatment groups in end point mean improvement scores (ie, lower ordinal score) on the Clinical Global Impression Scale adapted for sexual function.26 Secondary outcome measures were baseline to end point mean scores on the Sexual Function Questionnaire,27 the Arizona Sexual Experience scale–female version,28 and the University of New Mexico Sexual Function Inventory–female version.29 Patient-recorded event logs were reviewed for the frequency and percentage of successful intercourse attempts, the number of satisfactory attempts at orgasm or climax, and used to corroborate ratings. Participants were seen at baseline and at weeks 2, 4, and 8 (or last visit) for assessments that included measures of change from baseline to weeks 2, 4, and 8 (or last visit).
Mohamed Alhefnawy1*, Abdulla Esawy2, Mohamed Abdelazeem1, Mohamed Elnamoury3, Ahmed Eissa4, Ahmed Zoair4, Ahmed Ghaith4, Ayman Hagras4 and Khaled Almekaty4
The Clinical Global Impression scale is a clinician-rated severity improvement scale derived from a review of the diary and discussion with the patient for measuring sexual function with changes measured from baseline to weeks 2, 4, and 8 (final or last visit) with anchored scores from 1 (normal) to 7 (most extreme sexual dysfunction).26 The sexual function questionnaire is a 34-item, multidimensional, patient-rated, self-report, outcome measure of female sexual function developed and validated in English and several other languages.27 It quantifies sexual function in 7 functional domains (desire, arousal-sensation, arousal-lubrication, orgasm, enjoyment, pain, partner) of the female sexual response cycle to detect change in and distinguish between the presence and absence of female sexual dysfunction consistent with the DSM-IV diagnostic criteria. Anchored 5- or 7-point individual item response scales are scored, ascending or descending, from 0 or higher to 6 or lower (most are 1 to 5) with the higher scores indicating better sexual function. The 7 domain composite–section scores add to a total score range of 30 to 167: sexual desire (range, 5-31), arousal-sensation (range, 4-20), arousal-lubrication (range, 2-10), orgasm (range, 3-15), pain (range, 2-15), partner (range, 2-10), and enjoyment (range, 6-30). Responses of not applicable were entered as missing. To provide concurrent validity, we used the Arizona Sexual Experience and the University of New Mexico Sexual Function Inventory scales. A urine pregnancy test was administered to all women of childbearing potential at each visit. Investigators monitored, collected, and followed up on any spontaneous reports of adverse events, and they assessed and categorized the severity of the events and their relationship to the study drug throughout the trial.
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Among the most frequent causes for exclusion were ineligible protocol criteria (ie, lack of acceptable and verifiable form of contraception, perimenopausal with irregular cycles or amenorrhea, non-SRI sexual dysfunction augmentation, switching antidepressant agent, other treatments for sexual dysfunction), and other miscellaneous reasons (partner issues, abnormal Papanicolaou test results, medical comorbidity, excessive alcohol use, or relationship or partner problems).
Female neurogenic sexual dysfunction secondary to clitoral neuropathy
Efficacy was assessed using 4 validated measurements. The primary efficacy outcome measure was the difference between the 2 treatment groups in end point mean improvement scores (ie, lower ordinal score) on the Clinical Global Impression Scale adapted for sexual function.26 Secondary outcome measures were baseline to end point mean scores on the Sexual Function Questionnaire,27 the Arizona Sexual Experience scale–female version,28 and the University of New Mexico Sexual Function Inventory–female version.29 Patient-recorded event logs were reviewed for the frequency and percentage of successful intercourse attempts, the number of satisfactory attempts at orgasm or climax, and used to corroborate ratings. Participants were seen at baseline and at weeks 2, 4, and 8 (or last visit) for assessments that included measures of change from baseline to weeks 2, 4, and 8 (or last visit). The Clinical Global Impression scale is a clinician-rated severity improvement scale derived from a review of the diary and discussion with the patient for measuring sexual function with changes measured from baseline to weeks 2, 4, and 8 (final or last visit) with anchored scores from 1 (normal) to 7 (most extreme sexual dysfunction).26 The sexual function questionnaire is a 34-item, multidimensional, patient-rated, self-report, outcome measure of female sexual function developed and validated in English and several other languages.27 It quantifies sexual function in 7 functional domains (desire, arousal-sensation, arousal-lubrication, orgasm, enjoyment, pain, partner) of the female sexual response cycle to detect change in and distinguish between the presence and absence of female sexual dysfunction consistent with the DSM-IV diagnostic criteria.
- Sildenafil can enhance arousal in women with sexual issues.
- It works by relaxing blood vessels, increasing genital blood flow.
- Dosage for women is not well established; consult a doctor.
- Its effectiveness varies among women with sexual dysfunction.
Anchored 5- or 7-point individual item response scales are scored, ascending or descending, from 0 or higher to 6 or lower (most are 1 to 5) with the higher scores indicating better sexual function. The 7 domain composite–section scores add to a total score range of 30 to 167: sexual desire (range, 5-31), arousal-sensation (range, 4-20), arousal-lubrication (range, 2-10), orgasm (range, 3-15), pain (range, 2-15), partner (range, 2-10), and enjoyment (range, 6-30). Responses of not applicable were entered as missing. To provide concurrent validity, we used the Arizona Sexual Experience and the University of New Mexico Sexual Function Inventory scales. Both are shorter and well-established instruments that have been validated in patients with psychiatric disorders. They weight sexual function domains equally with different wording and anchors at administration.
| Parameter | Typical Value | Notes |
|---|---|---|
| Absorption | Rapid, peaks in 30-120 minutes | Food can delay absorption |
| Distribution | Widely distributed in tissues | Binds to plasma proteins |
| Metabolism | Liver CYP3A4 enzymes | Excreted mainly in feces |
| Half-life | 4-5 hours | Duration of action varies |
The Arizona scale is a 5-item, patient-rated questionnaire that quantifies sexual drive, arousal (subjective excitement), lubrication (physiological excitement), ability to reach orgasm, and orgasm satisfaction using anchored 6-point scales from 1 (good function) to 6 (poor function) for each item with a total score ranging from 5 to 30 (higher scores indicate greater sexual dysfunction).28 The University of New Mexico scale29 is a 5-item, clinician-rated—for this study—questionnaire derived from and similar to the Arizona28 and the Massachusetts General Hospital-Sexual Function questionnaires.30 It uses anchored 6-point scales from 1 (good function) to 6 (poor function) for each item (desire, sexual arousal, ability to achieve lubrication, ability to achieve orgasm, and overall satisfaction) to quantify presence and changes in sexual dysfunction independent of disease state or medication (lower scores indicate better or improvement in sexual function). The 17-item Hamilton depression rating23 was administered at baseline and at weeks 2, 4, and 8 (or last visit) to monitor depression severity to ensure that the severity of depression had not changed to be more than 10 (relapse of major depression excluded study continuation). A second Hamilton anxiety sildenafil 20 mg prescription rating24 occurred at week 8.
What should I do if I forget to take a dose?
The χ2 analyses were used to evaluate group differences in categorical measures. Analyses were based on intent-to-treat with the last-observation-carried-forward analyses performed on all variables and included data from all protocol-treated patients. All randomized patients received and took at least 1 dose of study trial medication, had at least 1 efficacy assessment, and were included regardless of protocol deviations or whether they completed the study. The final analysis included women who completed the trial, but for the women who did not complete the trial, their baseline value was carried forward in separate analyses. The change in sexual functioning by Clinical Global Impression sexual function score and all other questionnaires from baseline to each patient's own end point were the dependent measures of efficacy.
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A repeated measures analysis of variance was used to determine differences between placebo and sildenafil in the change from baseline to end point for the measures of efficacy and depression severity (time × group interaction). In addition, exact nonparametric methods were applied to the efficacy measures to substantiate results that rely on distributional assumptions. Findings were also confirmed with analysis of covariance and Wilcoxon rank sum tests for primary analyses. All statistical tests were 2-sided, and all hypotheses were evaluated at the 5% significance level. The F test of the overall hypothesis test was first conducted before multiple comparisons analyses. The clinical assessment of each patient and medical record was used to confirm DSM-IV–defined major depressive disorder in remission, substance-induced sexual dysfunction, and any exclusionary diagnoses. Serum blood samples drawn at baseline and at study end, before 11 AM on days 1 to 10 of the menstrual period (follicular phase), were stored at −80°C until assayed and measured following prescribed procedures (eg, chemiluminescent enzyme immunoassay, microparticle enzyme immunoassay, radioimmunoassay) at the Reproductive Endocrine Reference Laboratory at Massachusetts General Hospital, Boston. Full analysis procedures with lower limits of detection reported for assays performed at the Massachusetts General Hospital General Clinical Research Center core laboratory using commercially available kits are published by the manufacturer and available on request.
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The randomization assigned 49 patients to receive active sildenafil and 49 to receive identical placebo. The only restriction to this randomization was that the groups be of equal size. The largest difference in numbers assigned to the 2 groups at any point in the trial was 4 (excludes completions). At baseline, patients were allocated to the next available number that randomly assigned them to receive sildenafil or matching placebo (50-mg starting dose). Medications were sealed in sequentially numbered identical containers according to allocation sequence, and all study personnel and participants were blinded to treatment assignment for the duration of the study.
Cite this article
Patients were instructed to take 1 tablet of trial medication approximately 1 to 2 hours before anticipated sexual activity, not more than once daily over the 8-week trial period and were required to make at least 1 attempt but were asked to try to make at least 2 attempts at sexual activity per week. The dose of study drug could be adjusted from 1 (50 mg) to 2 (100 mg) tablets based on investigator judgment of efficacy and tolerability, including the recording of the findings that resulted in any study drug dosage change and adverse events. Patients were given diaries with instructions for recording trial medication use and sexual activity. Sildenafil and placebo were provided by Pfizer Inc, New York, New York. Drug accountability, concomitant antidepressant treatment, vital signs, and self-rated and physician-rated symptom reports were assessed at each visit (weeks 2, 4, and 8), which included diary review and return of unused medication. Baseline demographics, safety, and tolerability evaluations were compared using descriptive statistics by χ2 and Fisher exact tests (when cell sizes were <5).
Other FDA‑approved treatments for low libido in women
Both are shorter and well-established instruments that have been validated in patients with psychiatric disorders. They weight sexual function domains equally with different wording and anchors at administration. The Arizona scale is a 5-item, patient-rated questionnaire that quantifies sexual drive, arousal (subjective excitement), lubrication (physiological excitement), ability to reach orgasm, and orgasm satisfaction using anchored 6-point scales from 1 (good function) to 6 (poor function) for each item with a total score ranging from 5 to 30 (higher scores indicate greater sexual dysfunction).28 The University of New Mexico scale29 is a 5-item, clinician-rated—for this study—questionnaire derived from and similar to the Arizona28 and the Massachusetts General Hospital-Sexual Function questionnaires.30 It uses anchored 6-point scales from 1 (good function) to 6 (poor function) for each item (desire, sexual arousal, ability to achieve lubrication, ability to achieve orgasm, and overall satisfaction) to quantify presence and changes in sexual dysfunction independent of disease state or medication (lower scores indicate better or improvement in sexual function). The 17-item Hamilton depression rating23 was administered at baseline and at weeks 2, 4, and 8 (or last visit) to monitor depression severity to ensure that the severity of depression had not changed to be more than 10 (relapse of major depression excluded study continuation). A second Hamilton anxiety sildenafil 20 mg prescription rating24 occurred at week 8.
Sexual Health in the Neurogenic Patient
The clinical assessment of each patient and medical record was used to confirm DSM-IV–defined major depressive disorder in remission, substance-induced sexual dysfunction, and any exclusionary diagnoses. Serum blood samples drawn at baseline and at study end, before 11 AM on days 1 to 10 of the menstrual period (follicular phase), were stored at −80°C until assayed and measured following prescribed procedures (eg, chemiluminescent enzyme immunoassay, microparticle enzyme immunoassay, radioimmunoassay) at the Reproductive Endocrine Reference Laboratory at Massachusetts General Hospital, Boston. Full analysis procedures with lower limits of detection reported for assays performed at the Massachusetts General Hospital General Clinical Research Center core laboratory using commercially available kits are published by the manufacturer and available on request. Baseline demographics, safety, and tolerability evaluations were compared using descriptive statistics by χ2 and Fisher exact tests (when cell sizes were <5). Independent samples t tests compared baseline patient characteristics and Clinical Global Impression sexual function scores between the study groups at end point. Independent samples t tests compared baseline patient characteristics and Clinical Global Impression sexual function scores between the study groups at end point. The χ2 analyses were used to evaluate group differences in categorical measures. Analyses were based on intent-to-treat with the last-observation-carried-forward analyses performed on all variables and included data from all protocol-treated patients. All randomized patients received and took at least 1 dose of study trial medication, had at least 1 efficacy assessment, and were included regardless of protocol deviations or whether they completed the study.
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Sample-size calculations were based on detecting a difference in full response rates at 8 weeks, assuming a response rate of 70% for sildenafil and 35% for placebo. Thus, a sample size of 82 evaluable patients (41 per group) was expected to detect a significant difference with 90% power for a type I error rate of α = .05 between sildenafil and placebo (2-sided). Assuming 20% attrition, 100 patients were planned to be randomized and 98 patients were entered. The sample size determination assumed no interactions of treatment with site or antidepressant. The primary analysis was according to assignment at randomization.
Future Directions
In addition to determination of this narrow measure of efficacy based on all randomized patients and imputing the worst rank scores for early exclusions due to protocol violations before and without taking the trial drug, there was a general efficacy analysis for all protocol-treated patients and all trial completers. Adjusted means (SDs) were determined and reported. Where applicable, 95% confidence intervals (CIs) are provided. Analyses were performed with SAS version 9.1.3 (SAS Institute Inc, Cary, North Carolina). One hundred women (Figure) of the 145 screened met eligibility requirements. The final analysis included women who completed the trial, but for the women who did not complete the trial, their baseline value was carried forward in separate analyses. The change in sexual functioning by Clinical Global Impression sexual function score and all other questionnaires from baseline to each patient's own end point were the dependent measures of efficacy. A repeated measures analysis of variance was used to determine differences between placebo and sildenafil in the change from baseline to end point for the measures of efficacy and depression severity (time × group interaction). In addition, exact nonparametric methods were applied to the efficacy measures to substantiate results that rely on distributional assumptions. Findings were also confirmed with analysis of covariance and Wilcoxon rank sum tests for primary analyses. All statistical tests were 2-sided, and all hypotheses were evaluated at the 5% significance level.
- Research shows mixed results on sildenafil's benefits for women.
- It may improve sexual satisfaction in some women.
- Not recommended for women with cardiovascular conditions.
- Using sildenafil without medical advice is risky.
The F test of the overall hypothesis test was first conducted before multiple comparisons analyses. Sample-size calculations were based on detecting a difference in full response rates at 8 weeks, assuming a response rate of 70% for sildenafil and 35% for placebo.
| Area of Research | Focus | Expected Outcomes | Challenges |
|---|---|---|---|
| Larger clinical trials | Efficacy and safety validation | Better approval pathway | Funding, recruitment difficulties |
| Combination therapies | Sildenafil with hormonal or psychological treatments | Enhanced effects | Interaction management |
| Delivery methods innovations | Topical, transdermal, or implantable forms | Increased convenience | Development complexity |
| Long-term safety studies | Effects of prolonged use | Safety confirmation | Ethical and logistical hurdles |
Thus, a sample size of 82 evaluable patients (41 per group) was expected to detect a significant difference with 90% power for a type I error rate of α = .05 between sildenafil and placebo (2-sided). Assuming 20% attrition, 100 patients were planned to be randomized and 98 patients were entered. The sample size determination assumed no interactions of treatment with site or antidepressant. The primary analysis was according to assignment at randomization. In addition to determination of this narrow measure of efficacy based on all randomized patients and imputing the worst rank scores for early exclusions due to protocol violations before and without taking the trial drug, there was a general efficacy analysis for all protocol-treated patients and all trial completers. Adjusted means (SDs) were determined and reported. Where applicable, 95% confidence intervals (CIs) are provided. Analyses were performed with SAS version 9.1.3 (SAS Institute Inc, Cary, North Carolina). One hundred women (Figure) of the 145 screened met eligibility requirements. Among the most frequent causes for exclusion were ineligible protocol criteria (ie, lack of acceptable and verifiable form of contraception, perimenopausal with irregular cycles or amenorrhea, non-SRI sexual dysfunction augmentation, switching antidepressant agent, other treatments for sexual dysfunction), and other miscellaneous reasons (partner issues, abnormal Papanicolaou test results, medical comorbidity, excessive alcohol use, or relationship or partner problems).
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