Selectivity of avanafil, a PDE5 inhibitor for the treatment of erectile dysfunction: implications for clinical safety and improved tolerability.

INTRODUCTION: Phosphodiesterase type 5 (PDE5) inhibitors are indicated for the treatment of erectile dysfunction (ED); however, they can also inhibit other PDE isozymes, affecting their target tissues (e.g., PDE1: heart; PDE6: retina; and PDE11: skeletal muscle), which in some cases can cause unwanted side effects and therapy discontinuation. Data from in vitro studies showed that avanafil, a PDE5 inhibitor for the treatment of ED, exhibited strong selectivity toward PDE5 and against all other PDE isozymes. AIM: To review the inhibitory effects of avanafil for PDE isozymes compared with those of sildenafil, tadalafil, and vardenafil and to discuss these results within the context of clinical trial safety observations. METHODS: Review of in vitro selectivity data for avanafil (published primary data from a peer-reviewed journal and scientific congress abstracts); PubMed search for pertinent publications on PDE5 inhibitor safety data; and review of published articles and abstracts from avanafil phase 1, 2, and 3 clinical trials. MAIN OUTCOME MEASURES: A low incidence of some PDE-related adverse events may be reflected by the high selectivity of avanafil against non-PDE5 isozymes. RESULTS: Avanafil is highly selective toward PDE5 and against all other PDE isozymes tested. Lower selectivity against PDE1, PDE6, and PDE11 is consistent with results from randomized, placebo-controlled, phase 3 trials in which musculoskeletal and hemodynamic adverse events were reported in <2% of patients and no color vision-related abnormalities were reported with avanafil doses up to 200 mg once daily. CONCLUSIONS: Data suggest that avanafil may confer a safety benefit, in terms of a lower incidence of specific adverse events, by virtue of its high specificity to PDE5 and its overall selectivity against other PDE isozymes.

Clinical cure of bacterial conjunctivitis with azithromycin 1%: vehicle-controlled, double-masked clinical trial.

PURPOSE: To analyze the effect of azithromycin 1% ophthalmic solution in DuraSite (InSite Vision, Inc, Alameda, California, USA) on bacterial conjunctivitis. DESIGN: Prospective, randomized, vehicle-controlled, parallel-group, double-masked multicenter clinical study. METHODS: Eligible male or female participants with a clinical diagnosis of acute bacterial conjunctivitis were randomized to either 1% azithromycin in DuraSite or vehicle for five days. Infected eyes were dosed twice daily on days 1 and 2 and once daily on days 3 through 5. Conjunctival cultures were obtained at baseline, visit 2 (day 3 or 4), and visit 3 (day 6 or 7). The primary end point was clinical resolution of signs and symptoms (rating of zero on ocular discharge, bulbar and palpebral injection) at visit 3. Efficacy measures were clinical resolution and bacterial eradication as evaluated in the per-protocol population. Safety was assessed by adverse events, slit-lamp findings, and ophthalmoscopy. RESULTS: Two hundred and seventy-nine participants (n = 130, 1% azithromycin in DuraSite; n = 149, vehicle), age one to 96 years, were evaluated for efficacy. Clinical resolution with azithromycin ophthalmic solution was statistically significant compared with that of vehicle (P = .030) at visit 3. Bacterial eradication rates with azithromycin ophthalmic solution reached 88.5% at visit 3 (P < .001) and included some pathogens resistant to azithromycin in vitro. Overall, adverse event rates were similar in both treatment groups. CONCLUSIONS: Azithromycin 1% ophthalmic solution in DuraSite showed statistically significant differences in clinical resolution and bacterial eradication rates when compared with vehicle. Because it was well tolerated in this population, it may be a viable treatment option for children and adults with bacterial conjunctivitis.

Gatifloxacin 0.5% administered twice daily for the treatment of acute bacterial conjunctivitis in patients one year of age or older.

PURPOSE: To evaluate the efficacy and safety of gatifloxacin 0.5% ophthalmic solution administered twice daily for treatment of acute bacterial conjunctivitis. METHODS: Two identically designed, double-masked, multicenter studies in the United States and India enrolled patients 1 year or older with acute bacterial conjunctivitis. Patients were randomized to gatifloxacin 0.5% or vehicle treatment for 5 days. Clinical success in clearing conjunctival hyperemia and discharge at day 6 (primary endpoint) and day 4 and microbiological cure were determined. Isolates from positive conjunctival samples were tested for sensitivity and susceptibility. Safety measures included adverse events (AEs). Data from these 2 studies were pooled for these analyses. RESULTS: Of the 1437 randomized patients, 658 constituted the modified intent-to-treat population. Patient characteristics were similar between the pooled treatment groups. Clinical success occurred for 58.0% of gatifloxacin 0.5%-treated versus 45.5% vehicle-treated patients at day 6 (P=0.001) and for 23.7% versus 15.4% in the respective groups at day 4 (P=0.007). Microbiological cure was higher with gatifloxacin 0.5% than vehicle at days 4 and 6 (P<0.001 for both time points). The combined minimum inhibitory concentration required to inhibit 90% of isolates for gatifloxacin 0.5% was 2.0 µg/mL for gram-positive and gram-negative organisms. AEs were reported by 11.6% and 13.3% of patients in the gatifloxacin 0.5% and vehicle safety populations, respectively. One patient in each treatment group experienced a serious AE; neither was treatment related. CONCLUSIONS: The 0.5% concentration of gatifloxacin ophthalmic solution was safe and effective for treatment of acute bacterial conjunctivitis with twice-daily administration for 5 days.

Topical ophthalmic moxifloxacin elicits minimal or no selection of fluoroquinolone resistance among bacteria isolated from the skin, nose, and throat.

PURPOSE: To investigate whether moxifloxacin therapy of bacterial conjunctivitis in children changes the moxifloxacin susceptibility of bacterial isolates in eyes, cheeks below eyes, nares, and throat. METHODS: Patients (age: 1 to 12 years, n = 105) with bacterial conjunctivitis were treated topically with moxifloxacin three times a day for 7 days. Gender- and age-matched subjects with normal eyes (age: 1 to 12 years, n = 57) served as the control group. Microbiological specimens were collected on days 1 (prior to therapy), 8 (1 day after end of therapy), and 42 (follow-up). Specimens were processed to recover total bacteria and bacteria that grew on fluoroquinolone-selective media. Bacteria were identified to the species level and susceptibility to moxifloxacin and selected other antibiotics determined. RESULTS: The primary pathogens recovered from the infected eyes on day 1 before therapy were Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus. None of the pre-therapy isolates of H. influenzae and S. pneumoniae were resistant to moxifloxacin. Isolates of these two pathogenic species were also recovered primarily from the nose and eyes. Moxifloxacin-resistant S. aureus isolates (minimum inhibitory concentration 1.0 µg/mL or greater) were recovered from the nose and throat prior to topical dosing on day 1. However, there was no change in the frequency of moxifloxacin-resistant isolates of S. aureus following treatment with moxifloxacin. CONCLUSION: Treatment of conjunctivitis with topical ophthalmic moxifloxacin did not select for moxifloxacin resistance in H. influenzae, S. pneumoniae, or S. aureus in the eye or distal body sites.

Phase III efficacy and safety study of besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial conjunctivitis.

OBJECTIVE: To compare the clinical and antimicrobial efficacy of besifloxacin ophthalmic suspension 0.6% with that of vehicle in the treatment of bacterial conjunctivitis. RESEARCH DESIGN AND METHODS: This was a randomized, multicenter, double-masked, vehicle-controlled study. A total of 957 patients aged 1 year and older with bacterial conjunctivitis were randomized to treatment with besifloxacin ophthalmic suspension 0.6% or vehicle applied topically three times daily for 5 days. MAIN OUTCOME MEASURES: Primary endpoints were clinical resolution and microbial eradication of baseline bacterial infection at Visit 2 (Day 5 +/- 1). Secondary endpoints included clinical resolution and microbial eradication at Visit 3 (Day 8 or 9), individual clinical outcomes at follow-up visits, and safety. CLINICAL TRIAL REGISTRATION: NCT number, NCT00347932. RESULTS: Three hundred and ninety patients had culture-confirmed bacterial conjunctivitis. Clinical resolution and microbial eradication were significantly greater with besifloxacin ophthalmic suspension than with vehicle at Visit 2 (45.2% vs. 33.0%, p = 0.0084; and 91.5% vs. 59.7%, p < 0.0001, respectively) and Visit 3 (84.4% vs. 69.1%, p = 0.0011; and 88.4% vs. 71.7%, p < 0.0001, respectively). Results for secondary endpoints of individual clinical outcomes were consistent with primary endpoints. Fewer eyes receiving besifloxacin ophthalmic suspension experienced adverse events than those receiving vehicle (9.2% vs. 13.9%; p = 0.0047). CONCLUSIONS: Besifloxacin ophthalmic suspension produces clinical resolution and microbial eradication rates significantly better than vehicle and is safe for the treatment of bacterial conjunctivitis. LIMITATIONS: A limitation of this study is the lack of a non-treatment control group.