Eye Diseases: Visual sense Eye Diseases Visual sense
Conditions
Interventions
Sildenafil (Viagra) and similar drugs eg tadalafil are phosphodiesterase type 5 inhibitor drugs that have been widely used in the treatment of erectile dysfunction in humans. One of the possible side
Sponsors
Record Provided by the NHSTCT Register - 2007 Update - Department of Health
Eligibility
Sex/Gender
Male
Inclusion criteria
Inclusion criteria: Healthy male subjects aged 18-55 years. We have decided to only recruit male volunteers because phosphodiesterase inhibitors such as sildenafil and tadalafil are almost exclusively used in male patients.
Exclusion criteria
Exclusion criteria: 1. Volunteers suffering from any significant medical or psychiatric illness. Subjects may be enrolled at the discretion of the principal investigator or his designated deputy if the illness would not affect the validity of the study or pose an added risk to the subject (e.g. mild asthma, hay fever). Specific conditions that will exclude volunteers from taking part are as follows: 1.1 Cardiac disease 1.2 Blood pressure 160/100mmHg on screening visit 1.3 Renal disease 1.4 Liver disease 1.5 Stroke 1.6 Sickle cell anaemia 1.7 Multiple myeloma 1.8 Leukaemia 1.9 Bleeding disorders 1.10 Peyronie's disease 1.11 Priapism 2. Subjects receiving prescribed medications. Subjects may be included if the medication prescribed would not be considered to affect the validity of the study or pose an added risk to the study subject (e.g. inhaled asthma therapy). Specific exclusions include the following (due to interaction with the study drugs): nitrates, nicorandil, alpha blockers, erythromycin, cimetidine, rifampicin, phenytoin, carbamazepine, Phenobarbital, ritonavir, saquinavir, ketoconazole, itraconazole. 3. Female subjects 4. Subjects with known visual abnormalities other than refractive errors, including specifically: retinitis pigmentosa, optic neuropathy
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Effects of the drugs on retinal time constants (visual persistence and reaction times) | — |
Secondary
| Measure | Time frame |
|---|---|
| 1. Effects of drugs on retinal time constants in different types of photoreceptors 2. Effect of PDE6 genotype on drug effects on retinal time constants | — |
Countries
United Kingdom
Outcome results
None listed