Phosphodiesterase Inhibitors in Glaucoma Study (PhiGS)

• Status: Suspended
• Trial end date: 2022-10-30
• Target enrollment: 0
• Participant gender: Male

Summary

It is commonly known that high eye pressure is associated with glaucoma. However, there is also a theory that poor circulation to the eye is a contributing factor. Therefore, if we can increase the flow of blood to the eye, we may be able to stop people losing vision from this disease.

Phosphodiesterase inhibitors (for example sildenafil, tadalafil, Viagra®, Cialis®) are drugs used to improve blood flow to certain parts of the body. They are commonly used on an ad-hoc basis to treat erectile dysfunction, in addition to problems with blood circulation to the lungs, fingers and toes.

The majority of previous work in this field has been completed using insensitive, poorly reproducible techniques such as colour doppler ultrasound. Since then, a new imaging modality able to image blood flow in blood vessels without the need for the injection of contrast has entered clinical use.

This initial pilot study is designed as a proof-of-concept study to investigate whether we can measure detectable changes in the blood flow to the retina and choroid at the back of the eye following ingestion of a phosphodiesterase inhibitor medication by healthy and glaucomatous volunteers already taking this medication for erectile dysfunction.

• Phase: Phase 3
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Imperial College London
• Treatments: Phosphodiesterase Inhibitors; Sildenafil Citrate; Tadalafil

Criteria

Inclusion Criteria:

• Able to give informed consent to participate in the study

• Aged between 40 and 80 years of age

• Clear optical media

• Spherical equivalent +-10D

• IOP 21mmHg

Exclusion Criteria:

• have used sildenafil for 48 hours (4 hour half-life) and tadalafil for 5 days (48 hour half-life).

• have a known adverse reaction to any phosphodiesterase inhibitors

• have an inherited photoreceptor disease (manufacturer contra-indication)

• have any other known ocular disease (except glaucoma in this cohort)

• have had non-arteritic anterior ischaemic optic neuropathy (manufacturer precaution due to lack of long term visualfield studies)

• are on current ritonavir, erythromycin, cimetidine treatment (Manufacturer advises if concurrent use of ritonavir is unavoidable, the max. dose should not exceed 25 mg within 48 hours)

• have serious cardiac or liver disease (manufacturer contra-indication)

• have had a stroke or myocardial infarction (manufacturer contra-indication) within 6 months

• have anatomical deformation of the penis or conditions predisposing to priapism (sickle cell anaemia, leukaemia, multiple myeloma)

• have hypotension (manufacturer contra-indication) BP<100/60

• have secondary or narrow/closed angle glaucoma