Could cannabis become a therapeutic option for the eye?
In about 20 to 30 percent of patients with dry eyes, the pain does not decrease to a tolerable level despite tear substitutes and anti-inflammatory ophthalmic drugs, such as Ciclosporin A. The pain is caused by the use of a combination of the two drugs. Here, newly developed cannabis-containing eye drops could become a therapeutic option.
This was announced by Professor Dr. Philipp Steven of the University Hospital Cologne at a press conference of the German Ophthalmological Society in Berlin. The use of the ingredient tetrahydrocannabinol (THC) in the eye is plausible because it not only has an analgesic effect but also has an anti-inflammatory and wound healing promoting effect. The cornea as well as the conjunctiva of the eye have many endocannabinoid receptors.
Adding cannabinoids in eyedrops
Like other cannabinoids, THC is only poorly soluble in water, which was previously an obstacle to its use on the eye. Steven’s research group and a pharmaceutical company from Heidelberg have investigated the galenic problem and developed THC-containing eye drops based on anhydrous semifluorinated alkanes (SFA). These are linear molecules with a perfluorocarbon and a hydrogen carbon content.
Steven explained that the THC-SFA eye drops, for which a patent application had been filed, could be used to apply large amounts of the active ingredient to the eye surface. In experiments with mice, the use of eye drops has led to a significant improvement in dry eyes and the function of the nerve endings.