Although all PDE5 inhibitors share the same mechanism of action, each agent has different pharmacokinetics and pharmacodynamics which affect how quickly it acts, how long its effects last, and its side effects. Notably, although all PDE5 inhibitors preferentially inhibit PDE5, the degree to which they also inhibit other phosphodiesterases influences their side effect profile. For example, sildenafil also inhibits PDE6 which is present in the retina of the eye; this reaction is thought to be responsible for the temporary visual changes which some patients using sildenafil experience. Similarly tadalafil also inhibits PDE11 which is present in the prostate, although no effects on fertility have been reported. Although agents more selective for PDE5 were in development, these trials have been suspended, likely due to the saturation of the market with the introduction of agents with broad cardiovascular benefits, such as SGLT2 inhibitors and endothelin receptor antagonists.