SAR407899 is a potent, ATP-competitive Rho kinase inhibitor. It antihypertensive action in animals. Sanofi is developing SAR 407899 for the treatment of microvascular angina (Syndrome X). It was previously being developed in clinical trials for the treatment of diabetic neuropathies, diabetic nephropathies, erectile dysfunction, pulmonary hypertension, hypertension and kidney disorders, but development was discontinued for those indications.

Gisadenafil is a phosphodiesterase V inhibitor in clinical development at Pfizer. It had been in phase II clinical trials for the treatment of Benign prostatic hyperplasia; Chronic obstructive pulmonary disease; Erectile dysfunction; Overactive bladder. Treatment-emergent adverse events were: headache, myalgia, dyspepsia, back pain.

Yohimbine is a plant alkaloid with alpha-2-adrenergic blocking activity. Yohimbine has been used as a mydriatic and in the treatment of impotence. The exact mechanism for its use in impotence has not been fully elucidated. Yohimbine exerts antagonist actions at halpha(2A)-AR, h5-HT(1B), h5-HT(1D), and hD(2) sites, partial agonist actions at h5-HT(1A) sites. Yohimbine-mediated norepinephrine release at the level of the corporeal tissues may also be involved. In addition, beneficial effects may involve other neurotransmitters such as dopamine and serotonin and cholinergic receptors. Yohimbine has a mild anti-diuretic action, probably via stimulation of hypothalmic center and release of posterior pituitary hormone. Reportedly yohimbine exerts no significant influence on cardiac stimulation and other effects mediated by (beta)-adrenergic receptors. Its effect on blood pressure, if any, would be to lower it; however, no adequate studies are at hand to quantitate this effect in terms of Yohimbine dosage. Side effect of Yohimbine include anxiety, tremor, palpitations, diarrhea, and supine hypertension.

The inhibition of cyclic nucleotide Phosphodiesterase type 5 (PDE5) has been clinically validated as an effective treatment for erectile dysfunction. One of them is mirodenafil (formerly known as SK-3530) approved only in Korea. This drug was developed by SK Chemicals and marketed under the trade name Mvix.

Moxisylyte, also known as thymoxamine, is a drug used in urology for the treatment of erectile dysfunction, also was studied, that this drug may be useful to treat ocular disorders such as diabetic retinopathy. It is an alpha1-adrenergic antagonist. Was developed for self-injection therapy in France and marketed in several European countries as Icavex. In the spring 2005 the manufacturer of Icavex decided to withdraw this drug from Europe market, presumable due to its low market shares.