Prizidilol (also known as SKF 92657) is arylpyridazinylhydrazine derivative patented by Smith Kline and French Laboratories Ltd. as an antihypertensive agent. In clinical trials, Supine and standing blood pressure measured 24--27 h after drug intake was reduced Slight but significant decreases in heart rate were seen after moderate doses of prizidilol. A more pronounced blood pressure reduction was noticed 2--7 h after drug administration. Prizidilol was well tolerated, although dizziness and tiredness were reported by four patients and edema by two.

Prinoxodan (also known as RGW2938) is a benzodiazinone derivative patented by Rorer International (Overseas), Inc as inotropic agents, useful in treating congestive heart failure. Prinoxodan administered intravenously (i.v.) to anesthetized dogs increased contractile force while decreasing arterial pressure and total peripheral resistance (TPR) in a dose-related manner. A single oral dose of Prinoxodan administered to conscious chronically instrumented dogs produced a marked and sustained increase in contractility 15-240 min after treatment.

Premazepam is a pyrrolodiazepine derivative patented by Gruppi Lepetit S.p.A. as a muscle relaxant. Premazepam is a partial agonist of benzodiazepine receptors and was shown in 1984 to possess both anxiolytic and sedative properties in humans. Premazepam had a different EEG profile from diazepam, producing slower and less fast wave activity. In the single dose study, its effects were similar to diazepam for sedative action and most of the psychological tests, with a tendency towards greater psychomotor impairment. In the repeated dose study, however, premazepam caused less sedation and also tended to produce less psychomotor impairment.

Pipoxizine is the antihistamine agent and antiserotonin agent. It was used as antiarrhythmic and bronchodilator.

Pifenate is an analgesic agent.

Nicaraven is a hydroxyl radical scavenger with antivasospastic and neuroprotective effects. Chugai (the Japanese subsidiary of Roche) is developing nicaraven (Antevas), a water-soluble antioxidant, for the potential treatment of disorders caused by acute cerebrovascular diseases. A registration application was filed in April 1995, and in April 2002, nicaraven was still awaiting registration in Japan. By August 2002, Chugai had filed an NDA in Japan for the additional indication of subarachnoidal bleeding.