Fenobam is a selective and potent metabotropic glutamate (mGlu)5 receptor antagonist with inverse agonist activity. Fenobam was previously investigated as an anxiolytic in a number of phase II studies in the early 1980s. These studies revealed a mixed picture of anxiolytic efficacy, with double blind, placebo controlled trials variously reporting the compound as active or inactive. This discrepancy was not easily reconciled based on patient numbers, dose level, duration of treatment, or outcome measures. The positive effects seen in animal models of fragile X syndrome (FXS) treated with fenobam or other mGluR5 antagonists, the apparent lack of clinically significant adverse effects, and the potential beneficial clinical effects seen in this pilot trial support further study of the compound in adults with FXS.

Picenadol is a 4-phenylpiperidine derivative and a racemic mixture whose mixed agonist-antagonist properties are a consequence of the d-isomer being a potent opiate agonist, whereas the I-isomer is an opioid antagonist. In the mouse writhing and rat tail heat tests, the analgesic potency of picenadol is estimated to be 1/3 that of morphine. Picenadol itself has weak antagonist activity, whereas the antagonist potency of the l-isomer is approx. 1/10 that of nalorphine. Picenadol has high affinity for both the mu and delta receptors but a markedly lower affinity for the kappa receptor. Extensive pharmacological investigations show picenadol to have a low potential to produce opiate-like side effects, including a low liability for abuse and physical dependence. Antinociceptive properties of picenadol arise from mu agonist actions of the dextrorotatory isomer and that the levorotatory isomer acts to limit the efficacy of the racemate.

Tiapamil (also known as Ro 11-1781) is a dithiane derivative patented by Hoffmann-La Roche, F., und Co., A.-G. as calcium-channel antagonist useful for myocardial infarction treatment. Tiapamil, like verapamil, inhibited in a concentration-dependent manner Ca2+-induced contractions in isolated, K+-depolarized preparations of rat renal artery, dog coronary artery and rabbit main pulmonary artery. The inhibitory effects of Tiapamil can be overcome by raising the Ca2+ concentration of the bath fluid. In the rabbit main pulmonary artery, Tiapamil reduces 45Ca influx into the K+-depolarized vascular smooth muscle cells. Tiapamil inhibits the slow potentials in partially depolarized guinea-pig papillary muscles. Tiapamil decreases contractile force in isolated guinea-pig atria and papillary muscles, as well as in isolated cat hearts. Tiapamil also reduces heart rate and increases coronary flow in these preparations. Tiapamil doubled coronary artery blood flow in the coronary sinus blood without producing major changes in blood pressure and heart rate in anesthetized dogs. Tiapamil did not affect contractions of isolated guinea-pig ileum, rat stomach strips or rat vas deferens in response to various stimulants. Tiapamil have no major effects on renal water and electrolyte excretion, on autonomic nerves and receptors, on pain perception and on the central nervous system. Acute, subacute, and chronic toxicity studies demonstrate low toxicity for Tiapamil with no tendency for accumulation. In clinical trials, Tiapamil effectively lowers systolic and diastolic blood pressure, but have no effects on heart rate

Ethoxazene (2,4-diamino-4-ethoxyazobenzene) is an analgesic compound. It may be used as an indicator of acidity in an examination of gastric function.

Cloperidone is a quinazolinedione derivative with sedative and antihypertensive properties. Cloperidone was discovered in 1965 by Miles Laboratories. The activity of the compound was demonstrated by behavioral observations in dogs and cats, by rotarod and activity cage experiments in mice and in other models.

Diacetolol is the major metabolite of the β-adrenoceptor blocking agent, acebutolol. In vitro, the β-adrenoceptor blocking potency of diacetolol was less than that of acebutolol but its cardioselectivity (atrial relative to tracheal tissue) was greater. Diacetolol had weak intrinsic sympathomimetic activity, and no significant membrane-stabilizing activity. It did not restore sinus rhythm to anaesthetized dogs with ouabain-induced arrhythmias but was similar to acebutolol in preventing arrhythmia induced by adrenaline/methylchloroform in anaesthetized cats. Study of diacetolol pharmacokinetics and bioavailability suggests either a first-pass effect or incomplete absorption of diacetolol after oral administration. Diacetolol plasma half-life after oral administration is about 12 h and is not dose-dependent. Diacetolol possesses significant antihypertensive action against moderate essential hypertension in man. Its antihypertensive effect is associated with a reduction in the heart rate and a decrease in plasma renin activity.

Phenarsone sulfoxylate (Aldarsone), a pentavalent arsenical, is a condensation product of 3-amino-4 hydroxylphenylarsonic acid with sodium formaldehyde sulfoxylate. It is an antiamoebic agent. Aldarsone has a spirochetal power superior to that of tryparsamide. Aldarsone may be used in conjunction with artificial fever therapy and penicillin therapy to improve the results in symptomatic syphilis of the central nervous system (neurosyphilis).