m-Chlorophenylpiperazine (meta-chlorophenylpiperazine or mCPP) is a psychoactive substance, which is illegal in many countries but can be found on the black market. It induces endocrine, neurological and psychiatric effects. mCPP is a partial agonist at the 5-HT2C receptor but antagonized the 5-HT2B and 5-HT3 receptors. mCPP is also an active metabolite of the drug trazodone, which is used as an effective antidepressant drug with a broad therapeutic spectrum, including anxiolytic efficacy. It is known, that mCPP induces migraine attacks and that the decrease of food intake induced by the mCPP depends on its ability to act as a serotonin agonist is a brain.

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.

Doxpicomine is the hydrochloride salt of l-3[(dimethylamino)-(m-dioxan-5-yl)methyl]pyridine, a derivative of substituted 1,3 dioxanes. Its analgesic effect appears to be mediated centrally through opiate-like receptors. Preclinical animal studies revealed analgesic activity and duration of action of the same order as that of meperidine and codeine when administered subcutaneously and of codeine but of shorter duration when administered orally. The analgesic effects were reversed by naloxone. The drug did not reduce or antagonize the analgesic effect of morphine. Drowsiness is an expected response to effective analgesics. It was the foremost side effect observed but was of short duration and minimal intensity and did not interfere with the postoperative regimen of coughing, deep breathing, and early ambulation. Nausea and vomiting were not reported after doxpicomine.

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.