FLUMEZAPINE, a benzodiazepine derivative, is an antipsychotic agent. It is a potent blocker of dopamine D2 and of some serotonin receptors. Its clinical development was dropped due to toxicology concerns.

Tetrahydrocannabivarin is a propyl analogue of tetrahydrocannabinol that acts as a Cannabinoid receptor type 1 antagonist and a partial agonist of Cannabinoid receptor type 2. Beyond the endocannabinoid system, Tetrahydrocannabivarin has also been reported to activate 5HT1A receptors to produce an antipsychotic effect that has therapeutic potential for ameliorating some of the negative, cognitive and positive symptoms of schizophrenia. Animal studies have shown that, like rimonabant, Tetrahydrocannabivarin reduces weight gain and food consumption in non-fasted mice but does not increase activity in the brain regions involved in emotion regulation. In another study, involving diet-induced obese mice, oral Tetrahydrocannabivarin reduced body fat content, increased energy expenditure, and reduced fasting insulin and 30-min insulin response to oral glucose tolerance test. In clinical trials THCV significantly decreased fasting plasma glucose and improved pancreatic β-cell function.

Elantrine is an anticholinergic drug. Elantrine has been investigated in the treatment of parkinsonism.

Harmine (aka telepathine) is a fluorescent harmala alkaloid belonging to the beta-carboline family of compounds. It is a naturally occurring metabolite in a number of plants, notably the Middle Eastern plant harmal or Syrian rue (Peganum harmala) and the South American vine Banisteriopsis caapi. Harmine is a reversible inhibitor of monoamine oxidase A (MAO-A), but not MAO-B. Harmine has been found to have potential anti-cancer and neuroprotective properties, and also promotes differentiation of osteoblasts and chondrocytes while inhibiting osteoclastogenesis. Harmine has also been used as a C-11 labeled probe in positron emission tomography.

Rose Bengal lactone is a polyhalogenated derivative of Fluorescein. Rose Bengal lactone is a dye compound described to produce cell membrane damage. Rose Bengal lactone and other Fluorescein derivatives are also described to modulate the function of ATP-sensitive K+ channels. Rose bengal lactone reacts readily with bases so treatment with triethylamine immediately yields the Rose Bengal salt.

Cartazolate (also known as SQ-65,396) is GABAA receptor positive allosteric modulator with potent anxiolytic activity proven in clinical trials. Cartazolate is also known to act as an adenosine antagonist at the A1 and A2 subtypes and as a phosphodiesterase inhibitor.

Diftalone is a symmetrical tetracyclic compound with anti-inflammatory and antipyretic activities. The anti-inflammatory potency of diftalone is greater than that of aspirin, approximately equal to that of phenylbutazone, but lower than that of indomethacin. Diftalone exhibited limited but statistically significant antipyretic activities. It less potent than aspirin or phenylbutazone. Diftalone seems to be an effective and safe anti-inflammatory agent in the treatment of rheumatoid arthritis. It demonstrated the same activity as indomethacin and phenylbutazone. However, because of hepatotoxicity and carcinogenicity (hepatoma) in preclinical studies and hemotoxicity and gastrointestinal adverse effects in humans, diftalone was withdrawn by its manufacturer.

Berythromycin or erythromycin B (also known as 12-deoxyerythromycin A), an acid-stable co-metabolite of the antibiotic erythromycin A, exhibits broad-spectrum antibiotic activity. The antibacterial activity of erythromycin B is similar to that of erythromycin A, but after acid-treatment, resembling exposure to the stomach, erythromycin B substantially retains antibacterial activity, whereas erythromycin A does not. Erythromycin B played an integral part of the structure activity relationship studies of semi-synthetic erythromycins.