diazepam

Dental Use:
Orally, as a preoperative medication for dental anxiety. And as a skeletal muscle relaxant. The latter as part of the management in TMD (temporomandibular joint dysfunction). Also, as a sedative component in I.V. conscious sedation in oral surgery patients.

Medical use:
In the management of general anxiety disorders, panic disorders, and provide preoperative sedation, light anaesthesia, and amnesia; treatment of status epilepticus, alcohol withdrawal symptoms; used as a skeletal muscle relaxant.

Mechanism of action:
Depresses all levels of the CNS (central nervous system) through the release of GABA (gamma-aminobutyric acid). GABA is a major inhibitory neurotransmitter in the brain.

Drug Interactions:
CNS depressants, alcohol, disulfiram, cimetidine, anticonvulsants, anticholinergics.

Contraindications:
Hypersensitivity to diazepam or any component, pre-existing CNS depression, repiratory depression, narrow angle glaucoma, pregnant women. Precaution with concurrent CNS depressants, hepatic dysfunction, renal impairment, prolonged use and abrupt withdrawal.

With help from: Drug Information Handbook for Dentistry. Lexi-Comp's Clinical Reference Library.MIMS.

There seems to be an inverse correlation between intelligence and happiness implied here. But I doubt that is the fault of the chemical. Like all drugs it's use must be carefully controlled because of medical side effects, in this case addiction being the primary risk.