A centrally acting skeletal muscle relaxant whose mechanism of action is not completely understood but may be related to its sedative actions. Carisoprodol is indicated for the relief of discomfort associated with acute, painful musculoskeletal conditions in adults. Most common adverse reactions (incidence > 2%) are drowsiness, dizziness, and headache. Carisoprodol might be mixtured with Aspirin and Codeine Phosphate. Studies indicating increased risk of abuse or addiction led to withdrawal of the drug from the market in Norway and other EU countries in 2008.

Isocarboxazid (Marplan, Marplon, Enerzer) is a non-selective, irreversible monoamine oxidase inhibitor (MAOI) of the hydrazine class used as an antidepressant. In vivo and in vitro studies demonstrated inhibition of MAO in the brain, heart, and liver. Depression is a complicated disease that is not fully understood. It is thought that depression may be linked to an imbalance of chemicals within the brain. When depression occurs, there may be a decrease in the amount of chemicals released from nerve cells in the brain. These chemicals are called monoamines. Monoamines are broken down by a chemical called monoamine oxidase. Isocarboxazid prevents monoamine oxidase from breaking down the monoamines. This results in an increased amount of active monoamines in the brain. By increasing the amount of monoamines in the brain, the imbalance of chemicals thought to be caused by depression is altered. This helps relieve the symptoms of depression. Isocarboxazid works by irreversibly blocking the action of a chemical substance known as monoamine oxidase (MAO) in the nervous system. MAO subtypes A and B are involved in the metabolism of serotonin and catecholamine neurotransmitters such as epinephrine, norepinephrine, and dopamine. Isocarboxazid, as a nonselective MAO inhibitor, binds irreversibly to monoamine oxidase–A (MAO-A) and monoamine oxidase–B (MAO-B). The reduced MAO activity results in an increased concentration of these neurotransmitters in storage sites throughout the central nervous system (CNS) and sympathetic nervous system. This increased availability of one or more monoamines is the basis for the antidepressant activity of MAO inhibitors. May be used to treat major depressive disorder.

Tropicamide (Mydriacyl) is an anticholinergic used as a mydriatic.Tropicamide belongs to the group of medicines called anti-muscarinics. Tropicamide blocks the receptors in the muscles of the eye (muscarinic receptors). These receptors are involved controlling the pupil size and the shape of the lens. By blocking these receptors, tropicamide produces dilatation of the pupil (mydriasis) and prevents the eye from accommodating for near vision (cycloplegia). Tropicamide is given as eye drops to dilate the pupil and relax the lens so that eye examinations can be carried out thoroughly.

Chlorzoxazone is a centrally acting central muscle relaxant with sedative properties. It is claimed to inhibit muscle spasm by exerting an effect primarily at the level of the spinal cord and subcortical areas of the brain where it inhibits multisynaptic reflex arcs involved in producing and maintaining skeletal muscle spasm of varied etiology. The clinical result is a reduction of the skeletal muscle spasm with relief of pain and increased mobility of the involved muscles. Chlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.

Perphenazine is a relatively high potency phenothiazine that blocks dopamine 2 receptors predominantly, but also may possess antagonist actions at histamine 1 and cholinergic M1 and alpha 1 adrenergic receptors in the vomiting center leading to reduced nausea and vomiting. The drug was approved by FDA for the treatment of schizophrenia and control of severe nausea and vomiting (either alone or in combination with amitriptyline hydrochloride). Perphenazine is extensively hepatic to metabolites via sulfoxidation, hydroxylation, dealkylation, and glucuronidation; primarily metabolized by CYP2D6 to N-dealkylated perphenazine, perphenazine sulfoxide, and 7-hydroxyperphenazine (active metabolite with 70% of the activity of perphenazine) and excreted in the urine and feces.

Orphenadrine is an anticholinergic drug of the ethanolamine antihistamine class used to treat muscle pain and to help with motor control in Parkinson's disease but has largely been superseded by newer drugs. Orphenadrine binds and inhibits both histamine H1 receptors and NMDA receptors. It restores the motor disturbances induced by neuroleptics, in particular, the hyperkinesia. The dopamine deficiency in the striatum increases the stimulating effects of the cholinergic system. This stimulation is counteracted by the anticholinergic effect of orphenadrine. It may have a relaxing effect on skeletal muscle spasms and it has a mood elevating effect. Orphenadrine is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute painful musculoskeletal conditions. Orphenadrine is an anticholinergic with a predominantly central effect and only a weak peripheral effect. In addition, it has mild antihistaminic and local anesthetic properties. Parkinson's syndrome is the consequence of a disturbed balance between cholinergic and dopaminergic neurotransmission in the basal ganglia caused by a decrease in dopamine. Orphenadrine restores the physiological equilibrium and has a favorable effect on the rigidity and tremor of Parkinson's disease and Parkinsonian syndromes. Adverse reactions of orphenadrine citrate are mainly due to the mild anticholinergic action of orphenadrine citrate and are usually associated with higher dosage. Dryness of the mouth is usually the first adverse effect to appear. When the daily dose is increased, possible adverse effects include tachycardia, palpitation, urinary hesitancy or retention, blurred vision, dilatation of pupils, increased ocular tension, weakness, nausea, vomiting, headache, dizziness, constipation, drowsiness, hypersensitivity reactions, pruritus, hallucinations, agitation, tremor, gastric irritation and rarely urticaria and other dermatoses

Mesuximide (or methsuximide) is an anticonvulsant medication. It is sold by Pfizer under the name Petinutin. Binds to T-type voltage sensitive calcium channels. Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. The isoform alpha-1G gives rise to T-type calcium currents. T-type calcium channels belong to the "low-voltage activated (LVA)" group and are strongly blocked by mibefradil. A particularity of this type of channels is an opening at quite negative potentials and a voltage-dependent inactivation. T-type channels serve pacemaking functions in both central neurons and cardiac nodal cells and support calcium signaling in secretory cells and vascular smooth muscle. They may also be involved in the modulation of firing patterns of neurons which is important for information processing as well as in cell growth processes. Mesuximide is used for the control of absence (petit mal) seizures that are refractory to other drugs.

Mecamylamine (Inversine), the first orally available antihypertensive agent, is now rarely used. Introduced as a therapeutic agent for the treatment of hypertension in the 1950s, mecamylamine was the first useful ganglionic blocking agent that was not a quarternary ammonium compound. Mecamylamine is indicated for the management of moderately severe to severe essential hypertension and in uncomplicated cases of malignant hypertension. Mecamylamine reduces blood pressure in both normotensive and hypertensive individuals. A small oral dosage often produces a smooth and predictable reduction of blood pressure. Although this antihypertensive effect is predominantly orthostatic, the supine blood pressure is also significantly reduced. Mecamylamine is a nicotinic parasympathetic ganglionic blocker. Mecamylamine administration produces several deleterious side-effects at therapeutically relevant doses. As such, mecamylamine’s use as an antihypertensive agent was phased out, except in severe hypertension. Mecamylamine easily traverses the blood-brain barrier to reach the central nervous system (CNS), where it acts as a nicotinic acetylcholine receptor (nAChR) antagonist, inhibiting all known nAChR subtypes. Since nAChRs play a major role in numerous physiological and pathological processes, it is not surprising that mecamylamine has been evaluated for its potential therapeutic effects in a wide variety of CNS disorders, including addiction.

Prochlorperazine is a piperazine phenothiazine antipsychotic which block postsynaptic mesolimbic dopaminergic receptors in the brain and has antiemetic effects by its antagonist actions in the D2 dopamine receptors in the chemoreceptor trigger zone. It also exhibits alpha-adrenergic blocking effect on α1 receptros and may depress the release of hypothalamic and hypophyseal hormones. Prochlorperazine is used for the control of severe nausea and vomiting, for the treatment of schizophrenia. Prochlorperazine is effective for the short-term treatment of generalized non-psychotic anxiety. Prochlorperazine may be an effective treatment of acute headaches and refractory chronic daily headache.

Hydroxyzine, a piperazine antihistamine structurally related to buclizine, cyclizine, and meclizine, is used to treat histamine-mediated pruritus or pruritus due to allergy, nausea and vomiting, and, in combination with an opiate agonist, anxiolytic pain. Hydroxyzine is also used as a perioperative sedative and anxiolytic and to manage acute alcohol withdrawal. Hydroxyzine competes with histamine for binding at H1-receptor sites on the effector cell surface, resulting in suppression of histaminic edema, flare, and pruritus. The sedative properties of hydroxyzine occur at the subcortical level of the CNS. Secondary to its central anticholinergic actions, hydroxyzine may be effective as an antiemetic. It is used for symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states in which anxiety is manifested.