Dilevalol, the RR-stereoisomer of labetalol, is a non-cardioselective β-adrenoceptor antagonist with substantial partial β2-agonist and negligible α1-blocking activity. Reduction in blood pressure during dilevalol administration is associated with peripheral vasodilatation, and heart rate remains essentially unchanged. Following oral administration, dilevalol is completely absorbed. Once-daily administration is possible, due to a long elimination half-life. In vitro and in vivo animal studies and results obtained in humans reveal that dilevalol is a nonselective blocker of β1- and β2-adrenoceptors, with a similar potency to propranolol, but has negligible antagonistic activity at α1-receptors. Dilevalol, the R,R′ stereoisomer, makes up 25% of racemic labetalol, the drug, approved by FDA for the treatment of hypertension. The relaxing potency of dilevalol was approximately 4.7 times more potent than that of labetalol. Dilevalol markedly reduced the diastolic blood pressure with only a slight increase of heart rate In pithed rats, while isoproterenol and pindolol caused moderate to marked positive chronotropic effects in proportion to their hypotensive effects. These results suggest that dilevalol has more potent ISA than labetalol. In contrast to labetalol, dilevalol possesses little, if any, alpha-adrenergic blocking activity. The compound is 3 to 10 times less potent than labetalol at α1-adrenergic receptors under a variety of experimental conditions. Moreover, it is 300- to 1000-fold less potent at alpha1-adrenergic receptors compared with β1-adrenergic receptors. The pA2 values for dilevalol as an α antagonist range from 5.9 to 6.4. Because maximal plasma concentrations of the drug after administration of a 400-mg dose are approximately 0.5 pmol, it is doubtful that alpha blockade is involved in the antihypertensive response to dilevalol in humans.

Adatanserin is an adamantyl piperazine derivative a partial agonist of 5-HT1A receptors and antagonist of 5-HT2A and 5-HT2C receptors. Adatanserin demonstrated activity in vivo in rat serotonin syndrome, quipazine- and DOI-induced head shake experiments, and anxiolytic activity in animal conflict model. It was developed by Wyeth for the treatment of depression. The compound was investigated in phase II clinical trials in anxiety disorders and major depressive disorders, but no results were reported, and the development of adatanserin was discontinued.

Amperozide (FG 5606, N-ethyl-4-[4',4'-bis(p-fluorophenyl)butyl]-1-piperazine-carboxamide) is an atypical antipsychotic drug which has relatively weak in vitro affinity for striatal dopamine2 (D2) receptors and a strong affinity for the cortical 5-HT2A receptor. It was shown in animal models, that amperozide could attenuate craving for cocaine. In addition, this drug was studied in patients with schizophrenia and was shown, that several patients had improvements as was assessed by the Clinical Global Improvement Scale. However, these studies were discontinued.

Raclopride is a salicylamide neuroleptic, that acts as a selective antagonist of D2 dopamine receptors both in vitro and in vivo. Tritium-labelled raclopride has properties that demonstrate its usefulness as a radioligand for the labelling of dopamine-D2 receptors : 3H-Raclopride has a high affinity for the rat and human dopamine-D2 receptors, the non-specific binding of 3H-raclopride is very low, not exceeding 5% of the total binding and the distribution of the 3H-raclopride binding sites in the brain closely correlates with the dopaminergic innervation. The binding of 3H-raclopride is blocked by dopamine-D2 agonists and antagonists, while the D1 agonist SKF 38393 and the Dl antagonist SCH 23390 have much less potency. The interaction of dopamine with 3H-raclopride binding results in a shallow competition curve, which suggests that 3H-raclopride, similar to other dopamine-D2 radioligands, labels both high and low agonist affinity states of the dopamine-D2 receptor. The in vivo receptor binding studies performed with 3H-raclopride also demonstrate its favorable properties as a dopamine-D2 receptor marker in vivo In contrast to some other compounds used as radioligands, raclopride enters the brain readily and binds with a low component of non-specific binding in all dopamine-rich brain areas. A saturation curve may be achieved in vivo binding studies since injections of increasing concentrations of 3H-raclopride appears to be saturated at concentrations above 25 mkCi (corresponding to approximately 5 nmol/kg). Raclopride antagonizes apomorphine-induced hyperactivity in the rat at low doses (ED50 = 130 nM/kg i.p.) but induces catalepsy only at much higher doses (ED50 = 27 mkM/kg i.p.). Radiolabelled raclopride has been used as a ligand for in vitro and in vivo autoradiography in rat and primate brains. Raclopride C 11 is used with positron emission tomography (PET) as a clinical research tool to determine dopamine type 2 (D 2) receptor density in the human brain under normal and pathological conditions. For example, raclopride C 11 used in PET studies has served to confirm the age-related decrease in striatal dopamine D2 receptor density, which may be associated with a decline in the motor as well as cognitive functions. In patients with Alzheimer's disease, raclopride C 11 may be used to examine neuroreceptor distribution and quantities, which may help in the analysis of degenerative alterations of neuron populations and neuroreceptor systems in patients with this disease. In Huntington's disease, in which degeneration of neostriatal interneurons occurs (postsynaptic to the dopaminergic input), specific binding of raclopride C 11 to D 2 receptors may serve as one of the parameters in predicting performance in cognitive tasks.

Oxitropium bromide (trade names Oxivent, Tersigan) is a bronchodilator indicated for asthma and chronic obstructive pulmonary disease. Oxitropium’s bronchodilation effect is similar to that of ipratropium bromide, but oxitropium is longer-lasting. The usual dose is 200 ug, 2–3 times daily. It blocks the muscarinic cholinergic receptors which mediate smooth muscle contraction in the airways. The manufacturer claims that regular use of oxitropium (200μg twice or three times daily) reduces the incidence of symptoms, including the need for night-time bronchodilators, and improves lung function in some patients; it is not intended for immediate symptom relief. Although widely used for many years (alone or in combination with short-acting beta agonists) for both maintenance treatment of stable disease and exacerbation of airway obstruction, Boehringer Ingelheim announced the discontinuation of Oxivent formulations at May 2004.

Camylofin is an antimuscarinic. This medication is used as antispasmodic in biliary colic, renal and ureteric colic, dysmenorrhoea, peptic ulcer and chronic enterocolitis. It is used to treat stomach ache in infants and children. Camylofin should be the first choice and may be preferred over other drugs for cervical dilatation and acceleration of active phase of labor.

Ramatroban is a dual antagonist of thromboxane A2 receptor and PGD2 receptor. The drug was developed by Bayer and tested for the treatment of asthma and allergic rhinitis. In Japan ramatroban reached final approval and is being marketed under the name Baynas. In vitro studies have shown that the drug effectively inhibits smooth muscle cells contraction.

Benzilonium is an antispasmodic and antimuscarinic drug. Benzilonium bromide is a quarternary antimuscarinic agent with minimal passage of the blood-brain barrier.

Acefylline is a stimulant drug of the xanthine chemical class. It acts as an adenosine receptor antagonist. Acephylline piperazine is a theophylline derivative with a direct bronchodilator action. It has the advantages over theophylline in being far less toxic and producing minimal gastric irritation. It is indicated for the treatment of asthma, emphysema, acute and chronic bronchitis associated with bronchospasm.Acefylline relaxes smooth muscles, relieves bronchospasm & has a stimulant effect on respiration. It stimulates the myocardium & central nervous system, decreases peripheral resistance & venous pressure & causes diuresis. The mechanism of action is still not clear, inhibition of phosphodiesterase with a resulting increase in intracellular cyclic AMP does occur, but not apparently at concentrations normally used for clinical effect. Other proposed mechanisms of action include adenosine receptor antagonism, prostaglandin antagonism & effects on intracellular calcium. Sodium phenobarbital is a non-selective central nervous system depressant that is primarily used as sedative-hypnotic.

Acecainide (N-acetylprocainamide), the N-acetylated metabolite of procainamide, is a Class III antiarrhythmic agent. Acecainide exerts cardiac anticholinergic effect. It elicits smooth muscle relaxation mainly through the activation of plasma membrane K+ channels. Acecainide markedly reduced premature ventricular beats and prevented induction of ventricular tachycardia. Acecainide appears to offer advantages over procainamide, particularly with respect to the reduced formation of antinuclear antibodies. Acecainide development has been discontinued.