Mecysteine is used as a mucolytic in respiratory disorders associated with productive cough. Mecysteine is known as a mucolytic agent, it breaks down mucus. It works by breaking some of the chemical bonds between the molecules in mucus. It is given orally in a usual dose of 200 mg three times daily before meals reduced to 200 mg twice daily after 6 weeks. A rapid clinical effect can be achieved by giving 200 mg four times daily for the first 2 days. Mecysteine has also been given by inhalation.

The anticholinergic agent Flutropium is a classic competitive antagonist of acetylcholine. In in vitro experiments it is more effective than atropine. A poor enteral absorption is to be expected; this can be concluded from the low relative effectiveness after oral administration. After local administration as an aerosol it is superior to atropine with regard to both effectiveness and duration of action. It is used in Japan to treat asthma and chronic obstructive pulmonary disease. Flutropium can be described as a preparation which is free of side effects.

Trimetoquinol hydrochloride dilates bronchial muscle selectively by stimulating Beta 2-receptors. It is used for the relief of bronchoconstriction associated with bronchitis, asthmatic bronchitis and bronchial asthma. Since the concurrent use of the drug with catecholamines such as Epinephrine and Isoproterenol may induce arrythmia or cardiac arrest in some cases, concurrent use is not recommended. Adverse reactions : Palpitation may occur occasionally, and alteration of blood pressure and precordial pain may appear rarely; headache may occur occasionally; tremor, dizziness, feverish sensation may also be encountered in a rare incidence; occasionally, nausea and anorexia may appear.

Zinterol (MJ-9184-1) is an beta-adregenrgic agonist demostrated activity toward beta1-3 receptors. Oral zinterol caused a fast-appearing and long-lasting bronchodilator effect in patients with with stable chronic obstructive lung disease, however it seems development of zinterol was discontitued.

Ambroxol, a substituted benzylamine, is an active metabolite of bromhexine, which is itself a synthetic derivative of vasicine, the active principle extracted from the plant species Adhatoda vasica. Ambroxol is an expectorant exerting mucokinetic properties, mucociliary activity, stimulation of surfactant production, anti-inflammatory and antioxidative actions and the local anaesthetic effect. Ambroxol was discovered at and has been manufactured by Dr. Karl Thomae GmbH, a division of Boehringer Ingelheim. The ambroxol patent is expired and the drug is available as a generic product from many different companies. Ambroxol was originally developed by Boehringer Ingelheim as a OTC therapy for respiratory disorders related to excessive mucus. Ambroxol's indication is secretolytic therapy in acute and chronic bronchopulmonary diseases associated with abnormal mucus secretion and impaired mucus transport. Boehringer Ingelheim markets the product under various brand names such as Mucosolvan® and Lasolvan®. Ambroxol was identified and found to be a pH-dependent, mixed-type inhibitor of glucocerebrosidase (GCase). Its inhibitory activity was maximal at neutral pH, found in the endoplasmic reticulum, and undetectable at the acidic pH of lysosomes. The pH dependence of Ambroxol to bind and stabilize the enzyme was confirmed. Ambroxol increases both the lysosomal fraction and the enzymatic activity of several mutant GCase variants. This profile of Ambroxol would allow to bind and stabilize GCase in the endoplasmic reticulum (thus preventing its degradation within endoplasmic reticulum), but without affecting GCase in the lysosomes (thus allowing it to degrade glucosylceramide). Indeed, studies showed that Ambroxol treatment significantly increased N370S and F213I mutant GCase activity and protein levels in fibroblasts originally obtained from Gaucher patients. Gaucher's disease is caused by the deficiency of glucocerebrosidase; ambroxol is a chaperone that acts by binding to and stabilising glucocerebrosidase. Zywie (formerly ExSAR Corporation) and Belrose Pharma are developing ambroxol hydrochloride (BEL 0218) for the treatment of type III Gaucher's disease. .

Cilomilast (Ariflo) is an oral selective phosphodiesterase (PDE) IV inhibitor under development by GlaxoSmithKline Pharmaceuticals for treatment of COPD. After the demise of Merck's PDE-IV inhibitor (licensed from Celltech Group) in April 2003, Ariflo has emerged as the frontrunner in this new class of agents for inflammatory airways diseases, such as COPD. GlaxoSmithKline filed for drug approval with the US FDA at the end of 2002 and in January 2003 with the European Medicines Evaluation Agency (EMEA). In October 2003 the FDA issued an approvable letter for use of Ariflo in maintenance of lung function in COPD patients poorly responsive to salbutamol, despite an earlier decision by the FDA advisory panel to reject approval. Cilomilast shows high selectivity for cAMP-specific PDE4, an isoenzyme that predominates in pro-inflammatory and immune cells and that is 10-fold more selective for PDE4D than for PDE4A, -B or -C. In vitro, cilomilastsuppresses the activity of several pro-inflammatory and immune cells that have been implicated in the pathogenesis of asthma and COPD. Moreover, it is highly active in animal models of these diseases. Cilomilast has been shown to exert potent anti-inflammatory effects both in vitro and in vivo.

Etofylline [7-(2-hydroxyethyl)theophylline] is a N-7-substituted derivative of theophylline, a smooth muscle relaxant. Etofylline is used to relieve bronchoconstriction. It may act as a phosphodiesterase inhibitor and adenosine receptor antagonist.

Tulobuterol is a long-acting beta2-adrenergic receptor agonist. Tulobuterol has almost no effects on blood pressure and heart rate and is highly selective for the tracheal muscle. It is indicated to improve symptoms such as respiratory distress caused by airway obstruction of bronchial asthma, bronchitis, chronic obstructive pulmonary disease (COPD) and emphysema. Serious side effects detected were: tremor, palpitations and serum potassium level decrease.

Revefenacin (trade name Yupelri is a long-acting muscarinic antagonist developed by Mylan Ireland ltd for the treatment of chronic obstructive pulmonary disease (COPD). It has similar affinity to the subtypes of muscarinic receptors M1 to M5. In the airways, it exhibits pharmacological effects through inhibition of M3 receptor at the smooth muscle leading to bronchodilation. The competitive and reversible nature of antagonism was shown with human and animal origin receptors and isolated organ preparations. In preclinical in vitro as well as in vivo models, prevention of methacholine- and acetylcholine-induced bronchoconstrictive effects was dose-dependent and lasted longer than 24 hours.

Olodaterol is a beta2-adrenoceptor agonist discovered by Boehringer Ingelheim and approved for the treatment of Chronic Obstructive Pulmonary Disease. The compound exerts its pharmacological effects by binding and activation of beta2-adrenoceptors after inhalation. Activation of these receptors in the airways results in a stimulation of intracellular adenyl cyclase, an enzyme that mediates the synthesis of cyclic-3’, 5’ adenosine monophosphate (cAMP). Elevated levels of cAMP induce bronchodilation by relaxation of airway smooth muscle cells. Olodaterol effect lasts for 24 hours.