Quercetin is a unique bioflavonoid that has been extensively studied by researchers over the past 30 years. Quercetin, the most abundant of the flavonoids (the name comes from the Latin –quercetum, meaning oak forest, quercus oak) consists of 3 rings and 5 hydroxyl groups. Quercetin is a member of the class of flavonoids called flavonoles and forms the backbone for many other flavonoids including the citrus flavonoids like rutin, hesperidins, Naringenin and tangeritin. It is widely distributed in the plant kingdom in rinds and barks. The best described property of Quercetin is its ability to act as antioxidant. Quercetin seems to be the most powerful flavonoids for protecting the body against reactive oxygen species, produced during the normal oxygen metabolism or are induced by exogenous damage [9, 10]. One of the most important mechanisms and the sequence of events by which free radicals interfere with the cellular functions seem to be the lipid peroxidation leading eventually the cell death. To protect this cellular death to happen from reactive oxygen species, living organisms have developed antioxidant line of defense systems [11]. These include enzymatic and non-enzymatic antioxidants that keep in check ROS/RNS level and repair oxidative cellular damage. The major enzymes, constituting the first line of defence, directly involved in the neutralization of ROS/RNS are: superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) The second line of defence is represented by radical scavenging antioxidants such as vitamin C, vitamin A and plant phytochemicals including quercetin that inhibit the oxidation chain initiation and prevent chain propagation. This may also include the termination of a chain by the reaction of two radicals. The repair and de novo enzymes act as the third line of defence by repairing damage and reconstituting membranes. These include lipases, proteases, DNA repair enzymes and transferases. Quercetin is a specific quinone reductase 2 (QR2) inhibitor, an enzyme (along with the human QR1 homolog) which catalyzes metabolism of toxic quinolines. Inhibition of QR2 in plasmodium may potentially cause lethal oxidative stress. The inhibition of antioxidant activity in plasmodium may contribute to killing the malaria causing parasites.

Methoxyphenamine also known as 2-methoxy-N-methylamphetamine (OMMA), is a beta adrenergic receptor agonist nd is used as a bronchodilator to treat asthma, chronic obstructive pulmonary disease (COPD) and postinfectious cough. In addition, methoxyphenamine using is prohibited in sports according to the regulations of the World Anti-Doping Agency (WADA).

Clenbuterol is agonist of beta2 adrenergic receptor. In some countries it is used as bronchodilator for treatment of asthma, but is not approved in USA. The drug is abused by bodybuilders and athletes for its ability to increase lean muscle mass and to reduce body fat. In 1998 FDA approved the clenbuterol-based Ventipulmin Syrup as a prescription-only drug for treatment of airway obstruction in horses.

S-Carboxymethylcysteine (carbocysteine or SCMC; also available in the lysinate form, SCMC-Lys) is a mucoactive drug, has antioxidant and anti-inflammatory properties. Carbocysteine has been recently recognized as an effective and safe treatment for the long-term management of COPD, able to reduce the incidence of exacerbations and improve patient quality of life. Moreover, carbocysteine was effective in counteracting some symptoms associated with cancer cachexia. Preclinical and clinical studies have demonstrated that the antioxidant and anti-inflammatory properties of carbocysteine are more important than mucolysis itself for its therapeutic efficacy. Therefore, carbocysteine may be able to reverse the oxidative stress associated with several chronic inflammatory diseases, such as cardiovascular diseases and neurodegenerative disorders.

S-Carboxymethylcysteine (carbocysteine or SCMC; also available in the lysinate form, SCMC-Lys) is a mucoactive drug, has antioxidant and anti-inflammatory properties. Carbocysteine has been recently recognized as an effective and safe treatment for the long-term management of COPD, able to reduce the incidence of exacerbations and improve patient quality of life. Moreover, carbocysteine was effective in counteracting some symptoms associated with cancer cachexia. Preclinical and clinical studies have demonstrated that the antioxidant and anti-inflammatory properties of carbocysteine are more important than mucolysis itself for its therapeutic efficacy. Therefore, carbocysteine may be able to reverse the oxidative stress associated with several chronic inflammatory diseases, such as cardiovascular diseases and neurodegenerative disorders.

S-Carboxymethylcysteine (carbocysteine or SCMC; also available in the lysinate form, SCMC-Lys) is a mucoactive drug, has antioxidant and anti-inflammatory properties. Carbocysteine has been recently recognized as an effective and safe treatment for the long-term management of COPD, able to reduce the incidence of exacerbations and improve patient quality of life. Moreover, carbocysteine was effective in counteracting some symptoms associated with cancer cachexia. Preclinical and clinical studies have demonstrated that the antioxidant and anti-inflammatory properties of carbocysteine are more important than mucolysis itself for its therapeutic efficacy. Therefore, carbocysteine may be able to reverse the oxidative stress associated with several chronic inflammatory diseases, such as cardiovascular diseases and neurodegenerative disorders.

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.

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.

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. .

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.