Each drug has a specific molecular target in which it acts on. Some drugs have enzymes as their main molecular target by either activating or inhibiting them, whereas other drugs act on specific receptors (sensing elements). Other drugs act on ion channels which can be direct or indirect. Other types of drugs act on transporters (Carrier molecules). A specific molecular change takes place when a drug binds to its particular receptor.
The molecular changes lead to further changes in physiological or psychological functions. Some drugs act as agonists whereas some act as antagonists. Agonists bind to a particular receptor and initiate a cellular response however on the other hand antagonists do not initiate any biological response. Pharmcodynamics is the study of the physiological and biochemical interaction of drug molecules with the molecular target which triggers an effect.
Navispare (Cyclopenthiazide & Amiloride Hydrochloride) acts on the distal renal tubule in the kidney (sodium-chloride transporter). Navispare consists of the two active ingredients in which each of them has a particular function. Cyclopenthiazide is a thiazide diuretic which functions by inhibiting the reabsorption of sodium chloride and water at the distal renal tubule. This will therefore increase the amount of salts (Na+ + K+) and water filtered out of the blood. Reducing the water content in the body will then reduce the pressure.
Amiloride is a potassium-sparing diuretic which belongs to the pyrazine carboxamide class. The Amiloride also acts on the distal part of the rental tubule. It increases the excretion of sodium and chloride ions and reduces the excretion of potassium. This is to prevent losing too much potassium. Both active ingredients work together to ensure that the correct level of potassium is maintained while reducing the blood pressure. Navispare is used to treat hypertension.
MabThera (Rituximab) acts by binding to the surface of a type of white blood cell (B lymphocyte). Rituximab binds to the transmembrane antigen (CD20) which is a non-glycosylated phosphoprotein located on the pre-B and mature B lymphocytes. When Rituximab binds to the white blood cell, it causes it to die. MabThera is used to treat Rheumatoid arthritis and Non-Hodgkins lymphoma.
Zyban (Bupropion hydrochloride) acts by affecting neurotransmitters in the brain. Neurotransmitters are used in transmitting impulses from one nerve to another. Bupropion works by selectively inhibiting the neuronal reuptake of catecholamines (Noradrenaline + Dopamine). Noradrenaline and dopamine are the neurotransmitters responsible for moderating mood and other processes in the brain. Zyban is used to treat patients looking to quit smoking (with the aid of motivational support)
Singulair (Montelukast) acts by binding to leukotriene receptors in the human airway. Montelukast act as an antagonist by binding with high affinity and selectivity to leukotriene receptors. It functions by inhibiting the release of the chemicals produced by the body as part of allergic and inflammatory reactions. Release of leukotriene causes inflammation and mucous production in the airways, it also cause the muscles in the airways to contract, which narrows the airways. Montelukast prevents the airways to contract and mucous to be produced which prevents narrowing of the airways. Singulair is used to treat Asthma.
Avonex (Interferon Beta-1a) works by binding to specific receptors on the surface of the human cells. Interferon Beta-1a binds to specific receptors on the surface of human cells which triggers a complex cascade of intracellular events that lead to the expression of numerous interferons (which are induced gene products and markers). Avonex is used with patients diagnosed with relapsing sclerosis and also to patients with single demyelinating event with an active inflammatory process
Combivent (Salbutamol sulphate + Ipratropium bromine) functions by binding to acetylcholine receptors in the lungs. Ipratropium bromine is an antagonist that binds to acetylcholine. It inhibits vagally mediated reflexes due to the fact that it is an anticholinergic agent. The inhalation of the Ipratropium bromine causes bronchodilation which is local to the lungs and not systemic. Salbutamol sulphate is a beta2-adrenergic agent. It causes the relaxation of the airway smooth muscle. Both active ingredients in Combivent (Salbutamol sulphate + Ipratropium bromine) work together for a better a result. Combivent is used for the treatment of bronchospasm associated with chronic obstructive pulmonary disease.