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A pump is a utility that moves a substance against a gradient. A well known example is the water pump which lifts water up against gravity. In our case, there are cells in the membrane lining the stomach lumen, these cells produce acid and pump it against the concentration gradient set by the previously formed acid into the stomach lumen. That means the concentration of acid in the stomach lumen is higher than that inside the cell and this gradient would favor movement of acid into the cell; however the cellular wall prevents this and at the same time pumps more acid into the lumen. Just like the water pump needs electric energy to lift water upwards; the cellular wall utilizes chemical energy to pump acid outwards.
Acid or Proton Pump?
Acid is produced in the form of a positively charged subatomic particle called proton. The proton is the nucleus of the lightest chemical element, hydrogen . Actually the hydrogen atom consists of a proton as the nucleus, to which a negatively charged single electron is bound as opposite charges attract. Because the proton is 1836 times heavier than the electron, the proton is considered to constitute almost the entire mass of the hydrogen atom.
So how proton pump inhibitors affect this mechanism?
They accumulate on the luminal surface of the acid producing cells and inhibit the enzymes involved in the process of synthesis of chemical energy , essential for the pumping action. Consequently; no energy, no pump activity and no acid production (no proton flow into the lumen of the stomach). At a cellular level there are receptor sites at which signals triggering acid secretion interact. These triggers are Histamine, Gastrin and Acetylcholine. They are chemical substances delivered around acid producing cells and are released from local cells, intestinal cells or nerve endings.
Examples of Proton Pump Inhibitors include: Omeprazole (Prilosec) Lansoprazole (Prevacid) Rabeprazole (Aciphex) Pantaprazole (Protonix) Esomeprazole (Nexium) Proton Pump Inhibitors are used for both diagnosis and treatment. In the diagnostic Omeprazole test: a dose of 40mg is given in the morning and another 20mg in the evening for 7days to a heartburn sufferer. If symptoms are relieved following this regimen, the diagnosis of acid reflux is confirmed. It is considered a noninvasive and easily available test with reasonable cost.
For acid reflux relief, they are considered the most effective therapeutic agents and the standard medication. All of them are effective but response may vary from person to person. Proper timing of intake is critical for efficacy, it should be 30minutes before breakfast or other large meal. For some patients with partial response or severe symptoms, the physician may advice a second additional dose before the evening meal. Being long acting (duration of action of a single dose is 24hours), they allow time for damaged tissues to heal. They have a healing rate of 80% in moderate to severe cases and relief of symptoms in up to 90% of patients. In comparison to Histamine type2 receptor antagonists, they are more effective and faster in promoting healing.