D.2.1

=**__ D2.1 State and explain how excess acidity in the stomach can be reduced by the use of different bases.__**=


 * Definition: What are Antacids?**[[image:antacids.jpg width="277" height="156" align="right" caption="http://www.irishhealth.com/clin/heartburn/overthecounter.html" link="http://www.irishhealth.com/clin/heartburn/overthecounter.html"]]
 * Antacids are basic medications which do not require a doctor's prescription for usage
 * Usually administered orally
 * Restores the pH balance in your stomach by neutralizing the Hydrochloric acid (HCl) of pH 1-2 in the stomach
 * Relieves symptoms of heartburn, indigestion and other stomach issues (e.g. sour and upset stomachs) when the pH level in your stomach is overly low (acidic)
 * They merely need to employ the use of weak bases
 * Must be taken occasionally, under proper circumstances, or may cause permanent damage to the heart, kidney or bones
 * Minor side effects include headaches and nausea. Side effects occur very rarely if the antacid is used moderately

Our stomach usually has a pH of around 2~3 because of the acidic environment. When the pH drops below that, we experience discomfort. An antacid is a base that will neutralize the excess acid to bring the pH level back to around 3~4.
 * How Do They Work?**

Examples are provided below.
 * [|Sodium Hydrogen-carbonate is one of the best known antacids. It is commonly known as baking soda and it acts extremely fast.] (Increased intake of sodium could cause heart failure and arterial hypertension - high blood pressure)
 * Equation: NaHCO3 + HCl → NaCl + H2O + CO2


 * **Aluminum** compounds usually include carbonate, hydroxide, or phosphate. (Could cause constipation)
 * Equation: Al(OH)3 + 3HCl → AlCl3 + 3H2O
 * **Magnesium** compounds can come in many forms, such as carbonate, hydroxide, oxide, trisilicate and aluminosilicate. (Has laxative(excrement-inducive) properties)
 * Equation: MgCO3 + 2HCl → MgCl2 + 2H2O
 * Equation: Mg(OH)2(s) + 2 HCl(aq) -> MgCl2(aq) + 2 H2O(l)
 * Two of the most commonly known calcium antacids are calcium carbonate and calcium phosphate.
 * Equation: CaCO3 + 2HCl → CaCl2 + H2O + CO2

Antacids containing **magnesium hydroxide** and **sodium bicarbonate** dissolve rapidly in the stomach and will therefore bring the fastest relief.
 * Differences in Antacids:**

Antacids containing **calcium carbonate** or **aluminum hydroxide** take longer to dissolve, however the antacid functions for a longer period of time.

When an antacid stays in the stomach for a long time or if it is taken after a meal, it will function for a longer period of time. In addition, the uses of alginates and **anti-foaming agents** are to **prevent damage of the stomach and esophageal linings.** By using alginates, which float on the acid layer, the stomach and parts of the esophagus are coated even in the event of acid reflux, creating another layer of protection.
 * Alginates & Anti-Foaming Agents!**
 * Anti-foaming agents work to prevent foam that would rise easier, and carry the stomach acid with it.** An additive which reduces the surface tension of a solution or emulsion, thus inhibiting or modifying the formation of a foam. Commonly used agents are insoluble oils, dimethyl polysiloxanes and other silicones, certain alcohols, stearates and glycols. The additive is used to prevent formation of foam or is added to break a foam already formed. As many reactions between antacids and hydrochloric acid result in the production of CO2, the anti-foaming agent is necessary to prevent vomiting which may be caused by the formation of a foam layer of gas in the stomach. Instead, the bubbles are broken and the gas rises as foam, which is what causes burping after taking particular types of antacids.

//NOTE: The altered pH due to antacids may affect the effects of other drugs that are taken oraly//

http://www.faqs.org/health/topics/50/Antacids.html