PHARMACEUTICAL CHEM NOTES

PHARMACEUTICAL CHEMISTRY

Chapter 5 – Gastrointestinal Agents

• Inorganic agents used to treat gastrointestinal disorders includes:
1. Products for altering gastric pH
2. Protectives for intestinal inflammation
3. Adsorbents for intestinal toxins
4. Cathartics of laxatives for constipation

ANTACIDS o neutralize excess hydrochloric acid o inactivate the proteolytic enzyme, pepsin o alkaline bases
Results of Hyperacidity: o Gastritis – inflammation of the gastric mucosa o Peptic ulcer – specified circumscribed erosion
a. Duodenal ulcer – duodenum (perforation)
b. Gastric ulcer – stomach (malignancy & hemorrhage)
c. Esophageal ulcer – lower esophagus (heartburn)
Criteria for an antacid:
a. Should not be absorbable or cause systematic alkalosis
b. Should not be a laxative or cause constipation
c. Should exert rapid effect and should last long
d. Should not cause a large evolution of gas (flatulation)
e. Buffer range of 4 – 6 pH
f. Should inhibit pepsin

1. SODIUM BICARBONATE
Disadvantages:
• highly water soluble
• short duration of effect
• gastric pH of 7 or above
• can cause belching and flatulence
Benefits:
• sparkling flavor

2. ALUMINUM HYDROXIDE
Forms:
a. Aluminum Hydroxide Gel (suspension)
• contain aromatics and sweetening
• not more than 0.5% preservatives
b. Dried Aluminum Hydroxide Gel (powder)
• colloidial – great adsorptive powers
• amphoteric characters
Disadvantages:
• loss of antacid properties on aging
• causes constipation
• causes nausea and vomiting Uses:
• gastric antacid for hyperchlorhydria
• for intestinal toxemia

CALCIUM-CONTAINING ANTACIDS
• dependent upon their basic properties
• raise stomach pH to 7
• constipating
• found in combinations with magnesium antacids

1. CALCIUM CARBONATE
• precipitated chalk
• fast action
• found in combinations with Mg antacids
• in Lozenges and Oral suspension

2. TRIBASIC CALCIUM PHOSPHATE
• Precipitated Calcium Phosphate, Tertiary Calcium