Coating disintegration

Figure 4 shows the insulative ability of the above formulation. Three coats were applied over a primer to a total dry film thickness of 20 mils, allowing 24 hours dry time between coats. This graph indicates complete failure in 8 minutes. When subjected to other tests the coating lacked adhesion to metal, moisture resistance, and flexibility. After, puffing, the coating disintegrated under vibration. 

Some dmgs are more effective if absorbed in the small intestine rather than the stomach. However, the stomach is more acidic than the small intestine. Therefore, pharmaceutical manufacturers place an enteric coating around the dmg that resists disintegration in the stomach. The coating disintegrates in the alkaline environment of the small intestine. Enteric coating is also used to delay the onset of the pharmaceutical response and to prevent food in the stomach from interfering with the dissolution and absorption of the dmg. 

The normal visible deterioration of a paint coating is by the appearance of chalking on its surface. Chalking is the term used to denote the powdery material that appears as the binder slowly disintegrates and exposes the pigments. 

Features The rate of deposition is low compared with that of vacuum evaporation, and is affected by variables such as pressure and temperature of coating-chamber atmosphere, arc voltage, cathode current density and geometry of cathode and A/j. A high vacuum is not essential, particularly where an inert gas can be used. The A/, disintegration rate is affected by the atomic weight of coating-chamber gas. 

Oral administration of bicarbonate may decrease the absorption of ketoconazole. Increased blood levels of quinidine, flecainide, or sympatiiomimetics may occur when these agents are administered with bicarbonate There is an increased risk of crystalluria when bicarbonate is administered with the fluoroquinolones. Fbssible decreased effects of lithium, methotrexate, chlorpropamide, salicylates, and tetracyclines may occur when these drag s are administered with sodium bicarbonate. Sodium bicarbonate is not administered within 2 hours of enteric-coated drugs the protective enteric coating may disintegrate before the drug reaches the intestine. 

A drug should always be ingested with a cup of water ( 8 oz) to insure easy transit down the esophagus and to provide fluid for disintegration and dissolution. Whether or not the drug should be taken on an empty stomach (e.g., enteric-coated tablets) or with food will depend upon the specific drug as noted above. 

Some tablets combine sustained-release and rapid disintegration characteristics. Products such as K-Dur (Key Pharmaceuticals) combine coated potassium chloride crystals in a rapidly releasing tablet. In this particular instance, the crystals are coated with ethylcellulose, a water-insoluble polymer, and are then incorporated into a rapidly disintegrating microcrystalline cellulose (MCC) matrix. The purpose of this tablet is to minimize GI ulceration, commonly encountered by patients treated with potassium chloride. This simple but elegant formulation is an example of a solid dosage form strategy used to achieve clinical goals. 

Garlic supplements - powder tablets or capsules, steam-distilled oil, vegetable oil macerate extract, or extract aged in dilute alcohol - are widely available and are taken by millions. Since the active principle, allicin, is not present in garlic bulb, the supplements rely on the presence of precursor alliin and enzyme alliinase. In tests on 24 commercial brands of enteric-coated tablets, all except one gave low dissolution allicin release 83% of the brands released less than 15% of their potential allicin.78,79 Relevant factors were impaired enzyme activity caused by excipients and slow tablet disintegration. Caveat emptor ... 

The air temperature when Napoleon entered Russia was apparently as low as —35 °C, so the soldiers tin buttons converted from white to grey tin and, concurrently, disintegrated into powder. So, if this story is true, then Napoleon s troops froze to death because they lacked effective coat fastenings. Other common metals, such... 

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