riopan and aluminum-hydroxide--magnesium-hydroxide--drug-combination

Norfloxacin is a fluorquinolone that can interfere with certain antacids (derivatives of Al and Mg) because its dissolution profiles are dependent on pH. Furthermore, it can form insoluble complexes that modify its absorption and bioavailability. Two sensitive and selective analytical methods using fluorescence (FL) and UV spectrophotometry (UV) have been developed to study the dissolution behaviour in gastric juice of different formulations of norfloxacin in tablets. There are no significant differences when the samples are measured by both methods and their ruggedness in the presence of some excipients is proven. From this, it is concluded that they are effective for this study. When different antacids are added to the dissolution medium, using UV and FL methods with the same samples, totally different dissolution profiles appear. Using FL, it would appear that up to 400% of the amount of norfloxacin in the tablet is released. These profiles are misleading because the uniformity of dosage units was tested before the dissolution studies. It is proven that the antacids dissolved in gastric juice do not produce fluorescence, but cause important analytical interferences with norfloxacin. This may be because their association with Al3+ or Mg2+ forms a new compound. Nevertheless, it is observed that this effect is more important in some antacids (Almagate, Magaldrate). This may be because their ability to deliver Al to the medium is greater.

Topics: Aluminum Hydroxide; Antacids; Anti-Infective Agents; Carbonates; Drug Combinations; Hydrogen-Ion Concentration; Magnesium Hydroxide; Norfloxacin; Solubility; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tablets

The rate of gastric emptying of two antacids, magaldrate and Maalox, was investigated using scintigraphy. Successful labelling of the antacids was carried out with 99mTc. The stability of the 99mTc-labelled antacids was satisfactory and there was no difference in antacid capacity between the labelled and unlabelled antacids. The studies were carried out on 15 healthy male volunteers. After an eight hour fast each subject ingested a standardised meal of 95.7 MJ (400 kcal). One hour later 10 ml of one of the two antacids previously labelled with 99mTc was administered. Serial detection by anterior and posterior projection of the amount of antacid retained in the stomach was performed to determine gastric emptying of antacid. One week later the study was repeated under the same conditions with the other antacid also labelled with 99mTc. The mean (SD) percentages of antacid retained in the stomach fit a linear model with a t1/2 of 86.6 (15.3) minutes for magaldrate and 52.3 (5.2) minutes for Maalox (p less than 0.01). When the mean percentages of retention at six time intervals were compared for both antacids, it was found that Maalox emptied much faster (p less than 0.01 at 15 and 30 minutes, p less than 0.02 at 45, 60, 75, and 90 minutes).

Topics: Adult; Aluminum Hydroxide; Antacids; Diphosphates; Drug Combinations; Gastric Emptying; Humans; Magnesium Hydroxide; Male; Reference Values; Technetium; Technetium Tc 99m Pyrophosphate