Reduced Tetracycline Bioavailability Caused by Magnesium Aluminum Silicate in Liquid Formulations of Bismuth Subsalicylate

Abstract

In vitro and in vivo data from this study indicate that Veegum, a suspending agent, and not the active agent bismuth subsalicylate, is the primary ingredient in liquid formulations of bismuth subsalicylate responsible for a decrease in tetracycline bioavailability. In addition, the mechanism of interaction is not likely due to complexation between tetracycline and bismuth subsalicylate, as previously postulated, but rather is caused by adsorption of tetracycline to the excipient Veegum, which is present only in the liquid formulation of bismuth subsalicylate. The clinical relevance of this interaction has not been determined.

A Triple and Quadruple Therapy with Doxycycline and Bismuth for First‐Line Treatment of Helicobacter pylori Infection: A Pilot Study

“…While esomeprazole, amoxicillin, and DOX were administered before breakfast and supper, bismuth salt was administered 3 hours later as it may bind with DOX and prevent its full absorption .…”

Rifabutin Containing Triple Therapy and Rifabutin with Bismuth Containing Quadruple Therapy for Third‐Line Treatment of Helicobacter pylori Infection: Two Pilot Studies

“…Bismuth salts were administered at 11.00 AM and 11.00 PM, that is three hours after amoxicillin and rifabutin, since they may bind with the antibiotics, a process that may reduce their full absorption [37,38].…”

Precipitation Behavior of Highly Soluble Amphiphilic Drugs in Solution

“…3 Drug-excipient interaction in solution can also compromise oral drug absorption, as is the well-known case with tetracycline antibiotics with counterions such as magnesium aluminum silicate. 4 The building and strengthening of the drug-excipient species has been shown before, especially in the case of protein therapeutics, 5 with their molecular basis being electrostatic and cation−pi interactions, preferential hydration, dispersive forces, and hydrogen bonding.…”