Enteric-coated solid dosage forms containing sodium bicarbonate as a drug substance: an exception from the rule?

Area of Science:

• Pharmaceutical Sciences
• Drug Delivery Systems

Background:

• Sodium bicarbonate (sodium hydrogen carbonate) is an oral medication for metabolic acidosis and chronic kidney disease.
• Existing commercial products (bicaNorm, Nephrotrans) and novel pellet formulations require pharmaceutical quality assessment.

Purpose of the Study:

• To characterize and compare the in-vitro pharmaceutical quality and drug release profiles of different oral sodium bicarbonate formulations.
• To assess the biopharmaceutical suitability of soft capsules versus enteric-coated tablets and multiple-unit pellet formulations.

Main Methods:

• In-vitro disintegration and dissolution testing were performed on commercial and novel sodium bicarbonate formulations.
• Drug release was evaluated at various pH values, including acidic conditions representative of the stomach.

Main Results:

• Both marketed sodium bicarbonate products meet European Pharmacopoeia standards.
• Significant differences in drug release were observed at moderately elevated pH values.
• The soft capsule formulation (Nephrotrans) exhibited the lowest sodium bicarbonate release at pH 1 and 4.5.
• Early drug release from some formulations may lead to dose dumping and adverse effects due to carbon dioxide production.

Conclusions:

• Oral sodium bicarbonate dosage formulations represent an exception where monolithic soft capsules appear biopharmaceutically superior to enteric-coated tablets and pellet formulations.
• The findings align with patient reports of adverse effects associated with certain sodium bicarbonate products.