Development and evaluation of an omeprazole-based delayed-release liquid oral dosage form

Modified-release oral dosage forms are commonly used in pharmaceutics to delay or sustain the release of drugs. Nowadays, they are only marketed as solid dosage forms such as capsules or tablets. Therefore, the development of a liquid oral dosage form with modified-release properties has been keenly awaited to increase the compliance of patients with a swallowing impairment, such as paediatric, older or critically ill patients. In this study, a new technology has been developed that consists of multi-layered particles suspended extemporaneously in a syrup, using omeprazole as a model drug. The coating procedure was optimized to obtain a yield of minimum 90% w/w and a mean diameter below 500 µm. Eudragit® E100 and Eudragit® L100-55 were used to prevent the early release of omeprazole in the syrup and in the acidic environment of the stomach, respectively. These polymers allowed the stability of the coated particles to be ensured when dispersed in a liquid and the enteric release of the drug to be targeted. It was demonstrated that our new system presented similar release performances to existing marketed enteric dosage forms. It is able to protect omeprazole for 2 h in acidic medium at pH 1.2, while omeprazole was entirely released at pH 6.8 within 45 min. Once the final suspension is prepared extemporaneously, it presents sufficient stability to guarantee the administration of multiple doses filled into a syrup bottle and kept for a limited storage time at room temperature (e.g. up to 10 doses to be administered within 10 days).