Product Information

Registration Status: Active

PROMESEC GASTRO-RESISTANT CAPSULE 20MG is approved to be sold in Singapore with effective from 2018-08-14. It is marketed by DUOPHARMA (SINGAPORE) PTE LTD, with the registration number of SIN15522P.

This product contains Omeprazole 20mg in the form of CAPSULE, ENTERIC COATED. It is approved for ORAL use.

This product is manufactured by Hetero Labs in INDIA.

It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.



A highly effective inhibitor of gastric acid secretion used in the therapy of stomach ulcers and Zollinger-Ellison syndrome. Omeprazole belongs to a class of antisecretory compounds, the substituted benzimidazoles, that suppress gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell.


Omeprazole is indicated for the treatment of duodenal ulcers, benign gastric ulcers, gastroesophageal reflux disease (GERD), heartburn and other symptoms associated with GERD, erosive esophagitis, and long-term treatment of pathological hypersecretory conditions like Zollinger-Ellison syndrome, multiple endocrine adenomas, and systemic mastocytosis.

Mechanism of Action

Omeprazole is a proton pump inhibitor that suppresses gastric acid secretion by specific inhibition of the H+/K+-ATPase in the gastric parietal cell. By acting specifically on the proton pump, omeprazole blocks the final step in acid production, thus reducing gastric acidity.


The delayed-release capsule are enteric-coated (as omeprazole is acid-labile) so the absorption of omprazole begins once the granules leave the stomach. Absorption is rapid. Peak plasma levels occur within 0.5 - 3.5 hours. The absolute bioavailability (compared with intravenous administration) of the delayed-release capsule is 30-40% at doses of 20 - 40 mg, due to presystemic metabolism. This value increases slightly when given repeatedly. Based on a relative bioavailability study, the AUC and Cmax of PRILOSEC (omeprazole magnesium) for Delayed-Release Oral Suspension were 87% and 88% of those for PRILOSEC Delayed-Release Capsules, respectively. Interestingly, when the 40 mg delayed release capsule is given with or without applesauce, it is bioequivalent. However, when the 20 mg delayed release capsule is given with the same conditions, it is not bioequivalent. When the same capsule is given to the elderly, bioavailability increases. Omeprazole was 76% bioavailable.
Hepatic. Omeprazole is extensively metabolized by the cytochrome P450 (CYP) enzyme system. The two primary CYP isozymes involved are CYP2C19 and CYP3A4. Metabolism is stereoselective in which the S-isomer is converted to 5'O-desmethylomeprazole via CYP2C19. CYP3A4 converts the S-isomer to 3-hydroxyomeprazole. The R-isomer is converted to 5-hydroxyomeprazole by CYP2C19. CYP3A4 converts the R-isomer to any four different metabolites: 5-hydroxyomeprazole (5-OH OME), omeprazole sulfone (OME sulfone), 5'-O-desmethylomeprazole (5'-desmethyl OME), and 3-hydroxyomeprazole (3-OH OME).


* 500 - 600 mL/min [Total body clearance, healthy subjects, delayed-release capsule] * 250 mL/min [Plasma clearance, Geriatric] * 70 mL/min [Plasma clearance, Hepatic Impairment]


Symptoms of overdose include confusion, drowsiness, blurred vision, tachycardia, nausea, diaphoresis, flushing, headache, and dry mouth.

Active Ingredient/Synonyms

OMEP | Omeprazol | Omeprazolum | Omeprazole |

Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.


  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank