ANSWER:

Omeprazole needs to be given into an alkaline medium for a variety of reasons:
 

• the drug is acid labile and will be broken down in an acidic environment
• the drug is better absorbed into the parietal cell when in an alkaline environment
• the tablet coating will only dissolve in an alkaline environment, thus if not broken down before hand may cause significant clogging of an NG or feeding tube.

To prevent clogging of the tube:
Allow the crushed omeprazole tablet to completely dissolve in 10 mL of sodium bicarbonate solution (for a minimum of 10 minutes) prior to administration.  Use a preloaded syringe or 50 ml vial of sodium bicarbonate for injection.  Keep the remaining ampule or vial for subsequent doses.

To prevent breakdown in the stomach:
For the initial dose only, the stomach should be alkalinized prior to administration.  Administer 50 ml of sodium bicarbonate before administering the omeprazole.  Following administration of the drug, give 50 additional ml of sodium bicarbonate.

A bicarbonate flush is not required for subsequent doses as the omeprazole should maintain an alkaline stomach pH.  The tube should be flushed before and after drug administration to maintain patency (large volumes are required to prevent tube clogging when omeprazole is administered).

Administration through a jejunal or duodenal feeding tube:
Because the pancreas secretes bicarbonate into the small bowel, omeprazole can be administered directly into small bowel feeding tubes without the addition of sodium bicarbonate.  The tube should be flushed with 50 ml of water after administration to maintain tube patency.

References:

Astra Pharmaceuticals, direct information
LHSC Internal Hospital Recommendations