Does bicarbonate protect omeprazole when co-administered?

Tuleu, C., Wang, Y-W. and Taylor, K.M.G. (2008) Does bicarbonate protect omeprazole when co-administered? In: NPPG 14th Annual Conference, 14-16 November 2008, Birmingham, UK.

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Background Liquid formulations can be prepared from solid dosage forms, using various vehicles, for administration orally or by NGT. Sodium bicarbonate (NaHCO3) is often recommended for preparation of oral dispersions of omeprazole from MUPS or enteric-coated capsules. It is claimed that e/c pellets or granules, crushed or intact, should only be used in alkaline bicarbonate solution to protect acid-labile omeprazole from low pH gastric juice. However, in practice, various NaHCO3strengths are used without proof of their efficacy in ensuring omeprazole stability. Objectives To investigate, in vitro, the neutralizing capacity of NaHCO3 and the neutralizing ability of extemporaneously prepared 2 mg/ml omeprazole suspensions, at a range of pH and volumes clinically relevant to the paediatric population. Methods Titration of hydrochloric acid (HCl) and BP Simulated Gastric Fluid (SGF) at pH 1 to 5 by NaHCO3 0, 1.26, 4.2 and 8.4% was undertaken. Equivalence points were determined to compare neutralising capacity of the solutions. 2mg/ml omeprazole suspensions were prepared from MUPS in the aforementioned NaHCO3 solutions. To assess their neutralising ability, the ratio Stomach Volume (SGF):Omeprazole Suspension Dose Volume (BNFc) was estimated for 7.7 kg (6 months), 18 kg (5 years), 39 kg (12 years) and 60 kg young adult. The suspension volume was kept constant and pH values were measured in triplicate while SGF (pH 1 to 4) was added to mimic the whole range of in vivo situations Results HCl and SGF results were similar and showed that for pH 1, 8.4% bicarbonate solution was superior to 4.2 and 1.26%. For pH 2, 8.4% and 4.2% were equivalent and above that pH, 1.26% was also as effective. Water had no neutralizing capacity. The average gastric volumes were estimated from 25 publications at 0.15 ml/kg for a 6month baby, 0.30 ml/kg for a 5 year old and 0.40ml/kg for a 12 year old child. Ratios Stomach Volume: Suspension Dose Volume ranged from 1:0.83 (older) to 1:3.5 (younger children). At pH 1, when a ratio of 1:0.83 was investigated, 1.26% NaHCO3 did not maintain the pH above 5.5 (=dissolution pH of enteric coating). For pH 2 to 4, whatever was the ratio and NaHCO3concentration (except water), the pH remained above 5.5. Visual degradation of intact MUPS omeprazole (purple colour, ref 1) was observed after 90 minutes in water. Conclusion The ability of NaHCO3 solutions to neutralize acidic artificial pH (HCl or SGF) decreased with decreasing concentration of bicarbonate. As there were few differences in neutralizing ability of 2mg/ml omeprazole extemporaneous suspensions in simulated in vivo conditions, 4.2% NaHCO3 vehicle could be an alternative to widely used 8.4% solutions to reduce sodium intake. However 1.26% sodium bicarbonate solution should not be used in children greater than 50 kg. Water is not recommended.

Item Type:Conference or Workshop Item (Poster)
Departments, units and centres:Department of Pharmaceutics > Department of Pharmaceutics
ID Code:1229
Deposited By:Library Staff
Deposited On:24 Jun 2009 15:25
Last Modified:14 Oct 2011 09:55


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