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STABILITY STUDY OF OMEPRAZOLE
CRISTINA IUGA*, MARIUS BOJIŢĂ
“Iuliu Haţieganu” University of Medicine and Pharmacy, Faculty of
Pharmacy, 400349, str. Louis Pasteur nr.6, Cluj Napoca, Romania
Department of Drugs Analysis
*corresponding author: iugac@umfcluj.ro
Abstract
We carried out a stability study of omeprazole in accordance with the stability testingof
pharmaceuticals guideline approved by the Romanian National Drug Agency [1].
Omeprazole is sensitive to heat, humidity, light, and organic solvents; consequently,
accelerated tests for stability evaluation were performed at 40ºC±2ºC and 75±5% relative humidity
(RH), according to the current official guideline. The samples were kept in a climatic chamber for
6 months in the conditionsdescribed above. Half of the samples were also exposed to light. The
samples were withdrawn from the climatic chamber and analyzed periodically (0; 0.2; 0.4; 2; 4; 5;
6 months) by an HPLC method with UV detection. A standard statistical methodology was used to
calculate the expiration date based on the analytical results obtained in the studied samples.
The purpose of this study was to use theresults obtained in accelerated stability testing
in order to estimate the expiration date in normal room temperature conditions (25ºC±2ºC).
Rezumat
Evaluarea stabilităţii omeprazolului şi estimarea perioadei sale de valabilitate a fost
realizată conform metodologiei de testare aprobată de Agenţia Naţională a Medicamentului
(ANM) [1].
Omeprazolul face parte din categoria substanţelor sensibilela temperatură, umiditate,
lumină şi solvenţi organici. Ca urmare, conform ghidului ANM, în acest caz evaluarea stabilităţii
s-a realizat în condiţii de testare accelerată la o temperatură de 40ºC±2ºC şi o umiditate relativă
(UR) de 75±5%. Probele au fost păstrate timp de 6 luni într-o cameră climatică în condiţiile
descrise mai sus; jumătate dintre probe au fost expuse şi la lumină. Periodic(7, 14, 64, 128, 150,
180 zile) au fost prelevate probe care au fost analizate printr-o metodă HPLC cu detecţie UV.
Rezultatele obţinute au fost prelucrate matematic şi statistic în vederea stabilirii perioadei de
valabilitate a omeprazolului.
Scopul acestui studiu a fost acela de a utiliza rezultatele obţinute la testarea accelerată
pentru estimarea perioadei de valabilitate a omeprazoluluiîn condiţii normale de temperatură
(25ºC±2ºC).
Keywords: omeprazole, stability, humidity, light.

Introduction
Omeprazole (OPZ), 5-methoxy-2-[[(4-methoxy-3,5-dimethyl-2pyridinyl) m ethyl]sulphinyl] - 1H - benzimidazole is a substituted
benzimidazole compound and prototype anti-secretory agent. OPZ is the
first “proton pump inhibitor” widely used in the prophylaxis and treatment
ofgastroduodenal ulcers and the treatment of symptomatic gastro-

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esophageal reflux. It interacts with H+/K+ ATPase in the secretory
membranes of the parietal cells and it is very effective in the treatment of
the Zollinger–Ellison syndrome.
OPZ is a lipophilic, weak base with pKa1= 4.2 and pKa2= 9 that may
be degraded unless protected against acid conditions. Itcontains a
tricoordinated sulphur atom in a pyramidal structure and therefore can exist
in two different optically active forms, (S)- and (R)-omeprazole.
The number of decomposed products of omeprazole in different
conditions has been identified and characterized by Brändström et al [2]. D.
Castro and al. described derivative spectrophotometry and HPLC methods
[3].
The HPLC method is theofficial one proposed by the United States
Pharmacopeia (USP 25) for the determination of omeprazole and for its
quantification from bulk material. This procedure can be used in stability
studies as there is no interference between the drug and its decomposition
products.
In order to shorten the development period of a pharmaceutical
formulation, the chemical stability of pharmaceuticals was...