Tag Archives: stability

Stability Studies of Ampicillin Trihydrate in Suspensions and Acidic Aqueous Solutions

Rad I.1, Croitoru M. D.2, Pálffy Ágnes2, Gyéresi Á.3

1 “Dimitrie Cantemir” College, Tg. Mures
2 Public Health Centre, Tg. Mures
3 University of Medicine and Pharmacy of Tîrgu Mureș, Faculty of Pharmacy

Background: Ampicillin in trihydrate form is a b-lactamine antibiotic frequently used in therapy as suspensions and capsules. Because of the low stability only dry suspensions are sold, and also the low stability in acidic environment is source of unwanted side effects and bioavailability variations.
Aim: Our goal was to stabilize ampicillin so that a better stability can be obtained both in water suspensions and acidic solutions. This way misuse due to faulty preparation, side effects and bioavailability problems can be avoided.
Methods: In order to assess the changes in the ampicillin concentration high performance liquid chromatography (HPLC) and thin layer chromatography (TLC) methods have been used.
Results: None of the tried excipients improved stability of ampicillin suspensions. In contrast cyclodextrins and magnesium salts of glutamic and aspartic acid greatly improved the stability of ampicillin acidic solutions. In high amounts cyclodextrins also change the decomposition kinetic of ampicillin, which is usually a first order kinetic process.
Conclusions: Cyclodextrins and magnesium salts of glutamic and aspartic acid have the potential to be used in ampicillin containing formulations in order to increase its stability, bioavailability and to reduce adverse effects.

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Improvements of Amoxicillin Stability in Acidic Environment

Rad I.1, Croitoru M.D.2, Gyéresi Á.2

1 “Dimitrie Cantemir” College, Tg. Mures
2 Faculty of Pharmacy, University of Medicine and Pharmacy Tg. Mures

Background: Helicobacter pylori is a gram negative bacteria responsible for a series of gastrointestinal diseases: gastric and gastroduodenal ulcers. Usually used in combinations with other drugs, amoxicillin is effective against this germ. Amoxicillin has better stability than other penicillins in solutions with pH between 4 and 7, but stability is decreased at low pH values (gastric acidity).
Aim: Our goal was to improve amoxicillin’s stability by using auxiliary substances such b-cyclodextrin (b-CD), 2-hydroxypropil-bcyclodextrin (2-HP-b-CD), magnesium glutamate and magnesium aspartate.
Methods: Influence of these excipients on amoxicillin stability was assessed at pH value of 1.2 and also in weakly alkaline environment. High pressure liquid chromatography and thin layer chromatography were used to quantitate these influences.
Results: All the studied excipients improved the stability of amoxicillin, best results being recorded when amoxicillin was associated with cyclodextrins in a mole ratio of 1:5.
Conclusions: Poor stability of amoxicillin in acidic environments can be overcome by using cyclodextrins and magnesium salts of glutamic and aspartic acids.

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Improvements of Oxacillin Stability in a pH = 1.2 Acidic Environment

Rad I1, Croitoru MD2, Gyéresi Á2

1 Dimitrie Cantemir College, Tîrgu Mureș
2 University of Medicine and Pharmacy of Tîrgu Mureș, Faculty of Pharmacy

Introduction: Oxacillin sodium is a semisynthetic penicillin used in therapy against Staphylococcus species. It is orally administered as capsules. Because of the low stability of oxacillin in stomach acid, a low bioavailability is recorded during oral administration (30%).
The aim of this study was to improve, by using some auxiliary substances, the stability of oxacillin in acidic environment.
Methods: The improvement of oxacillin stability was measured by high performance liquid chromatography in the presence of β-cyclodextrin, 2-HP-β-cyclodextrin, magnesium glutamate and magnesium aspartate.
Results: Cyclodextrins significantly improved the stability of oxacillin in acidic environment. Glutamate and aspartate showed no effect on this regard. First order decomposition kinetics of oxacillin was modified by cyclodextrins.
Conclusions: Significant improvement of oxacillin stability and possible pharmacokinetics can be achieved by using cyclodextrins.

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Possibilities to Improve Benzylpenicillin and Phenoxymethylpenicillin Stability in Acidic Environment

Rad I1, Croitoru MD2, Gyéresi Á3

1 Dimitrie Cantemir College, Tîrgu Mureș, Romania
2 Department of Toxicology-Biopharmacy, Faculty of Pharmacy, University of Medicine and Pharmacy, Tîrgu Mureș, Romania
3 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Medicine and Pharmacy, Tîrgu Mureș, Romania

Background: Benzylpenicillin is water soluble natural penicillin used only by parenteral administration. Fast decomposition in acidic environment is the reason why benzylpenicillin can not be orally used. Phenoxymethylpenicillin is natural penicillin used in therapy by oral administration (filmed tablets, tablets, syrup, and suspension). It is relatively stable in acidic environment and has a bioavailability of about 50%.
Objective: The purpose of this study was to increase the stability of these penicillins in acidic environment (pH = 1.2) by using auxiliary substances: β-cyclodextrin, 2-hydroxypropil-β-cyclodextrin, magnesium glutamate and magnesium aspartate.
Methods: Improvements of stability were measured by high performance liquid chromatography in the absence and presence of the mentioned auxiliary substances.
Results: Cyclodextrins significantly improved the stability of the studied penicillins in acidic environment. Glutamate and aspartate showed no effect on this regard.
Conclusions: Significant improvement of benzylpenicillin and phenoxymethylpenicillin stability and possible pharmacokinetics can be achieved by using cyclodextrins.

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Morphological Changes of the Fetal Hip Joint and Their Effect on the Stability of the Joint During Its Intrauterine Development

Baróti Beáta1, Pánti Z2, Pap Zsuzsanna3, Dénes L3, Pávai Z3

1 Department of Radiology and Imaging, University of Medicine and Pharmacy, Tîrgu Mureş, Romania
2 Student, GM 5th year, University of Medicine and Pharmacy, Tîrgu Mureş, Romania
3 Department of Anatomy and Embryology, University of Medicine and Pharmacy, Tîrgu Mureş, Romania

Background: Hip joint dislocation and dysplasia are frequent congenital malformations with a multifactorial etiology with a major role played by intrauterine mechanical forces during development. Our aim was to define the surface of the femur and acetabulum, and to study the changes in geometrical parameters and the relationships between them during development.
Material and method: In this study we dissected the hip joints of 10 post-mortem fetuses. Fetal age was determined using crown-rump length (CRL) (min. 8.5 cm, max. 30 cm). Then we performed morphological and geometrical measurements on the articular components. We calculated the area of the articular surfaces, then determined the femoral head coverage and compared the antetorsion (AT) of the femur with the AT of the acetabulum.
Results: in the 3 months fetus the surface areas of the femur and acetabulum are almost identical, the femoral head coverage is maximal, and later with age progression the head coverage decreases, as its growth is more intense than that of the acetabulum. During development the increase of femoral AT determines the increase of the acetabular AT.
Conclusions: The decrease in femoral head coverage during development results in a decrease in articular stability. The femoral head’s position and compression plays an important role in the development of the acetabulum.

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