Royal College of Surgeons in Ireland
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Investigation of the physical, chemical and microbiological stability of losartan potassium 5 mg/mL extemporaneous oral liquid suspension

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journal contribution
posted on 2021-08-03, 13:15 authored by Lisa Foley, Jennifer Toney, James BarlowJames Barlow, Maura O’Connor, Deirdre Fitzgerald HughesDeirdre Fitzgerald Hughes, Zeibun Ramtoola
Extemporaneous oral liquid preparations are commonly used when there is no commercially available dosage form for adjustable dosing. In most cases, there is a lack of stability data to allow for an accurately assigned shelf life and storage conditions to give greater confidence of product safety and efficacy over its shelf life. The aim of this study was to evaluate the physical, chemical and microbiological stability of an extemporaneous oral liquid suspension of losartan potassium, 5 mg/mL, used to treat paediatric hypertension in Our Lady's Children's Hospital Crumlin, Ireland. The losartan content of extemporaneous oral suspensions, prepared with and without addition of water, was measured by UV and confirmed by HPLC analysis. Suspensions were stored at 4 °C and room temperature (RT) and were monitored for changes in; pH, colour, odour, re-dispersibility, Total Aerobic Microbial Count, Total Yeast and Mould Count and absence of E. coli. Results showed that suspensions prepared by both methods, stored at 4 °C and RT, were physically and microbiologically stable over 28 days. Initial losartan content of all suspensions was lower than expected at 80-81% and did not change significantly over the 28 days. HPLC and NMR did not detect degradation of losartan in the samples. Suspensions prepared in water showed 100% losartan content. The reduced initial losartan content was confirmed by HPLC and was related to the acidic pH of the suspension vehicle. Physiochemical properties of the drug are important factors for consideration in the selection of suspension vehicle for extemporaneous compounding of oral suspensions as they can influence the quality, homogeneity and efficacy of these preparations.


Health Research Board (HRB) Ireland (SS-2015-1531).



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Published Citation

Foley L, Toney J, Barlow JW, O'Connor M, Fitzgerald-Hughes D, Ramtoola Z. Investigation of the physical, chemical and microbiological stability of losartan potassium 5 mg/mL extemporaneous oral liquid suspension. Molecules. 2021;26(2):301.

Publication Date

8 January 2021

PubMed ID



  • School of Pharmacy and Biomolecular Sciences
  • Chemistry
  • Beaumont Hospital
  • Clinical Microbiology
  • Undergraduate Research

Research Area

  • Vascular Biology
  • Health Professions Education
  • Chemistry and Pharmaceutical Sciences
  • Immunity, Infection and Inflammation
  • Biomaterials and Regenerative Medicine


MDPI AG (Multidisciplinary Digital Publishing Institute)


  • Published Version (Version of Record)