Accounting for the effects of moderately increased pressure on the energetics of melting and solubility in metered dose inhalers

Erik Mogalian, Kia Sepassi, Paul Brian Myrdal

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

The purpose of this study is to account for thermodynamic variations due to changes in the physical environment of propellant-based systems, particularly metered dose inhalers (MDIs). Twenty organic compounds were measured via differential scanning calorimetry under ambient pressure, 60 psi, and 90 psi. The increase in pressure did not affect the melting point of any of the compounds. A modest increase (∼8%) in enthalpy of fusion was noted. This correlates to a modest increase in entropy of fusion, and thus ideal crystalline solubility, though the magnitude of this change depends primarily on the melting point of the given compound. Because the relationship between melting point and solubility is logarithmic, compounds with higher melting points are affected more by this increased energy of melting. Based on the findings, modest changes can be made to predictive models to estimate solubility in propellant systems to account for changes in the physical environment of MDIs.

Original languageEnglish (US)
Pages (from-to)930-935
Number of pages6
JournalDrug Development and Industrial Pharmacy
Volume34
Issue number9
DOIs
StatePublished - Sep 1 2008

Keywords

  • 134a
  • Hydrofluoroalkane
  • Metered dose inhaler
  • Pressure
  • Propellant
  • Solubility

ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science
  • Drug Discovery
  • Organic Chemistry

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