Physicochemical Properties of Drugs

Physicochemical properties are all the physical and chemical properties of a drug, which are influence the drug performance or action.

Various Physico-Chemical Properties of Drugs

Thermodynamic properties

  • Melting and sublimation temperatures
  • Internal energy (i.e. structural energy)
  • Enthalpy (i.e. heat content)
  • Heat capacity
  • Entropy
  • Free energy and chemical potential
  • Thermodynamic activity
  • Vapour pressure
  • Solubility

Kinetic properties

  • Dissolution rate
  • Rates of solid state reactions
  • Stability

Spectroscopic properties

  • Electronic transitions (i.e. ultraviolet visible absorption spectra)
  • Vibrational transitions (i.e. infrared absorption spectra and Raman spectra)
  • Rotational transitions (i.e. far infrared or microwave absorption spectra)
  • Nuclear spin transitions (i.e. nuclear magnetic resonance spectra)

Surface properties

  • Surface free energy
  • Interfacial tensions
  • Habit (i.e. shape)

Mechanical properties

  • Hardness
  • Tensile strength
  • Compressibility
  • Handling flow and blending

Packing properties

  • Molar volume and density
  • Refractive index
  • Conductivity electrical and thermal
  • Hygroscopicity

If a deficiency is detected, then the project team should decide on the molecular modification(s) that would most likely improve the drug’s properties. Salts, prodrugs, solvates, polymorphs, or even new analogs may emerge from this modification effort.

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