Drug Product Testing, Methods and Stability Studies


Depending on the specific drug product, testing at Dow Development Laboratories may include:

  • quantitative assay of API and preservative
  • pH
  • viscosity
  • appearance
  • water content
  • light microscopy
  • conductivity
  • osmolality
  • package integrity
  • in vitro release testing (IVRT)

DDL has extensive experience in testing a wide variety of topical products containing new chemical entities (NCEs) as well as approved drugs, combination products, oligonucleotides, peptides, proteins, hygroscopic molecules and light-sensitive molecules.


Analytical methods are developed and then validated in a stage-appropriate manner as the product moves from R&D to  Good Laboratory Practices (GLP) and through Phase I and II clinical studies, with strict oversight by the quality assurance group.


Stability studies may be conducted in R&D chambers (25oC and 40oC) or in temperature- and humidity-controlled Good Manufacturing Practices (GMP) chambers at International Conference for Harmonization (ICH) conditions (5oC, 25oC/60% RH, 30oC/65% RH and 40oC/75% RH). Chambers maintained at -20oC are also available on-site.

Experience Specific to Topical Products

Our analytical team is well-versed in overcoming the unique challenges in method development and testing that topical products can present. This includes:

  • resolution of active pharmaceutical ingredient (API) and preservative from the multiple excipients in a topical product
  • efficient extraction of the API from the formulation (ointments, gels, creams and suspensions)
  • techniques for improving sensitivity for drug products at low strengths
  • combination products


Analytical testing equipment at DDL includes:

  • HPLC and uHPLC, with refrigerated auto-samplers and Diode Array Detectors
  • Triple Quadrupole LC/MS
  • Thermo Trace 1310 GC
  • ELSD
  • Franz cell manifolds (IVRT)
  • Spectrophotometers, UV/Vis
  • Viscometers (Brookfield), osmometers, pH meters
  • Coulometric titrators for Karl Fisher analysis

For questions or inquiries as to how Dow Development Laboratories can help you with your topical product development needs, please contact us at khanley@dowdevelopmentlabs.com.