Review of Changes in Topical Drug Product Classification - Pharmaceutical Technology

Latest Issue
PharmTech

Latest Issue
PharmTech Europe

Review of Changes in Topical Drug Product Classification
This article summarizes the classification systems for topical liquid and semisolid dosage forms used for dermatological application and notes some differences between FDA and USP classification.


Pharmaceutical Technology
Volume 32, Issue 10, pp. 66-74

Is the semisolid a paste, gel, ointment, or cream?

A paste is defined as "a semisolid dosage form, containing a large proportion (20–50%) of solids finely dispersed in a fatty vehicle. This dosage form is generally for external application to the skin or mucous membranes." For the decision tree, one must as the question, Does the semisolid contain >50% water and volatiles? If the answer is no, then one should ask, Does the semisolid contain a large proportion (20–50%) of dispersed solids? If the answer is yes, then the dosage form is classified as a paste. This "new" definition of a paste is much more detailed than the pre-2006 definition, which states that a paste is a semisolid dosage form that contains one or more drug substances intended for topical application. "Water and volatiles" percentage for all of the semisolid dosage forms is determined by loss on drying when heated at 105 C until constant weight is achieved. Dispersed solids is not defined, but is presumably estimated from knowledge of the components and composition of the formulation.

A gel is defined as "a semisolid dosage form that contains a gelling agent to provide stiffness to a solution or a colloidal dispersion. A gel may contain suspended particles." This definition is footnoted with "A colloidal dispersion is a system in which particles of colloidal dimension (typically between 1 nm and 1 μm) are distributed uniformly throughout a liquid." For the decision tree, one must first ask the question, Does the semisolid contain >50% water and volatiles? If the answer is yes, then one must ask, Is the semisolid a solution or colloidal dispersion stiffened with a gelling agent? If the answer is yes, then the dosage form is classified as a gel.

Ointment is defined as "a semisolid dosage form, usually containing <20% water and volatiles and >50% hydrocarbons, waxes, or polyols as the vehicle. This dosage form is generally for external application to the skin or mucous membranes." For the decision tree, one should first ask, Does the semisolid contain >50% water and volatiles? If the answer is no, then one should ask, Does the semisolid contain a large proportion (20–50%) of dispersed solids? If the answer is no, then one should ask, Does the semisolid contain >50% of hydrocarbons, waxes, or polyols such as polyethylene glycol and <20% water and volatiles? If the answer is yes to both parts of the question, then the dosage form is classified as an ointment.

With this classification system, cream becomes the default dosage form. If one or both of the two criteria for ointment are not meet, then the product is a categorized as acream. Likewise if the criteria "containing >50% water and volatiles required for a gel" is met, but the semisolid is an emulsion, then the product is a cream. Cream is defined as "an emulsion, semisolid dosage form, usually containing >20% water and volatiles and/or <50% hydrocarbons, waxes, or polyols as the vehicle. This dosage form is generally for external application to the skin or mucous membranes."


ADVERTISEMENT

blog comments powered by Disqus
LCGC E-mail Newsletters

Subscribe: Click to learn more about the newsletter
| Weekly
| Monthly
|Monthly
| Weekly

Survey
FDASIA was signed into law two years ago. Where has the most progress been made in implementation?
Reducing drug shortages
Breakthrough designations
Protecting the supply chain
Expedited reviews of drug submissions
More stakeholder involvement
Reducing drug shortages
27%
Breakthrough designations
9%
Protecting the supply chain
41%
Expedited reviews of drug submissions
9%
More stakeholder involvement
14%
View Results
Jim Miller Outsourcing Outlook Jim Miller Health Systems Raise the Bar on Reimbursing New Drugs
Cynthia Challener, PhD Ingredients Insider Cynthia ChallenerThe Mainstreaming of Continuous Flow API Synthesis
Jill Wechsler Regulatory Watch Jill Wechsler Industry Seeks Clearer Standards for Track and Trace
Siegfried Schmitt Ask the Expert Siegfried SchmittData Integrity
Sandoz Wins Biosimilar Filing Race
NIH Translational Research Partnership Yields Promising Therapy
Clusters set to benefit from improved funding climate but IP rights are even more critical
Supplier Audit Program Marks Progress
FDA, Drug Companies Struggle with Compassionate Use Requests
Source: Pharmaceutical Technology,
Click here