Review of Changes in Topical Drug Product Classification - Pharmaceutical Technology

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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

Augmented, metered, and other modifiers

The CDER Data Standards Manual lists additional dosage form modifiers. Augmented ointments, lotions, and creams are listed. Each definition for an augmented dosage form carries the note: "CDER has decided to refrain from expanding the use of this dosage form due to difficulties in setting specific criteria that must be met to be considered 'augmented.'" Thus, use of the term augmented to describe a dosage form that enhances drug delivery does not appear to be a classification option for products currently in development.

Metered is an approved modifier for aerosol, spray, and gel. Gel, metered is defined as "a gel preparation, with metered dose valves, which allow for the delivery of a uniform quantity of gel upon each activation." Likewise, aerosol, metered is defined as "a pressurized dosage form consisting of metered dose valves which allow for the delivery of a uniform quantity of spray upon each activation," and spray, metered is defined as "a nonpressurized dosage form consisting of valves which allow the dispensing of a specified quantity of spray upon each activation."

Other modifiers appear in the CDER Data Standards Manual. Aerosol is modified by foam, powder, and spray. Patch is modified by extended release and extended release, electrically controlled. Shampoo is modified by suspension, and lotion is modified by shampoo. Spray is also modified by suspension. Although there are various orders for the modifiers, USP states that any dosage form for any drug substance can be unambiguously identified by a combination of taxonomic terms from each tier, taking the form: [drug substance][route of administration][physical state][release pattern].

Conclusion

Topical drug product classification with regard to the most common dosage forms advanced dramatically on June 21, 2006 when the CDER Data Standards Manual adopted recommendations from the Buhse et al. This resolved many of the ambiguities that contributed to confusion not only in CDER databases but also the NDC Directory and FDA Orange Book. Although these advances are appreciated within industry, additional modifications can further improve the classification system for topical drug products. Redundant or obsolete definitions such as tincture and liniment should carry notes that more-specific terms such as lotion or solution should be used when appropriate. Common dosage forms such as aerosols, sprays, and shampoos should become part of the Bushe decision tree on topical dosage form nomenclature. Commonly used dosage forms such as pledgets should be added to the CDER Data Standards Manual. The USP PDF Expert Committee suggestion to make the term lotion obsolete should be reconciled with the classification system used by FDA. Finally, the boundary between a liquid of pseudoplastic flow and a semisolid not flowing at low shear stress leaves considerable latitude for classifying an emulsion as either a cream or lotion. It is important to agree that while some formulations are clearly creams and others are clearly lotions, classification of formulations in the middle requires rheological characterization such as shear rate versus shear stress plots and not simply seeing whether the product pours.

David W. Osborne, PhD, is vice-president of product development at Dow Pharmaceutical Sciences, 1330 Redwood Way, Petaluma, CA,

Submitted: Jan. 3, 2008. Accepted: Apr. 11, 2008.

References

1. J.P. Remington, The Practice of Pharmacy (J.B. Lippincott Company, Philadelphia, PA, 5th ed. 1907), pp. 1256-1278.

2. USP 30–NF 25 (The United States Pharmacopeial Convention Rockville, MD, 2006), p. 624.

3. Physicians' Desk Reference (Thomson PDR, Montvale, NJ, 60th ed., 2006), p. 3020.

4. L. Buhse et al., "Topical Drug Classification," Int. J. Pharma. 295, 101–112 (2005).

5. K. Marshall et al., "Development of a Compendial Taxonomy and Glossary for Pharmaceutical Dosage Forms," Pharm. Forum 29 (5), 1742–1752 (2003).

6. CDER Data Standards Manual (Rockville, MD), http:// http://www.fda.gov/cder/dsm/DRG/drg00201.htm, accessed Sept. 8, 2008.

7. Code of Federal Regulations, Title 21 Food and Drugs, Section 314.101(d)9 .

8. "USP Topical Dosage Forms Nomenclature," available at http:// http://www.fda.gov/OHRMS/DOCKETS/ac/03/slides/3926S1_13_Carlin_files/frame.htm accessed Sept. 8, 2008.

9. Physicians' Desk Reference (Thomson PDR, Montvale, NJ, 60th ed., 2006), p. 3330.

10. Physicians' Desk Reference (Thomson PDR, Montvale, NJ, 60th ed., 2006), p. 640.

11. Physicians' Desk Reference (Thomson PDR, Montvale, NJ, 60th ed., 2006), pp. 1107–1108.

12. M. Naser, "Pharmaceutical Nomenclature: Issues and Challenges,"presented at Advisory Committee for Pharmaceutical Sciences, Oct. 22, 2003, available at http:// http://www.fda.gov/ohrms/dockets/ac/06/briefing/2006-4241B1-02-29-FDA-Topical%20DF%20October%202003%20Adv%20edited.pdf, accessed Sept. 8, 2008.


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