Topical preparations often contain preservatives to retard growth of micro-organisms that might cause deterioration of the product or which might cause disease in the patient.
Features of the ideal preservative:
(1) effective at a relatively low concentration against a broad spectrum of micro-organisms that could cause disease or result in deterioration of the product
(2) soluble in the required concentration (not precipitated)
(3) nontoxic at the in-use concentration
(4) nonsensitizing at the in-use concentration
(5) compatible with the ingredients of the formulation and package components
(6) free from objectionable odors and colors
(7) stable over a wide spectrum of conditions (heat, cold, time, handling)
(8) inexpensive
For the implementation I used a 4-point Likert scale for each feature.
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