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Classification, Description, and Prevention of Errors
Compounding errors can be divided into the following categories:
- General Errors,
- Incorrect Ingredients,
- Incorrect Concentration,
- Incorrect Use of Equipment,
- Physicochemical Issues,
- Microbiological Contamination,
- Analytical Testing Issues,
- Microbiological Testing Issues, and
- Miscellaneous Errors.
We will continue to look at errors using the format or subject-headings of "Error Type," "Description," and "Avoiding the Error."
PHYSICOCHEMICAL ISSUES
| Error Type |
Description |
Avoiding the Error |
|---|
| Nonhomogeneous mixing |
Large standard deviations in powdered dosage forms (capsules, creams, gels, ointments, papers, etc.) can occur because of mixing that does not result in a homogeneous blend of the API in the bulk of the prescription. |
Confirm the mixing procedures that are used in compounding for different types of preparations. Uniform use of equipment, mixing times, powder particle size, and so on are critical for homogeneous mixing. Dissolve salts in a minimum quantity of water before adding to a semisolid vehicle to prevent grittiness. Stir constantly when combining two liquids to prevent a layering effect and a potential incompatibility. The particle size may be too large and require comminution or levigation. |
| Solubility issues and precipitation |
These issues result in too little API in some liquid doses and then excessive API in doses at other times. |
Be aware that solvent, pH, cosolvents, temperature, and other factors can alter the solubility or precipitation of APIs in compounded preparations. Control these variables properly to prevent precipitation, haze formation, and so on. |
| Failure to follow instructions |
This failure can even involve official labeling; in the reconstitution of manufactured antibiotics, failure to use the correct volume of water will result in an incorrect concentration of the API. An example was reported where the powder was not reconstituted and the patient measured and took the powder. This error also applies to the lack of following precise instructions on the formulation record. |
Follow steps exactly in the official labeling and the formulation record to compound a correct prescription. |
Loyd V. Allen, Jr., PhD, RPh
Editor-in-Chief
International Journal of Pharmaceutical Compounding
Remington: The Science and Practice of Pharmacy Twenty-second edition
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