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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."
INCORRECT USE OF EQUIPMENT
| Error Type |
Description |
Avoiding the Error |
|---|
| Incorrect use of equipment |
This results in preparations that are of less-than-desired quality and aesthetics, including improper mixture, insufficient particle size reduction, separation of phases, discoloration, precipitation, and so on. Electrostatic charges that may be present during weighing are problematic |
Confirm that each compounding pharmacist knows how to correctly use each piece of equipment involved in the formulation, including not only actual operation, but also actual maintenance and, in some cases, simple repair or replacement of disposable items. A number of techniques are available to minimize electrostatic charges, and devices can be purchased from suppliers to accomplish this. |
| Stirring rod in graduated cylinder while measuring |
Improper volume of the required vehicle can result in a higher-than-desired concentration of the API. |
Remove the stirring rod during final measuring of the volume of vehicle to be added to the compounded preparation. |
| Magnetic stir bar in measuring device while measuring |
When using a calibrated beaker and so on, leaving a magnetic stir bar in the beaker will result in an improper volume of the vehicle and, in turn, a higher-than-desired concentration of the API; less vehicle will be present. |
Remove the magnetic stir bar from the beaker or container when adding the vehicle to the calibrated volume line of the container. |
| pH meter not calibrated before use |
An improper pH reading can result in a decrease in the stability of the drug as well as a decrease in the solubility of the drug, resulting in precipitation and so on. |
Always calibrate the pH meter before using it each day and several times throughout the day. Clean or rinse the electrodes between each measurement. |
| Electronic balance not calibrated daily |
Improper weighings result in too little or too much of an ingredient in the final compounded preparation. |
Calibrate each balance at the beginning of each work shift and throughout the shift as required. |
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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