We thank Chollet and colleagues for their comments regarding our article, and agree with them that compounding of 17-hydroxyprogesterone caproate (17-OHPC) or any other preparation in the absence of appropriate quality control may pose a risk to patients as evidenced by the recent problems reported with New England Compounding Center. As we stated in our report, our intent was not to address the pros and cons of compounding a product in a pharmacy, but rather to address some clinically relevant issues regarding compounded 17-OHPC formulations. Our assessment of potency was primarily directed at addressing the question of drug loss over time either due to chemical degradation of 17-OHPC or adsorption/absorption in/onto plastic containers.

All of the samples tested were assayed for 17-OHPC concentration in a single high performance liquid chromatography (HPLC) run in 1 day. We used a specific and sensitive HPLC methodology for measurement of the concentration of 17-OHPC in the compounded products. The intraday coefficient of variation at the concentration tested after dilution of the product was 1.3%. Therefore changes in concentration of <2% can be detected by the assay used. The assay that was used was more than sufficient to yield data for the objectives of our study.

We also conducted sterility and endotoxin testing (United States Pharmacopeia method), to show that products can be prepared without preservatives or with an alternate preservative. We obtained all the products from the same pharmacy in different final containers with and without preservatives (2 different ones). We found no microbial contamination in any of the products. Low level of endotoxin (within acceptable limits) was only seen in the samples tested 19 weeks after preparation from multidose glass vials, which were sampled repeatedly. The 19-week period over which samples were tested is much longer than the time period required for the patient to consume the dispensed product. Generally compounded 17-OHPC is dispensed in 5-mL containers and is therefore consumed within 5 weeks. The key point is that the products in our analysis were sterile in all the containers tested.

The intent of this study was not to analyze impurities in the compounded product from a single compounding pharmacy. We have in fact conducted another study where we have measured not only the content but also impurities in products compounded by various pharmacies. We hope to submit that report soon.

We are aware of the changing Food and Drug Administration (FDA) positions on compounded 17-OHPC and we reiterate that our objective in this study was not intended to address the merits or risks of a compounded product but to focus on whether plastic containers absorb 17-OHPC to such a degree that the product should not be dispensed in such a container, and if selection of a preservative impacts the product and its microbiological contamination status. This information may be useful to compounding pharmacies that compound 17-OHPC for reasons that are in keeping with FDA guidelines. In any case, whether a product is prepared in a compounding pharmacy or in a manufacturing site, appropriate quality control measures should be in place and they must be enforced for patient safety.