Objective
17-alpha hydroxyprogesterone caproate (17-OHPC) is available both as an Food and Drug Administration (FDA)–approved medication and as a product prepared for individual patients by compounding pharmacies. Compounding pharmacies may omit the preservative that is used in the FDA-approved formulation or use an alternate preservative and may dispense 17-OHPC in containers that differ from the FDA-approved product. The objective of this study was to assess the stability and the microbiologic and pyrogen status of 17-OHPC formulations under various compounding and dispensing conditions.
Study Design
17-OHPC was prepared by a local compounding pharmacy. The formulations that were prepared included 1 identical to the FDA-approved product with benzyl alcohol as a preservative, 1 with benzalkonium chloride as a preservative, and 1 without a preservative. These various formulations were dispensed into either single-dose 1-mL plastic syringes or glass vials or 10-mL glass vials. The concentration of 17-OHPC and microbial and pyrogen status were evaluated at various time intervals over the ensuing 19 weeks.
Results
The concentration of 17-OHPC did not change over the duration of study, regardless of the dispensing medium that was used or the absence or presence of any preservatives. The preparations remained microbe- and pyrogen-free during the study period, regardless of the dispensing medium that was used or the absence of presence of any preservatives.
Conclusion
Products that contained 17-OHPC tested in this study were quite stable over the 19-week period of study in different dispensing containers and in the absence or presence of a different preservative. The compounded products remained sterile and pyrogen-free during the period of observation.
Seventeen-alpha hydroxyprogesterone caproate (17-OHPC) has been used to reduce the rate of recurrent preterm birth since the 2003 report of Meis et al from the Maternal-Fetal Medicine Units (MFMU) Network trial that demonstrated a 33% reduction in preterm birth with that therapy. Use of the medication has increased after the endorsement by the American College of Obstetricians and Gynecologists and the March of Dimes and with coverage of the cost of medication by many insurers. Although the Food and Drug Administration (FDA) recently provided conditional approval of a product that is identical to the one used in the MFMU study, compounding pharmacies are not prohibited from continuing to compound 17-OHPC, and many continue to do so based on the recent FDA statement that “FDA does not intend to take enforcement action against pharmacies that compound hydroxyprogesterone caproate based on a valid prescription for an individually identified patient unless the compounded products are unsafe, of substandard quality, or are not being compounded in accordance with appropriate standards for compounding sterile products.” Some compounding pharmacies have prepared formulations of 17-OHPC without preservatives because of the caution issued by the FDA about the administration of benzyl alcohol to pregnant women. The impact of not using a preservative in the formulation of 17-OHPC is unclear. Additionally, the medication most often is dispensed in multidose glass containers to minimize absorption of the 17-OHPC that is believed to occur with the use of plastic containers. Single-dose plastic containers provide a benefit to the user in that measurement errors by the patient are eliminated and that issues related to sterility are minimized when compared with multidose vials. Whether dispensing 17-OHPC in single-dose plastic containers leads to lower amount of the drug in solution because of absorption problems or the stability and sterility of such products has not been evaluated. Our objective was to evaluate the impact of time, preservative, and dispensing modality on the stability, sterility, and pyrogen status of compounded 17-OHPC formulations. This study was institutional review board exempt because it involved no patients or biologic materials.
Materials and Methods
Pharmaceuticals and drug preparation
17-OHPC, benzyl alcohol, benzalkonium chloride, and benzyl benzoate were purchased from Professional Compounding Centers of America (Houston, TX). Castor oil was purchased from Paddock Labs (Minneapolis, MN). Stock solutions and working standards that were used for the analysis of the chemical stability were dissolved in methanol and stored at −20°C. Analytical-grade buffer reagents and solvents were purchased from Fisher Scientific (Pittsburgh, PA).
We used a local pharmacy to prepare 6 experimental formulations that reflect several options that are afforded to the compounding pharmacies in the preparation of 17-OHPC ( Table 1 ). Conditions differed by the preservative that was used (benzyl alcohol 2%, benzalkonium chloride 0.1%, or no preservative) and the dispensing medium (10-mL glass multidose vial or 1-mL glass vial or 1-mL plastic syringe). Appropriate amounts of 17-OHPC powder were dissolved fully in benzyl benzoate in the presence or absence of the preservatives, benzyl alcohol, or aqueous benzalkonium chloride. Castor oil was then added to bring the final concentration of 17-OHPC to 250 mg/mL. Concentrations of benzyl benzoate and castor oil in the 6 formulations were 46% and 44-54%, respectively. Each solution was filtered (pore size, 0.22μm) to remove particulate matter and any bacteria.
| Formulation | Container | Preservative |
|---|---|---|
| 1 | 10-mL multidose glass vial | Benzyl alcohol |
| 2 | 10-mL multidose glass vial | Benzalkonium chloride |
| 3 | 1-mL plastic syringe | None |
| 4 | 1-mL glass vial | None |
| 5 | 1-mL plastic syringe | Benzalkonium chloride |
| 6 | 1-mL glass vial | Benzalkonium chloride |
All solutions were prepared under a laminar flow hood. We assessed transparency and color of the solutions weekly. Under formulations 1 and 2, three 10-mL glass vials each were prepared. Under formulations 3, 4, 5, and 6, twelve 1-mL plastic syringes and 12 1-mL glass vials were prepared for each condition to allow measurement of 17-OHPC concentration to be performed in triplicate at baseline and at several time intervals after preparation.
Content analysis
Timing of drug stability and concentration testing
The concentration of 17-OHPC in each formulation was determined immediately after preparation. Testing was repeated at various times (2, 4, 10, and 19 weeks) after preparation ( Table 2 ). To evaluate the stability of the 17-OHPC, we removed an aliquot of the formulation from each syringe or vial and measured the content of 17-OHPC in that aliquot. Samples from all 6 experimental formulations were tested for drug concentration in triplicate at baseline 2, 4, and 10 weeks after specimen preparation. The 10-mL vials also provided sufficient volume for measurement of concentration in triplicate at 19 weeks.
| Test | Baseline testing | Weeks after drug preparation | |||
|---|---|---|---|---|---|
| 2 | 4 | 10 | 19 | ||
| 17-alpha hydroxyprogesterone caproate concentration | X | X | X | X | X a |
| Microbiology | X b | X b | |||
| Endotoxin | X b | X b | |||
a Testing performed only for conditions 1 and 2 (10-mL multidose glass vials);
b Testing for conditions 1 and 2 performed in triplicate; testing for conditions 3 (1-mL plastic syringe without preservative) and 5 (1-mL plastic syringe with benzalkonium chloride) were performed on pooled specimens.
Timing of sterility and endotoxin testing
Testing to evaluate microbiologic contamination and endotoxin content was performed by Eagle Analytical Services (Houston, TX) in triplicate at baseline then at 10 and 19 weeks on samples from the 10-mL glass vials. Microbiologic and endotoxin testing on the 1-mL containers was limited to the plastic syringes (conditions 3 and 5) because of volume constraints and costs. Testing on samples from the 1-mL plastic syringes was performed at baseline and 10 weeks after sample preparation. We combined fluid from the 3 identically formulated syringes to perform the analyses. Thus, the analyses for microbes and endotoxin from the 10-mL vials were done in triplicate; analyses of the 1-mL syringes were performed on pooled samples from the three 1-mL preparations.
The assays were performed at the intervals indicated in Table 2 ; the samples were tested for the presence of bacteria, fungi, mold, and yeast.
Analytical methods
Drug concentration
High-performance liquid chromatography (Waters 2695 Separations Module attached to Waters 2998 Photodiode Array Detector; Waters Corporation, Milford, MA) with chromatographic separation of various compounds was performed in a 250 × 4.6–mm, 5-μm Symmetry C18 column (Waters Corporation) with an isocratic elution. The mobile phase consisted of methanol/water (90:10, vol/vol delivered at 0.9 mL min −1 ). The column eluents were monitored at 242 nmol/L. The retention times of 17-OHPC was 7.0 minutes. The concentration of 17-OHPC in samples was quantified with a standard calibration curve that ranged from 1.25 ng/mL to 50 ug/mL. The peak area was plotted against the concentration, and a calibration curve was generated with least-squares linear regression analysis. The assay was validated for specificity, precision (coefficients of variation, ≤10%), accuracy (≥92%), and linearity (1.25-50 μg/mL). The limits of detection and the limits of quantitation for 17-OHPC were 5 and 62.5 ng, respectively, on the column.
Microbiology
Sterility testing was performed by Eagle Analytical Services according to the United States Pharmacopeia 14-day membrane filtration sterility test procedure. Testing was performed for bacteria, molds, yeast, and fungi with tryptic soy broth medium and thioglycollate medium at 22.5 ± 2.5°C and 32.5 ± 2.5°C, respectively. Cultures were assessed at days 3, 7, and 14 after plating.
Pyrogenic testing
Endotoxin testing was performed by Eagle Analytical Services according to the United States Pharmacopeia (85) turbidimetric testing procedure. Quantities of endotoxin are expressed in endotoxin units per milliliter (EU/mL). The Pyros Kinetix Incubating Kinetic Tube Reader (Associates of Cape Cod, Inc, East Falmouth, MA) was used to give a detectable endotoxin level down to 0.001 EU/mL.
Results
Concentration and stability of 17-OHPC
The concentration of 17-OHPC was stable throughout the 10-week study period. This finding was independent of the presence of or type of preservative or the dispensing carrier ( Table 3 ). In the 2 vials with 10-mL solutions, sufficient sample was left to assess concentrations of 17-OHPC at week 19. 17-OHPC at this time point remained completely stable. The coefficient of variation within any single condition ranged from 1–4%. There was a difference in measured 17-OHPC at baseline (coefficient of variation, 7%) in the 6 formulations, but the compounded products changed little from the baseline over the duration of study.
