An 348:extraction of anthelmintic drugs from a veterinary formulation using accelerated solvent extraction (ase)

Application Note 348
Extraction of Anthelmintic Drugs from a
Veterinary Formulation Using Accelerated
Solvent Extraction (ASE®)
INTRODUCTION
EQUIPMENT
Isolation of the active drug from some veterinary Dionex ASE 200 Accelerated Extractor with Solvent formulations can be difficult because the matrix is often complex. These difficulties were traditionally solved by 11-mL stainless steel extraction cells (P/N 055422) extracting with a wrist-shaker method, sonication, or Soxhlet. Although these techniques produce adequate Dionex collection vials, 40 mL (P/N 048783) results, they are very labor intensive and use large Analytical balance (accurate nearest 0.0001 g or better) amounts of solvent. The time required for these methodscan cause bottlenecks in the sample preparation area Sand (Ottawa Standard, Fisher Scientific, Cat. No. S23-3) and solvent use can cost the laboratory thousands of dollars in unwarranted expenses per year.
PTFE syringe Filter, 0.2 µm (Fisher Scientific) Accelerated Solvent Extraction (ASE) is an auto- mated extraction technique that uses the same solventsas traditional extraction methods but in significantly REAGENTS
smaller amounts and with minimal analyst exposure.
ASE achieves equivalent or better results in a fraction ofthe time by using increased temperature and pressure toenhance the kinetics of the extraction process. Thisentire process is fully automated and allows the unat- tended extraction of up to 24 samples.
This application note describes the extraction of the two active species of ivermectin (H2B1a and H2B1b), an anthelmintic drug, from a veterinary formulation contain- ing dried meat products. This formulation is used to treat household cats and dogs for heartworm disease. Figure 1 shows the chemical structure of ivermcetin.
Component B
R = CH2CH3
Component B1b
Figure 1. Chemical structure of ivermectin.
Application Note 348
SOLVENTS
Table 1. ASE Recovery of Ivermectin from Spiked
Placebo Samples
(All solvents are pesticide-grade or equivalent and Target* %
EXTRACTION CONDITIONS
* Shows a range of 50–150% of the target concentration (0.9 µg/mL) Table 1 shows the results of extracting placebo preparations spiked with a varying range of ivermectinconcentrations (50–150%). The average recovery for all SAMPLE PREPARATION
The tablet should be finely ground using a food Table 2 shows the precision of the ASE method. Six processor or coffee grinder to a powder that can pass preparations from one lot of HEARTGARD® Chewables through a Tyler 10 sieve. Accurately weigh out approxi- for Cats were extracted and analyzed. The average mately 0.5–1.5 g of the powder and blend with 1.5 g of percent recovery for these six preparations was 102.3% Hydromatrix using a mortar and pestle. Transfer the with an RSD of 0.90%. These recovery and precision mixture to an 11-mL stainless steel extraction cell values are as good or better than observed with tradi- containing a cellulose filter. Top off any dead space in the cell with Ottawa sand. Prepare any other tabletsamples and load them into extraction cells.
EXTRACTION PROCEDURE
Table 2. ASE Method Precision Summary: Extraction
of Ivermectin from HEARTGARD Chewables for Cats
Place the cells onto the ASE 200. Label the appro- priate number of collection vials and place these into the Preparation
% Recovery
carousel. Set up the method suggested above and begin the extraction. When the extraction is complete, theextract can then be diluted to the desired volume and passed through a 5-mL alumina cartridge. Finally, filter the extract into an HPLC vial through a 0.2-µm PFTEfilter and analyze using HPLC.1 RESULTS AND DISCUSSION
Sample preparation is critical to good recoveries.
Grind the samples to a uniform particle size to ensure proper permeation of the solvent into the matrix. Thesample extracts may be somewhat cloudy due to the extractions of fats and other coextractables, so it is impor-tant to pass the extracts through a short column of alumina.
2
Extraction of Anthelmintic Drugs from Veterinary
Formulation Using Accelerated Solvent Extraction (ASE)
CONCLUSIONS
ACKNOWLEDGEMENTS
These results confirm that ASE is comparable to We would like to acknowledge the work of Andreas traditional extraction methods for the difficult extrac- Abend and his colleagues at Merck & Co. Inc.
tions of active drugs from veterinary formulations.
Traditional extraction methods usually take from one to REFERENCES
several hours for each sample and require large amounts of solvent. With ASE, the extraction time is cut to Wuelfing, W. P. “Development and Validation of an approximately 15 min per sample and uses only 25–30 Automated Extraction Method (Accelerated Solvent mL of solvent. In addition, the ASE 200 can extract up Extraction®) and a Reverse-Phase HPLC Analysis to 24 samples, sequentially, without user intervention.
Method for Assay of Ivermectin in a Meat-Based
Chewable Formulation.” Pharm and Bio Med
Analysis 2003, 31, 1177–1183.
HEARTGARD is a registered trademark of Merial.
ASE is a registered trademarks of Dionex Corporation.
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