Near-Infrared Spectroscopy in the Quality Control Laboratory of a Pharmaceutical Company

Transcription

1 FT-NIR SPECTROSCOPY application note Near-Infrared Spectroscopy in the Quality Control Laboratory of a Pharmaceutical Company An evaluation of a new technique for identification of raw materials and blinded study materials Dr. Peter Hofstetter of Werthenstein Chemie AG Dr. Joachim Oelichmann of PerkinElmer Instruments Introduction In the pharmaceutical industry, checking the identity and conformity of materials is one of the main tasks of the analytical lab. Nearinfrared spectroscopy is gaining importance as a tool for compound identification because it is fast, simple to use, and requires little or no sample preparation. Identification tests are mainly performed for: Raw Materials Biotech Operation, Chemical Pilot Plant, and Clinical Manufacturing. Clinical Study Material Identification of blinded study material for correct packaging according to treatment groups of the Master code i.e. active, placebo, and competitor s products). Accurate identification of compounds using NIR spectroscopy The near-infrared region had not traditionally been used analytically because complex molecule vibrations and overtones are abserved. This can lead to spectra that are not simple to predict or understand. From a NIR spectrum, the molecular structure cannot be predicted, however, each compound does have a unique NIR spectrum. A compound can be identified by comparing the sample spectrum with a reference spectrum. The main advantage of using NIR rather than conventional IR spectroscopy is, that undiluted samples can be measured directly. The instrument s reflection mode allows compounds to be identified - even through the outer package (e.g. a sample in a glass bottle, a capsule in a blister pack). Figure 1 shows such a simple measurement of a powder sample in a glass vial. The measurement takes only a few seconds with automatic data handling. Various compounds with small spectral differences can be confidently identified with the system s built-in chemometrics SIMCA software. Figure 1: Powder sample being placed on the Spectrum One (NTS), near infrared testing system, featuring the NIRA sampling module

2 The analytical laboratory is under pressure to perform more tests European GMP guidelines require that each container of a raw material be identified: "There should be appropriate procedures or measures to assure the identity of the contents of each container of starting material" (EU cgmp guidelines, chapter 5.30). This results in a substantial amount of work for the Biotech operation because raw materials are often delivered in several small units or containers. Additionally the number of clinical studies has drastically increased resulting in an increase in requests for materials identification. Figure 2 show a statistical analysis of the number of identification requests between 1983 and 1996 where each request consists of several identification checks. Assuring the identity of incoming raw materials Raw material identification by NIR is performed by comparing the sample s spectrum with a database containing reference spectra of all previously identified raw materials. The system performs a spectral comparison (COMPARE Function) and ranks the findings by similarity; from 1.0 or completely identical, to 0.0 or completely different. Lactose is a good example of how NIR can accurately compare the NIR spectra of very similar compounds. Lactose is used as formulation ingredient in both the hydrous and anhydrous forms. The NIR spectra of the two compounds can easily be distinguished because the hydrate form shows the -OH overtone vibrations. The NIR spectra of four batches of hydrous lactose and four batches of anhydrous lactose is shown in Figure 3. Figure 2: Analytical requests are on the rise at the pharmaceutical laboratory. Figure 3: NIR comparison of hydrous and anhydrous lactose.

3 Figure 4 is another example of using NIR to distinguish between polyethylene glycol compounds with different chain lengths and molecular weights. The sample materials were kept in brown glass bottles, and no preparation was performed before testing. The measurements were taken by placing a few ml of sample into a cup and scanning in transflectance mode using the system s reflectance sampling system. As a last example we have compared the NIR spectra of SCH dihydrochloride with that of SCH dihydrochloride dihydrate. Also in this example the two forms can easily be distinguished by NIR (Figure 5). Verifying a sample tablet s content simplifying this critical process for clinical studies Packaging double blind clinical study material is a critical step as all medications (active, placebo, and competitors products) look identical. Great care must be taken in order to prevent the mix-up of the products. As a final check, samples from one patient unit of each medication group are checked by quality control for identity. HPLC is the currently used to perform this verification. The HPLC method requires that the content of several samples (capsules) are dissolved in an appropriate solvent. A standard solution is prepared with a reference standard. A HPLC unit is set up, equilibrated for the methods, a system suitability check performed. Only then can the samples be analyzed. Thousands of units are measured this way by the QC lab. A simpler method would drastically reduce the efforts for these determinations. Figure 4: Using NIR to distinguish between polyethylene glycol compounds. Figure 5: Using NIR to distinguish between dihydrochloride and dihydrochloride dihydrate of an active

4 Figure 6: Identification of Ribavirin 200 mg capsule versus a placebo capsule Figure 7: Differentiation of Mometasone active powder from placebo powder NIR is an alternate technique that simplifies the sampling and method development process. The pharmaceutical sample is placed on the sample window and measured. Since NIR radiation penetrates the product a few millimeters before it s reflected, the compound within a capsule shell can be identified without opening the shell. In the case of the identification of an active capsule from a placebo capsule the spectrum of the active capsule is the sum of the spectra of the gelatin capsule and its content (excipients and active drug), while the spectrum of the placebo capsule is the sum of the spectra of the gelatin capsule and excipients without active drug. Small spectral differences can easily be distinguished by this method. The Spectrum One NTS built in chemometrics SIMCA software allows it to make a statistically significant assignment of a sample spectrum of the active or placebo group. An example of using NIR in this manner is the identification of Ribavirin 200 mg capsule versus a placebo capsule. The spectrum of the active capsule and the placebo capsule are significantly different (Figure 6). Another example is the identification of the content of Mometasone dry powder inhalers. In this case some powder was removed from the inhaler by opening the inhaler and placing it on a small glass plate for measuring. All different strengths of Mometasone inhalers contain the same powder, only the dosing device has a different volume. Differentiation of active powder from placebo powder is not simple, but there is a typical absorbance band in the active powder at 6120 cm -1, which is missing in the placebo powder (Figure 7).

5 Using chemometrics software (SIMCA) the spectra of active and placebo powder are reduced each to a datapoint in a x,y coordinate system. The system is calibrated by measuring 5 to 10 active and placebo capsules. The x,y coordinates of the datapoints of one medication group (active or placebo) should then lay within a certain range, with no overlapping of the ranges between active and placebo. The more different the spectra of active and placebo are, the bigger is the distance between the datapoints in the x,y coordinate system. Figure 8 shows this graphically for the case of the Mometasone DPI s. When a sample to be identified is measured, the spectral data are reduced in the same way to a x,y coordinate and the sample gets assigned to one of these groups, or its identification is not confirmed, if the x,y coordinates are outside of a certain range of the two groups. The report in Figure 9 shows such an assignment. We have measured randomly about 20 samples and each of them has been correctly identified. This example shows the limits of such a system. Only a NIR instrument with good resolution can distinguish small spectral differences. The other NIR instrument tested was not able to measure such small spectral differences as that instrument uses a spectral resolution of 25 cm-1 (compared to the instrument from PerkinElmer, which can be configured to a resolution of 2 cm-1). We also learned that this method is not applicable, when the active component in the medication unit is less than about 5% of the total unit weight, as in that case the spectral differences between active and placebo samples are too small. This is for example true for all biotechnological products and most of the solutions. Figure 8: The application of chemometrics software determines the clusters of the active and the placebo powders Figure 9: Classification report for the identification of Mometasone active powder

6 Approval of NIR as an accepted method by the health authorities NIR finds more and more applications in a GMP environment. It is often used in pharmaceutical companies for compound identification. The new issue of the European Pharmacopeia even has a separate chapter describing this technique. This technique is now a widely accepted method accepted by IKS and the Swiss Health Authorities. Demonstrating system performance and suitability are also important aspects of gaining regulatory approval. The NIR instrument has a built in calibration program, which calibrates the wavelength and transmission within a few minutes with a built in reference. A corresponding report is printed out. Compared to many other instruments this calibration is fast and very simple. It is recommended to perform this task about every six months. Conclusion After the tests all participants were surprised, how universal such an instrument can be used. The time reduction for raw material or study material identification is very significant as no sample preparation has to be performed and the measurement and reporting is performed within one to two minutes. Such an instrument could heavily reduce the workload in the lab. Get more connected. PerkinElmer Instruments 761 Main Avenue Norwalk, CT USA Tel: or (+1) Fax: (+1) U.K., PerkinElmer Infrared Spectroscopy Business PerkinElmer is a trademark of PerkinElmer, Inc. Spectrum One is a trademark of PerkinElmer Instruments LLC. Post Office Lane, Beaconsfield, Bucks, HP9 1QA Tel: (01494) Fax: (01494) / PerkinElmer, Inc. Printed in U.S.A. D-6283 KG030005