| The purpose of method development is to establish | | | | ensures the samples are sufficiently clean and |
| the applicability of an analytical method for its | | | | therefore able to maintain the shelf-life of the |
| intended use on a certain sample. There are many | | | | analytical instrument used. If unsatisfactory results |
| tests that need to be carried out in the | | | | are obtained, some adjustment has to be made to |
| pharmaceutical field, such as assay, dissolution, | | | | the method. For example, for a method developed |
| identification and related substance. Each of these | | | | using high performance liquid chromatography (HPLC), |
| tests, particularly the quantitative analysis has to be | | | | adjustment can be made to various stages of the |
| developed for its fit for use before approving it for | | | | analysis such as sample preparation, mobile phase and |
| routine application. | | | | the stationary phase. The extensiveness of the |
| How to go about developing a method? Usually the | | | | method development work depends on the |
| first step is literature search. This step includes the | | | | complexity of the sample as well as the instrument |
| reviewing of analytical methods from monographs, | | | | used. |
| scientific journals, drug suppliers and analytical | | | | After development stage, the method has to be |
| instrument companies. For some drugs, the content | | | | validated for the parameters below: |
| can be analyzed employing various methods, for | | | | Linearity refers to the relationship between the |
| instance, high performance liquid chromatography | | | | test results and the concentration of the drug |
| (HPLC), ultra-violet spectrophotometer and titration. | | | | analyzed |
| Therefore, it is important to review the available | | | | Range is the maximum and minimum |
| methods according to its application. Examples of | | | | concentration levels that have been proven to have |
| parameters in a method that can be evaluated are its | | | | accuracy, precision and linearity |
| sensitivity, specificity and available resources. Usually | | | | Accuracy measures the closeness of the test |
| for a pharmaceutical manufacturing company, | | | | results to the true value |
| methods from monographs are preferred due to its | | | | Precision is related to both the instrument and |
| validity. However, recently, the requirement to | | | | method. This parameter measures the closeness of |
| validate monograph methods is increasing. | | | | the test results to each other |
| After selecting the most suitable method, the | | | | Specificity refers to the ability of the method to |
| laboratory personnel need to try out the method. | | | | separate the analyte from other ingredients present |
| During this phase, applicability of the method in terms | | | | in the sample |
| of sample preparation and analytical instrument set up | | | | Sensitivity is the parameter pertaining to the |
| is evaluated. Sample preparation is important to | | | | ability of the method to quantify and detect the |
| ensure accurate and reproducible results. It also | | | | lowest amount of the analyte. |