COMPENDIAL TESTING

PREPARED BYKETAN MISHRA MPHARM QARA SEM -2ROLL NO -5

GUIDED BY MISS KRUPA THULLAASSIST. PROF.M PHARM QA DEPARTMENT

CONTENTS• INTRODUCTION

• HISTORY OF THE UNITED STATES PHARMACOPEIA

• U.S. PHARMACOPEIA–NATIONAL FORMULARY

• THE PHARMACOPEIAL FORUM

• COMPENDIAL TESTING FOR FORMULATED PRODUCTS AND ACTIVE INGREDIENTS • IDENTIFICATION OF ACTIVE PHARMACEUTICAL INGREDIENTS

• IDENTIFICATION TESTS SPECIFIC TO ACTIVE INGREDIENTS

• REFERENCE

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compendial testing Comprises all of the analytical testing required to prove the identity, efficacy, and safety of drug products before they are packaged or distributed.

At the Suffern site the manufacturing facility for Novartis Pharmaceuticals Corporation (NPC) in the United States, the quality assurance laboratories are responsible for testing raw materials, active ingredients, and formulated products.

Introduction

a variety of analytical techniques are used ranging from very simple physical testing to complex chromatographic separations.

the degree of testing that a product requires depends on the characteristics of the compound, the number of the components in the product, and the dosage form

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A result of the efforts of Dr. Lyman Spalding of New York City in 1817.

The United States would be divided into four districts and delegates would represent each of the medical associations and schools situated within it.

Each district would hold a convention at which time a pharmacopeia would be drafted, and representatives were appointed to attend a General Convention that would be held in Washington, DC.

At the General Convention, the four district pharmacopeias would be compiled into a single National Pharmacopeia.

Through the authority of the Medical Society of the State of NewYork, Dr. Spalding’s plan went into effect.

HISTORY OF THE UNITED STATES PHARMACOPEIA

Cont….

• The first U.S. Pharmacopeial Convention assembled in Washington, DC, on January 1, 1820, and on December 15, 1820, the first U.S. Pharmacopeia was published.

• At this first convention, it was decided that a revised USP edition would be published every 10 years.

• In 1900 the decision was made to issue supplements to the USP in the interim between new editions, and in 1940 the period for new editions was changed from every 10 years to every 5 years.

• The primary objective of the USP is to compile a select list of pharmaceuticals every 5 years, including medicinal substances and preparations that are still covered under patent rights.

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U.S. Pharmacopeia–National Formulary

• The pharmacopeia contains monographs, procedures for general tests and assays, and a section on reagents and solutions for drug substances, drug products, nutritional supplements, and excipients.

• The products can be labeled as “USP,” which indicates compliance with the specifications designated in the pharmacopeia.

• The USP works closely in conjunction with the FDA, the pharmaceutical industry, and health professionals in establishing their standards, which are enforceable by the FDA and the governments of more than 35 countries.

• Failure to comply with USP–NF standards and test methods can result in products that are adulterated, leading to a variety of negative outcomes including FDA recalls and warning letters.

• USP also provides reference standards.• USP also holds various events like “Children and Medicines” and

“Communicating Risk to Patients.”

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The Pharmacopeial Forum

• It provides the arena for proposed and forthcoming revisions to the USP–NF.

• It is published six times per year by the USP, allowing public review to official pharmaceutical standards before they become effective.

• It encourages a free exchange of ideas and information among the scientists involved in the development of analytical test methods.

• It is divided into two main sections: Pharmacopeial Previews and In-process Revision.

The Pharmacopeial Forum

Pharmacopeial Previews

• Contains new methods that are being presented to the industry for the first time.

• USP Monographs, NF Monographs, and General Chapters for chemical tests and assays are included within this section.

• New monographs may be proposed for new drug substances or new dosage forms.

• The General Chapters section contains test methods specific to particular drug substances or dosage forms.

• Following a method’s debut in the Pharmacopeial Previews section, comments may be submitted to the Subcommittee regarding the proposed monograph or method.

• These comments would then appear in the In-process Revision section of the Pharmacopeial Forum.

The Pharmacopeial Forum

In-process Revision

• Contains the actual corrections and changes suggested by the industry readers to improve the proposed monograph or method.

• Therefore, it contains not only the original wording from the Pharmacopeial Previews, but also the proposed changes, allowing the reader to see the history of the review process.

• Following receipt of comments on monographs or methods, they are reviewed by the Subcommittee who will in turn propose them for official adoption into the USP.

• Once the Division of Standards Development (DSD) Executive Committee gives approval, the Board of Trustees approves publication and that monograph or method will be slated for the next Supplement to the USP or USP–NF edition.

The Pharmacopeial Forum

• Typical quality control (QC) laboratories test raw materials, active ingredients, and finished products with different kinds of testing being required for each.

• The testing for most raw materials follows compendial methods whereas testing for most finished products does not.

• For new drug products containing new drug substances, there are no compendial methods.

• Once marketing approval is granted for a new product by the appropriate regulatory agency, the testing methods used in the development of the product will be incorporated into the USP as the official compendial methods.

• Other situations exist in which a new product contains a previously approved drug substance that may have already-existing compendial methods.

• The existing compendial methods may not be appropriate for the new product and new methods may need to be developed.

COMPENDIAL TESTING FOR FORMULATED PRODUCTS AND ACTIVE INGREDIENTS

• When a new product is being considered for marketing in more than one country, besides the FDA, the regulatory agency for the United States, applications will also be submitted to the regulatory agencies of other countries. Japan, Britain, and Europe each have their own pharmacopeias, testing methods, and specifications.

• When new drug applications (NDAs) are submitted, sometimes, as we will see, the regulatory agencies will not agree on the degree of testing, and additional testing could be required for products to be distributed in certain countries.

• In recent years, there has been an effort to harmonize compendial requirements with significant progress being made in certain areas.

• The products discussed were chosen because they have unique and interesting testing procedures and intriguing molecular structures and are marketed in a variety of dosage forms.

• Particular attention will be given to USP requirements.

COMPENDIAL TESTING FOR FORMULATED PRODUCTS AND ACTIVE INGREDIENTS

• Four analytical tests that are considered universal by the FDA for formulated products: description, identification (ID), assay, and impurities.

• Descriptions of active ingredients and raw materials just describe the physical appearance of the substance.

• These tests represent the minimum testing requirements for a batch of drug product to be released by the quality assurance laboratory.

• Additional tests may be required depending on the characteristics of the particular drug substance and the dosage form.

• For drug substances that are marketed in more then one dosage form, different methods or variations of existing methods might be needed for each.

• In most testing laboratories, in-house quality standards (QS) exist for each product and strength.

• The QS may also contain sample HPLC chromatograms, UV/visible spectra, and IR spectra to aid the analyst in carrying out each test.

Descriptions of Active Ingredients and Solid Oral Dosage Forms

• A description test is a qualitative physical description of the drug product including the dosage form and any visual characteristics: size, shape, color, and any other identifying markings.

• The description test is critical and if it is incorrect, that particular batch of product is immediately considered defective.

• Description testing is not included in the USP because the physical description of products is unique to the manufacturer.

• Generic products containing the same drug substance have their own identifying markings different from those of the branded product.

Identification of Active Pharmaceutical Ingredients

• To confirm the identity or presence of the active ingredient by employing a variety of analytical techniques and methods.

• For drug formulations, the drug substance may need to be extracted from the dosage form. New techniques such as near-IR spectroscopy may eliminate the need to isolate the active ingredient.

• Once the pure compound is obtained, a spectroscopic technique such as UV, IR, or melting point will be used to compare the sample identity to that of a standard that has been similarly prepared.

• The characteristics of the compound will help define which type of spectroscopy will be most useful.

• The goals of identification testing is that it must be specific enough to distinguish between compounds with similar structures including starting materials and degradation products.

• In some cases, nonspecific methods are sometimes used in conjunction to obtain a positive ID.

Identification of Active Pharmaceutical Ingredients

• HPLC is a commonly used analytical technique with the retention time being indicative of the compound.

• However, HPLC retention time is not usually regarded as specific for identification testing, but can be used in conjunction with other tests such as thin-layer chromatography (TLC), IR spectroscopy, UV/visible spectroscopy, or other physical tests such as melting point. When retention time is used, the standard and sample must elute at similar times.

• Many drug substances are used in the form of a salt. The identification of these materials may also include a test for the specific counterion used.

• Common counterions used in pharmaceuticals are sodium, chloride, and pamoate ions.

Identification of Active Pharmaceutical Ingredients & solid dosage form

• Metoprolol tartrate is a synthetic drug substance used for the treatment of hypertension. The drug substance is a 2:1 salt that contains a racemic mixture of optical isomers of metaprolol and naturally occurring dextrotartaric acid.

• Both the active ingredient and the tablet form have different testing requirements.

• Metaprolol tartrate tablet testing uses UV and IR spectroscopy for metaprolol ID, TLC for the tartrate ion ID, and HPLC retention time for identification.

• The IR spectroscopy test is carried out by dissolving approximately 136mg of finely ground tablets and in 25mL of water with 4mL of ammonium hydroxide (1:3). After extraction with chloroform, the organic layer is dried over anhydrous sodium sulfate, evaporated, and placed in a freezer to congeal the crystals. Once formed, the crystals are triturated with potassium bromide and used in pellet form to obtain an IR spectrum that is then compared to that of a standard similarly prepared.

Metoprolol tartrate

The TLC test for the tartrate ion• Sample and standard solutions of equal concentration are spotted on a

chromatography plate & allowed to develop. If the substances in the sample and standard solutions are the same, they will have identical Rf values.

• Most organic compounds are not colored and do not fluoresce within the visible light range, i.e., are not visible to the naked eye and require some form of visualization.

• In most cases, UV light enables the analyst to see the spots and calculate the Rf value.

• In contrast, the injectable form of metoprolol tartrate requires only IR identification with a procedure almost identical to that for the tablet form.

• The only difference is that a specific volume of the injectable solution, which is already dissolved in water, is used in the extraction. This is a good example of a situation where only a slight modification of the analytical procedure was needed for two very different dosage forms.

• Carbamazepine is an analgesic and anticonvulsant distributed as tablets, chewable tablets, and an oral suspension.

• The active ingredient, tablet, and oral suspension dosage forms have distinctly different identification procedures.

• The carbamazepine active ingredient has an identification test unique for testing raw materials, X-ray diffraction.

• Each crystalline form of a compound yields its own unique X-ray diffraction pattern, which is considered a form of identification. X-ray diffraction patterns can be obtained from a single crystal or from a sample of powder and then can be used for quantitative and qualitative analysis of the substance.

• For the tablet form of carbamazepine, an IR spectrum is obtained with a procedure slightly different from that for metaprolol. To carry out the test, 360mg of powdered tablets is boiled in 15mL of acetone, filtered, and evaporated to around 5mL using a stream of nitrogen. Cooling in an ice bath gives rise to crystals, which after filtration and drying are used in a Nujol mull to obtain an IR spectrum.

Carbamazepine

• Terbutaline sulfate, which is a synthetic β2-adrenoceptor that is used as a bronchodilator for the treatment of asthma.

• The compound is available in inhalation aerosol, injectable, and tablet dosage forms. The inhalation aerosol is the most unique of the three dosage forms.

• The aerosol consists of a suspension of fine terbutaline sulfate in a pressurized aerosol container equipped with a metered dose valve and oral inhalation actuators.

• To extract the sample from the aerosol, 10 filled containers are chilled to −75◦C in an acetone–dry ice mixture for 15–20 min. After the tops are removed and the containers are allowed to sit, the contents are poured into a beaker. A portion of this mixture is extracted into chloroform and filtered through a medium-porosity sintered glass funnel. After the residue is washed with chloroform and allowing to air-dry, the crystals are then used to form a KBr pellet and obtain an IR spectrum.

Terbutaline sulfate

• For terbutaline tablets, TLC is used to identify the active ingredient. • The tablets are dissolved in dilute ethanol and centrifuged. The

insoluble excipients fall to the bottom and the ethanol solution containing the active ingredient is used to spot the TLC plate. The plate is developed using a mixture of cyclohexane, isopropyl alcohol, and formic acid as eluants, and air-dried.

• In contrast to the tartrate TLC analysis for metaprolol, which used UV light to visualize the spots, the terbutaline TLC analysis uses a specific reagent sprayed onto the plate to assist in visualizing the spots.

• After the plate is sprayed with a spray reagent, the spots appear colored with the color change indicative of the class of compound and the reagent used. In the case of terbutaline, a phenol derivative, 4-aminoantipyrine–potassium ferricyanide is used. Separate solutions of 4-aminoantipyrine and potassium ferricyanide are prepared and the plate is sprayed with each.

• Exposing the sprayed plate to 25% ammonium hydroxide results in red-orange to pink spots indicative of phenols. Numerous spray reagents are known and are specific for different classes of compounds.

Identification Tests Specific to Active Ingredients

• Identification tests for pure drug substances can be different from those for formulated products. Many times, tests for the specific counterion drug substance will be performed on the active ingredient. These tests are very general and oftentimes can follow official compendial methods.

• Imiprimine hydrochloride is the original tricyclic antidepressant and is a member of a class of compounds known as dibenzazepines.

• Imiprimine is a hydrochloride salt available in tablet and injectable dosage forms.

• The counterion for imiprimine hydrochloride, chloride, is identified as part of the active ingredient.

• To carry out the test, the sample powder is dissolved in alcohol, and 2 N nitric acid is added along with 3 drops of a silver nitrate test solution.

• A white precipitate of silver chloride is formed, which dissolves upon addition of ammonium hydroxide, confirming the presence of the chloride ion.

• As chloride identification is used for the testing of the drug substance, it is not required for the formulated product.

• Imiprimine is also available as a pamoate salt. The QS ID test uses TLC to identify the pamoate ion.

• A standard solution of pamoic acid is prepared by dissolving it in a sodium hydroxide solution. The pamoate ion is extracted from the dosage form by dissolving the tablet powder in a sodium hydroxide solution and extracting the active ingredient with chloroform. The pamoate ion remains in the water layer and the chloroform layer is discarded.

• Both the sample and standard solution are spotted on a TLC plate and eluted with a mixture of acetic acid, ethyl acetate, water, and hydrochloric acid.

• The plate is developed, dried, and sprayed with a potassium dichromate-detecting reagent to visualize the spots.

• The simple ion-exchange reaction like that used to identify simple counterions (e.g., chloride or sulfate) cannot be used for the pamoate ion

Imiprimine hydrochloride Imiprimine pamoate

• The test for ID of the counterion associated with terbutaline sulfate is similar to that for imiprimine HCl. A water solution of terbutaline sulfate is prepared and acidified with hydrochloric acid. Upon addition of a few drops of barium chloride solution, a white precipitate forms, which indicates barium sulfate.

• The drug substance reserpine is an optically active molecule containing six asymmetric carbons. One of the properties unique to optically active compounds is their ability to rotate plane-polarized light.

• The degree of rotation depends on the concentration of the sample and the length of the sample path.

• The specific rotation, denoted [α]D, takes these parameters into consideration and is a measure of a compound’s ability to rotate plane-polarized light.

• All pure optically active compounds have their own specific rotation, which can be used to identify them. The angular rotation of reserpine is determined using a solution of known concentration in chloroform.

• The angular rotation is then measured using a polarimeter at room temperature and compared with a standard.

• Both the physical and chemical properties of the molecule and dosage form challenge the analyst by requiring expertise in wet and instrumental chemistry to correctly identify the material under study.

REFERENCE

• Handbook of modern pharmaceutical analysis, Edited by Satinder Ahuja and Stephen Scypinski, page no- 325-333.

REFERENCE