Pharmaceutical Excipients: A review - IJAPBC



IJAPBC ? Vol. 1(1), Jan- Mar, 2012

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INTERNATIONAL JOURNAL OF ADVANCES IN PHARMACY, BIOLOGY AND CHEMISTRY Review Article

Pharmaceutical Excipients: A review

Shilpa P Chaudhari* and Pradeep S Patil Marathwada Mitra Mandal's College of Pharmacy, Thergaon, Pune, Maharashtra, India.

ABSTRACT Excipients play an important role in formulating a dosage form. These are the ingredients which along with

Active Pharmaceutical Ingredients make up the dosage forms. Excipients act as protective agents, bulking agents and can also be used to improve bioavailability of drugs in some instances, the following review discusses the various types and sources of excipients along with their uses, and these can be used for different activities. Specific excipients are best suited for a particular dosage form; the selection criterion for excipients and various interactions that an excipient can undergo during its course of stay in formulation has been discussed in this review. Some excipient interactions can be detrimental and need to be avoided. This has been detailed out in the interaction section. Excipients as like other active pharmaceutical ingredients need to be stabilized and standardized; the following review gives brief information about standardization and stabilization process alongwith the safety evaluation parameters of the excipients. Keywords: excipient, Interactions, co-processed excipients, Standardization.

INTRODUCTION1-5 Many dosage forms formulated today are complex

system containing many other components along with the active pharmaceutical ingredient (API); these compounds are generally added along with the active pharmaceutical ingredients in order to

Protect, support or enhance stability of the formulation:- Most of the times it is observed that the active pharmaceutical ingredient in its pure form does not retain its stability for long which results in its denaturation, or sticking to the container wall thus rendering it unfit, hence in order to stabilize the API excipients are added which aid in maintaining the stability of the product and ensures that API retains its stability for a considerable period of time thus improving the shelf life of dosage formulation.

Bulk up the formulation in case of potent drug for assisting in formulation of an accurate dosage form.

Improve patient acceptance. Help improve bioavailability of active drug:

- Excipients usually help in improving the bioavailability of the active pharmaceutical ingredient for e.g. In many cases an active

substance (such as aspirin) is not absorbed easily by human body in such cases the active ingredient is dissolved in or mixed with an excipient which may either act as solvent or assist in absorption of the drug in human body. Enhance overall safety and effectiveness of the formulation during its storage and use. These components are generally termed as excipients and according to the international pharmaceutical excipient council, Excipient is defined as "Any substance other than active drug or pro-drug that is included in the manufacturing process or is contained in finished pharmaceutical dosage forms". The US pharmacopoeia-National formulary (USPNF) categorizes excipients according to the functions they perform in the formulations e.g. Binders, disintegrants etc. Excipients can be classified on the basis of their origin, use in dosage form, and functions they perform as follows

1. Excipient based on their origin5 Animal source: - Lactose, Gelatin, Stearic acid, Bees

wax, Honey, Musk, Lanolin etc.

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Vegetable source: - Starch, Peppermint, Turmeric,

characteristics, segmental absorption behavior,

Guar gum, Arginates, Acacia etc.

drug delivery platform, intellectual property

issues etc while selecting an excipient for

Mineral source: - Calcium phosphate, Silica, Talc,

formulation development, this may help in

Calamine, Asbestos, Kaolin, Paraffin, etc.

determining the absorption challenges and desired

Synthetic: - Boric acid, Saccharin, Lactic acid,

delivery platform for active pharmaceutical

Polyethylene glycols, Polysorbates, Povidone etc.

ingredients.

The concept of quality by design (QbD) helps in

2. The following tables gives a classification of

understanding excipients normal variability and

various excipients used in pharmaceutical dosage

its potential impact on the processes of

forms: (table no 1,2,3)

formulation development can be achieved.

Excipient compatibility tests allows us to

3. Classification of excipients based on their functions 10-13:-

determine drug excipient interactions which can be either avoided or can be modified to utilize in

Excipients are classified on the basis of the functions

an efficient manner which helps in minimizing the

they perform such as:-

risk associated with the excipients. Excipient

Various excipients used in solid dosage forms

selection also depends on various routes of

perform various functions like:-

administrations. Excipient selection must be done

Binders, diluents, lubricants, disintegrating agent's

on the basis of characteristics an excipient offers.

plasticizers etc, e.g.: when 5% starch is used in

formulation it acts as a binder for tablet

The ideal characteristics of an excipient are given as

formulations where as when it is used in dry form

under:-

it can perform the function of a disintegrant.

An excipient must be:-

Excipients that are used in liquid dosage forms are:-

Chemically stable

Solvents co- solvents, buffers anti-microbial agents

emulsifying agents sweetening agents, flavors, etc

Some excipients have therapeutic values which are

classified as under:Anesthetics 10:- chloroform, etc Laxatives: - bentonite, psyllium, xanthan gum11,

guar- gum etc.

Ph modifiers: - citric acid.

Astringent: - cinnamon, alum, zinc sulphate. Carminative: - cinnamon13, dill water, anise water. Nutrient sources: - agar12, lactose, etc.

Non reactive Low equipment and process sensitive Inert to human body Non toxic Acceptable with regards to organoleptic

characteristics Economical Having efficiency in regards with the intended use. Excipients even though considered inert substance,

have the tendency to react with drug components, other excipients, and also the packaging system.

Excipient selection 14:Excipients can be considered as indispensible

component of medicinal products and in most of the formulations they are present in greater proportion with regards to active pharmaceutical ingredient, as it forms the bulk of the formulation it is always necessary to select an excipient which satisfies the ideal properties for a particular excipient. Excipient selection generally focuses

Excipients may also contain various impurities which may result in decomposition of the active pharmaceutical ingredients in the formulation thus altering the shelf life of the formulation. The various type of interactions that an excipient can undergo are termed as Drug-Excipient interactions Excipient-Excipient interactions Package-Excipient interactions

on the desirable characteristics of excipients such as functionality, material consistency, regulatory acceptance, cost, availability, and sources. Material properties like micromeritics, chemical thermal rheological, mechanical etc also play an important role in development of drug formulation. Formulators must also consider physicochemical properties, stability and compatibility issue,

These interactions are discussed in detail as follows: Drug ? Excipient interaction15-19

In pharmaceutical dosage forms the active pharmaceutical ingredients are in intimate contact with the excipients which are in greater quantity. Excipients and drugs may have certain incompatibilities which lead to drug ?excipient interaction.

pharmacokinetic attributes, permeation

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Excipients affect the physicochemical characters of the active pharmaceutical ingredient which may lead to formation of molecular complexes, increase in rate of chemical degradation etc.

Drug excipient interactions are further classified as Physical interactions Chemical interactions Biopharmaceutical interactions

a. Physical interactions: - physical interactions alter the rate of dissolution, dosage uniformity, etc. physical interactions do not involve chemical changes thus permitting the components in the formulation to retain their molecular structure. Physical interactions are difficult to detect. Physical interactions can be either beneficial or detrimental to the product performance which is dependent on its application.

Various types of physical interactions are listed as in table no 4. b. Chemical interactions: - active

pharmaceutical ingredients and excipients react with each other to form unstable compounds. Several chemical drugs ?excipient interactions have been reported in literature. Generally chemical interactions have a deleterious effect on the formulation hence such kind of interactions must be usually avoided, various examples of chemical interactions have been listed in table no 5. c. Biopharmaceutical interactions: - these are the interactions which are observed after administration of the medication. Interaction within the body is between medicine and body fluids which influence the rate of absorption. All excipients interacts in physiological way when they are administered along with active pharmaceutical ingredients, various examples of biopharmaceutical interactions are stated as follows:-

1) Premature breakdown of enteric coat:the enteric coating polymers like cellulose acetate phthalate and hydroxyl propyl cellulose acetate phthalate, are soluble more at basic pH, but antacids

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raise pH of stomach resulting in breakdown of the enteric coat in stomach and release of active pharmaceutical ingredient in stomach itself, which results in degradation of drug in stomach. In case of NSAID's premature breakdown of enteric coat may cause side effects like gastric bleeding.

2) Interactions due to adjunct therapy: Tetracycline antibiotics form complexes with calcium and magnesium ions which are quite common excipients in various formulations which may be administered along with tetracycline as adjunct therapy the complex so formed is not absorbed from the G.I.T.

3) Increase in gastrointestinal motility: many of the excipients like sorbital, xylitol, have tendency to increase the gastrointestinal motility thus reducing the time available for absorption of drugs like metoprolol. Polyethylene glycol 400 also has influence on the absorption of Ranitidine.

d. Excipient ?Excipient interactions [19, 20, 21, 22, 23, 24, 25, and 26]:- Excipient-Excipient interactions though observed very rarely, these are of prime importance in determining the stability of the dosage forms. Excipient ?Excipient interactions can be undesirable as well as some interactions are used in the formulations to get the desired product attributes. Various excipients undergo such kind of interactions.

Examples of undesirable Excipient-Excipient interactions are listed in table 6 15.

Some excipients are formulated as mixture in order to obtain desired effect in the product; such Excipient- Excipient interactions are beneficial for improving functional performances in the formulation. Such type of excipients can be considered as coprocessed excipients.

Co processed excipients: - Tablets are generally considered as a dosage form of choice when oral route is preferred, because of accurate dosing, better patient compliance. Excipients such as binders, disintegrants, diluents, glidants, lubricants



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etc are used along with the active

are very friable, co processing of

pharmaceutical ingredient in the tablet

mannitol with some polyols offer similar

manufacturing, These excipient offer in

flowability and compressibility with

enhancing various properties like

addition of low friability as compared to

dissolution, absorption etc of active

direct compressed mannitol.

pharmaceutical ingredient when in tablet.

Some excipients fail to give the desired

f. Added

functionality

partially

output; hence the need for modified

pregelatinized starches:- partially

excipients with enhanced properties is

pregelatinized starches are used as filers

developed.

in hard gelatin capsules (5-75%) binders

Co processing is a novel concept that has been

in wet granulation tabletting (5-20%),

introduced, which alters excipient

disintegrants in tablet formulation( 5-

functionality by retaining favorable

10%) and also in direct compression

attributes and supplementing with newer

tablets which also provide better particle

ones, by processing parent excipient with

size control, decreased friability, narrow

another excipient. The high functionality

particle size distribution, and reduced

excipients so formed help improve process

levels of fines. Partially pregelatinized

ability such as flow properties,

starch particles having compact,

compressibility, and improved disintegration

embedded matrix are significantly less

and dissolution profiles.

friable than those made of loosely

Introduction of high speed tablet machines and

associated ones. Such type of compact

direct compression techniques pose several

matrix partially pregelatinized starches

problems with the tablet manufacturing. Co

help in rapid dissolution of drugs e.g.

processed excipients aid in solving such

acetaminophen.

problems with their multifunctional

properties. Co processing provides a synergy

Some examples of such excipients are given

of functionality improvement, as well as

in table no 7

masking the undesirable properties of individual excipients. Co processing is

g. Package ?Excipient interactions28-31]:-

aimed at improving flow properties,

Packaging of pharmaceuticals is a vital

compressibility, disintegration potential and

part of the processing steps of product

development of filler binder combination.

formulation, hence in pharmaceutical

Many bulk excipients that are used for

industry its essential that package

conventional tablets are unsuitable for orally

selected adequately preserves the

disintegrating tablets which necessities the

integrity of products, the selection of

use of specific excipients and technology to

package therefore begins with a

mask drugs unacceptable taste and improve

determination of products physical and

the orally disintegrating tablet properties.

chemical characteristics, its protective

The quick effect of dispersion is due to the

needs, and its marketing requirements.

excipients ability to absorb water quickly.

The package thus selected should be

Tablets rapid dispersion on surface of

inert in nature, should protect the product

tongue is also facilitated by use of

from external environmental conditions,

superdisintegrants like crosspovidone

etc.

sodium, starch glycolate, crosscarmellose.

Usually the packaging material used is

glass; plastic, metal, rubber closures etc,

e. Added functionality mannitol for orally

these containers and closures react to

disintegrating tablets: - directly

certain extent with the drug product as

compressible mannitol is generally used

well as with the excipient and give

because of its property to prepare robust

deleterious effects thus altering the

tablets, spray dried or directly

product stability. Such interactions

compressible mannitol are highly porous

generally cause loss of product quality.

and friable which upon compression fill

These interactions are listed in the

the interstitial spaces between larger

following table no 8:-

porous particles. The disadvantage of orally disintegrating tablets is that they

Standardization of excipients 32

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Excipient quality plays a vital role in assuring safety, quality and efficacy of dosage forms. Standardization of excipient usually assures the customers and manufacturers that the excipient quality will meet the international market, therefore the rules for regulation of bulk excipients are stringent and whenever a new excipient is to be introduced it is necessary for the applicant to submit safety and quality data and for an approved excipient the applicant has to provide literature reference data.

The various reasons for which excipients must be standardized are:-To assure the customer that the excipients used are safe and will not alter the formulation and cause undesirable effects. To assure the manufacture that he is using a standard quality material for formulating his dosage form and To reduce resources to host frequent customer audits and assure excipient GMP audit is conducted against appropriate GMP conformance expectations.

The standard chosen as framework for quality management system is ISO 9001. The Iso certification has the advantage of assuring the customers that excipient manufactueres quality management system has been verified independently.

GMPpractise for excipients assures product integrity, avoid product contamination etc.

IPEC is an international industry association which is formed with the main objective of development and harmonization of international excipient standard and development of newer excipients. It deals with three kinds of stakeholder groups viz; suppliers, users and regulatory authorities. It is necessary to obtain sufficient data about the excipient and the manufacturer or distributer, usually to get such information and information of the excipient in detail the users and customers send questionnaires to the supplier, the questionnaire consists of large amount of queries which becomes very difficult to resolve and address every individual as lot of time and money is wasted during this process, hence in order to minimize this stressful process IPEC has put forward an standardized excipient package that comprises of Product regulatory database Site quality overview and Site and supply chain security overview.

This information is useful in responding to the questionnaires and other requests in a simplified

and standard process which is very effective in

saving time. This information helps both users

and suppliers to manage the information in a

systematic and efficient manner.

Product regulatory database: - this

document has been formed with the main

objective of providing information about

important

physical

properties,

manufacturing and regulatory information

specific to excipients to the user which

facilitates the use of excipients in drug

formulations. The various sections included

are

General product information:- this includes

information like product identification ,

product code/name, scope of document, and

any other information that is necessary,

Manufacturing, packaging, release and

supplier information:- this section

describes the information regarding

excipient manufacturing site and the

information related with it, for e.g.:-

manufacturing processing, packaging,

product release warehousing, laboratory site

etc, distribution channels, GMP or GDP

compliance statements, equipment

information etc.

Physicochemical information:- this section

deals with the information related to the

physical and chemical characteristics of the

product for e.g.:- CAS number, information

about the origin of excipients, their

synonyms, its morphological characteristics,

processes applied during manufacturing,

mixed excipient information and the country

of its origin if applicable.

Regulatory information:- this section

describes the regulatory status of an

excipient, it includes information like

compendia compliance (e.g. USP-NF, Food

chemicals codex, BP etc) drug master file,

or European Directorate for the Quality of

Medicines and healthcare (EDQM)

certificate of suitability, viral safety,

allergens, hypersensitivity information,

residual solvent information, metal catalyst

and metal reagent residue information.

Kosher/Halal status, bioburden/ pyrogen

(optional) information etc.

Miscellaneous product information:- this

section includes information like lot/batch

number, expiry date, use, nutritional

information (if applicable) packaging

information etc.

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