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Glossary of terms

A

Acrylates

Co-polymers of methacrylic acid derivatives used in the pharmaceutical industry to effect modified release or taste masking. The popularity of acrylate polymers stems from their flexibility to produce desired release profiles and the fact that many of the polymers can be processed using aqueous systems. Acrylate polymers can be classified in terms of their solubility in acidic and neutral media, and this solubility determines their usual application. Enteric polymers are insoluble in acidic media and soluble in neutral media (types L and S), Extended release polymers are insoluble in both media (types NE, RL and RS) and taste masking polymers are soluble in acidic media but insoluble in neutral media (type E).

Amorphous lactose

Amorphous lactose is found mainly in two types of lactose. In typical spray dried lactose (SuperTab® 11SD) it is present at a level of about 10%, and it results from the rapid drying of the portion of dissolved lactose processed through the spray drier. In milled lactose the amorphous portion depends on the degree of milling, but as a guide a commonly used grade for wet granulation (say Pharmatose® 200M) contains about 2% amorphous lactose at the time of manufacture. Exposure of amorphous alpha-lactose to atmospheric moisture causes its recrystallisation to lactose monohydrate. 

Click here for the abstract: The effect of moisture content on the compression and bond formation properties of amorphous lactose: Sebhatu T, Ahlneck C and Alderborn G, Int J Pharm, (1997), 146, 101 - 114. Measurement of amorphous technical bulletin. 

Amylopectin

The major polysaccharide found in starches. Amylopectin consists of  chains of alpha-glucose linked 1 - 4 with branches (1 - 6 links) every 20 to 30 glucose units. Amylopectin is a very large molecule with MW of about 107 to 109 Daltons. Both corn starch and potato starch contain about 75% amylopectin and about 25%% amylose. 

Click here for the abstract: Starch—composition, fine structure and architecture: Richard F. Tester, John Karkalas, Xin Qi, Journal of Cereal Science 39 (2004) 151–165 

Amylose

The minor polysaccharide found in starches. Amylose differs from amylopectin in that it is largely unbranched 1 - 4 linked alpha-glucose and it has molecular weight of about 105 to 106 Daltons.

Click here for the abstract:  Starch—composition, fine structure and architecture: Richard F. Tester, John Karkalas, Xin Qi, Journal of Cereal Science 39 (2004) 151–165 

Abbreviated New Drug Application (ANDA)

An application to market a generic drug in the USA. The application does not contain extensive preclinical (pharmacology & toxicology) or clinical data. Instead an ANDA for a typical tablet or capsule relies on therapeutic equivalence to the innovator product (or reference listed product), together with an extensive CMC section.
Please click here to find more information on the FDA website.

Active Pharmaceutical Ingredient (API)

Drug substance.

Area Under the Curve (AUC)

The area under the curve of a plot of drug concentration in plasma against time. AUC has units of concentration * time (for example ng.h/ml). The AUC taken to infinity can be used to determine the bioavailability of a drug product.

B

Bioavailability (BA)

A measure of the fraction of a drug that enters the systemic blood circulation after oral administration. The usual measure is the ratio of the AUC of two different formulations of the same drug, corrected for dose. If an intravenous injection of 1 mg of a drug gives an AUC of, say, 1000 ng.h/ml, and a 5mg tablet gives an AUC of, say, 3000 ng.h/ml, then the oral bioavailability of the tablet is said to be 60% (=3000/5*1/1000*100) of the injection.

Bioequivalence (BE)

Two drug products are considered bioequivalent if they exhibit the "same" Cmax, Tmax and AUC in a properly powered pharmacokinetic study. In other words the two drug products have the plot of "drug concentration in plasma" against "time". The actual definition of "same" when applied to the pharmacokinetic parameters varies from country to country. If two drug products are bioequivalent then it is assumed that they are therapeutically equivalent. A bioequivalence study is the cornerstone of an ANDA or any OSDF generic drug application, because for the reasons given here, bioequivalence obviates the need to perform long & expensive clinical studies.

Binding

Difficulty in ejection of tablets from a die after compression. Binding is evident as excessive ejection force, and it can sometimes be heard as a "sqeaking" noise during tableting. In extreme cases binding can result in tablet lamination. Increase in the amount of lubricant (magnesium stearate or talc) is a potential solution, as is proper maintenence and polishing of the dies. If this is not feasible then coated or tapered dies are available that can reduce the friction during ejection.

Biopharmaceutical Classification System (BCS)

A system of classification of drugs based on their solubility and their permeability through the gut wall. The system was introduced by Professor Gordon Amidon in 1995. A soluble drug is one whose highest dose is soluble in 250ml or less of aqueous media over the pH range 1 to 7,5. A permeable drug is one that is more than 90% absorbed from the human gut. Permeability may be determined using in vitro model systems. The BCS classes are Class 1: high solubility & high permeability. Class 2 = low solubility & high permeability. Class 3 = High solubility & low permeability. Class 4 = low solubility & low permeability. 

Please click here for the abstract: A Theoretical Basis For a Biopharmaceutic Drug Classification: The Correlation of In Vitro Drug Product Dissolution and In Vivo Bioavailability: Amidon, G. L., Lennernas, H., Shah, V. P., and Crison, J. R.:  Pharm. Res., (1995) 12: pp 413-420. 

Biowaiver

An exemption from the need to perform a clinical bioequivalence study under certain circumstances. Biowaivers are possible in the USA, in Europe and in Japan, but the requirements for achieving a biowaiver differ in these countries. In the USA and Europe the biowaiver is potentially available for rapidly dissolving formulations of BCS class 1 drugs.

Please click here for more information from the FDA website.

Please click here for more information about EMEA guidelines.

Please click here for more information.

Bradford's method

A method for estimating the amount of protein or protein residues in a sample of, for example, lactose. The method depends on the shift in the absorbance of an acidic solution of Coomassie Brilliant Blue G from 465nm to 595nm upon complexation with proteins. The method gives a very much lower estimate of protein than Kjeldahl's method, which is also commonly used. The amount of protein in pharmaceutical lactose measured by Bradford's method tends to be less than 50ppm.

C

Capping

A fault in tablet making. In capping the top of the tablet separates from the rest of the tablet. Capping may be apparent as the tablet is ejected from the die, or occur at some subsequent stage in tablet processing, for example during coating or friability testing, or at any other time when the tablet is stressed. Capping is usually explained in terms of air entrapment in a tablet or in terms or stress relaxation during decompression. The cures include increasing the compression dwell time (slowing the machine or adding precompression), decreasing the compaction force applied or increasing the binding within the tablet.

Certificate of Analysis (CoA)

A batch specific set of tests and test results showing that a batch of material complies with its specification.

Certificate of Standards (CoS)

The general specification to which a pharmaceutical product or excipient will be release. It differs from a Certificate of Analysis in that batch specific results are not presented.

Chemistry, Manufacturing and Controls (CMC)

The section of an ANDA or NDA where all the data on synthetic chemistry, impurities, formulation, manufacturing, packaging, specifications, analytical methods and stability are submitted.

Closed Joined Length (CJL)

The length of a hard gelatin capsule after it has been filled and completely closed by a capsule filling machine. Most capsules have a lock that makes than difficult to open after they have been closed to this length.

Coating

The process of applying a coat to a tablet or other dosage form. Coatings are applied for a number of reasons from aesthetic (colour, identification and ease of handling or swallowing) to highly functional (delayed and modified release). Aesthetic coatings are typically based on low viscosity grades of HPMC or PVA, whereas functional coatings are typically based on methacrylic acid copolymers or cellulose derivatives such as ethylcellulose.

Colony Forming Unit (CFU)

A measure of the number of viable micro-organisms present in a given weight or volume of sample, based on the principle that a single organism can grow and form a visible colony on a suitable plate.

Common Technical Document (CTD)

A harmonised layout for the structure and content of application dossiers applicable to the USA, the European Union and Japan. The CTD has 5 modules of which module 3 (Quality) contains the chemical and pharmaceutical section of the dossier.

Click here for more information.

Compression mix

The powder processed into tablets on a tablet machine. A compression mix may be made by wet granulation, dry granulation, simple blending or any other suitable technique.

Controlled Release (CR)

An out of date synonym for extended release.

Croscarmellose sodium (CCS)

Cross-linked carboxymethyl cellulose used as a superdisintegrant in tablets and other oral solid dosage forms.

Please click here for more information about DFE Pharma CCS.

D

Delayed Release (DR)

A drug product (typically oral) that is not intended to release the drug substance immediately after ingestion. The delay is commonly related to change of pH in the gastrointestinal tract ("enteric coating") or less commonly may relate to a specific time after ingestion when the drug is released. Enteric coating is achieved by coating with polymers that are poorly soluble in low pH media (for example gastric fluid), but are soluble in media with pH values typically found lower in the intestine. Methacrylic acid copolymers are very commonly used for delayed release coatings as they can be supplied in grades that dissolve at different pH values.

Dibasic calcium phosphate (DCP)

A commonly used diluent or filler-binder for tablets. There are two overall types of DCP, namely the anhydrous form and the dihydrate form. The dihydrate form tends to lose its two molecules of water of crystallisation at elevated temperatures and revert to the anhydrous form. This happens even under accelerated stability conditions of 40 degrees C and 75% relative humidity.

Diluent

A component of a tablet or capsule, usually present to add bulk to the dosage form. The most commonly used diluents include lactose, microcrystalline cellulose and native or pregelatinised starches. Dibasic calcium phosphate and mannitol are also used.

Direct Compression (DC)

A means of producing a tablet without granulation. The active ingredient is blended with excipients, typically at least a filler-binder, a disintegrant and a lubricant and then the blend is compressed on a tablet machine. The filler-binders are usually special grades of excipients (for example spray dried lactose) exhibiting good flow and compaction properties to enable the DC process.

Disintegrant

An excipient that facilitates the disintegration of a tablet or other dosage form in contact with water or gastro-intestinal fluid. Traditionally starch was used, but in general today's formulations utilise a so called superdisintegrant such as croscarmellose sodium or sodium starch glycolate. Superdisintegrants are typically cross-linked hydrophilic polymers that strongly attract water. The presence of the cross links allows swelling, but prevents dissolution of the polymer and generation of high viscosity gels.

Please click here to learn more about DFE Pharma disintegrants.

Disintegration

The process by which a solid oral dosage form breaks up in water when measured in a standard apparatus. The test is not harmonised. In the USP-NF requirements for disintegration time are given in each particular monograph. In the Ph. Eur. the requirements are in the general chapters on dosage forms These requirements (for example 15 minutes for uncoated tablets, 30 minutes for film coated tablets and hard gelatin capsules, 60 minutes for other coated tablets) are generally easily met with the use of superdisintegrants.

Dissolution

The process by which drug dissolves out of a dosage form and is made available for absorption from the gastro-intestinal tract. In vitro measurements are made in a range of apparatus types. The requirements for different types of dosage forms are given in each pharmacopoeia.

Drug

Typically used to mean drug substance (ie the active ingredient or API). But in the FDA terminology "drug" can mean either drug substance or drug product (ie tablet, capsule etc.).

Drug Master File (DMF)

A DMF is a means of providing data on a processing facility, drug substance, packaging material or excipient confidentially to FDA. The data in a DMF can be accessed by FDA in support of an NDA upon provision of a letter of access (a letter from the DMF holder to the NDA applicant authorising FDA to access the DMF during their review of a particular NDA). In Europe there is no DMF system for excipients and in Japan there is a recently introduced system.

Dry Granulation (DG)

A means of granulation (size enlargement) of a powder using a compaction step followed by milling. The most common means of dry granulation in pharmaceutical industry is roller compaction, although the older process of slugging is still sometimes used. Anhydrous lactose is the most suitable form of lactose for these processes because it tends to retain compactability after the dry granulation process.

Please click here for more information about dry granulation.

Dry Powder Inhaler (DPI)

A dosage form for delivery of drug to the airways consisting of a micronised respirable drug, usually dispersed on lactose as a carrier and packaged into a single dose or multiple dose device. All DPIs are actuated by the patient on breathing and are therefore very patient friendly.

Please click here for more information about inhalation.

E

Endotoxin

A term for lipopolysaccharides deriving from the cell wall of gram negative bacteria. For excipients to be used in inhalation or injectable dosage forms it is important to control the level of endotoxin to a low level of typically not more than 5 EU per gram.

Enteric coat

A delayed release coating, usually designed to delay release of the drug from the dosage form until it has reached an area of the gastro-intestinal tract of a specified pH. Methacrylic acid copolymers are very commonly used.

Excipient

A component of a drug product other than the API, that is intentionally added to the dosage form to enable processing into patient friendly medicines, to control the rate at which the API dissolves from the dosage form, to aid drug stability and other reasons. For solid oral dosage forms, main classes of excipients include diluents or filler-binders, disintegrants, glidants, lubricants, coating materials, and stabilising agents.

Extended Release

A form of modified release dosage form in which the dissolution rate of the drug from a medicine is controlled over an extended period of time, usually to reduce the frequency at which a patient has to take the medicine. A number of means of effecting extended release are possible, the most common being barrier coating (with for example acrylate polymers), inclusion of hydrogel polymers (for example hydroxypropyl methyl cellulose) and construction of osmotic pumps. Older synonymous terms are slow release and controlled release.

F

FDA Form 483 (483)

A form of observations usually produced after an FDA inspection of a drug development or drug manufacturing facility. Only significant deviations from cGMP are listed and thus 483 observations are only negative.

Please click here for more information on the FDA website.

Filler-binder

A term sometimes used to describe a direct compression excipient. A filler binder is a compressible carrier that provides the dual function of good flow and good compaction properties thus enabling the DC process. The most commonly used filler binders are microcrystalline cellulose and some forms of lactose (spray-dried, granulated and anhydrous). Other filler-binders are some types of mannitol, dibasic calcium phosphate. Filler binders are often used in combination to optimise DC tablet properties.

Please click here to find the most suitable filler-binder for your application.

Food and Drug Administration (FDA)

The US FDA is responsible for protecting public health by assuring the safety, efficacy and security of, amongst other things, human drugs.

Please click here to access the FDA website.

Friability

A measure of the resistance to abrasion and breakage of tablets during a standardised test involving tumbling tablets in a rotating drum. Details of the equipment and test protocol are found in all main pharmacopoeia. A limit of not more than 1% weight loss is generally taken to be a satisfactory measure of friability.

Please click here for more information about EMEA guidelines.

G

Generic drug

A drug for which the patents protecting the originator product have expired (or may be challenged). Generic products are pharmaceutically equivalent to a reference listed drug (same drug substance, same route of administration, same dosage form and same strengths) and are also therapeutically equivalent (typically bioequivalent for oral solid dosage forms).

Please click here for more information on the FDA website.

H

Hard gelatin capsule

Hard two piece gelatin capsules are the second common oral solid dosage forms after compressed tablets. They are relatively easy to formulate. Hard gelatin capsules are used in certain dry powder inhaler devices. Hard capsule shells made from HPMC have advantages in inhalation formulations.

Hydrofluoroalkane (HFA)

Propellants used in current pressurised metered dose inhalers (pMDI) are HFAs. They replaced the ozone depleting chlorofluorocarbons. The two propellants used in MDI formulations are HFA 134a (1,1,1,2-tetrafluoroethane) and less commonly HFA 227 (1,1,1,2,3,3,3-heptafluoropropane).

I

Investigational New Drug (IND)

The permission to ship an experimental drug across state lines in the USA in order to conduct clinical trials.

Please click here for more information on the FDA website.

In-vitro In-vivo correlation (IVIVC)

A mathematical means of establishing the relationship between in-vitro dissolution data of a dosage form and an in-vivo response elicited by that dosage form, such as plasma level of drug or a derived drug absorption profile. A strong IVIVC can in some circumstances support a biowaiver.

Please click here for more information from the FDA website.

K

Kjeldahl's method

A means of estimating the amount of protein in an sample. Kjeldahl's method in fact measures total nitrogen in a sample and this is multiplied by a factor of 6,4 (for proteins in lactose). Kjeldahl's method therefore overestimates the amount of protein in lactose because of its indiscriminate measurement of total nitrogen, and when measured by this method lactose typically gives values below about 350ppm.

L

Lactose

A disaccharide commonly used in pharmaceutical tablets & capsules as a diluent or filler-binder, and extensively used in dry powder inhalers as a carrier.

Please click here for more information about lactose.

Lactose intolerance

The normal reduction in lactase activity in mature mammals that results in lactose not being cleaved into glucose and galactose in the gastro-intestinal tract. Cleavage is necessary for absorption because lactose itself is not absorbed, and passes into the large intestine where it causes symptoms of bloating. The amount of lactose necessary to cause symptoms is variable but is generally assessed to be 10g or more.

Please click here to access the abstract: Lactose Intolerance: DL Swagerty Jr., M.D., M.P.H., AD. Walling, M.D., and RM Klein, Ph.D.  American Family Physician, Vol 65 No. 9, May 1st 2002,

Lamination

The presence of weak planes in a compressed tablet normal to the direction of compaction. On subsequent handling or processing it is possible for the tablet to separate into layers along these weak planes. Lamination may have the same causes as capping, or it may also be a result of under lubrication of the tablet compression mix.

Lubricant

An excipient that is used in tablet and capsule formulations to allow ejection of the compressed tablet from the die, or the capsule plug from the dosator. Lubricants also act as anti-adherents to prevent sticking of the tablet to the tablet punches during compression. By far the most commonly used lubricant is magnesium stearate, although less hydrophobic materials such as sodium stearyl fumarate are now available. Other lubricants include calcium stearate and mixtures of talc and stearic acid. Options to minimise the need for tablet lubrication include the use of coated punches in compression and tablet machine developments that add very small quantities of lubricants directly to the punches during tableting.

M

Magnesium stearate

Easily the most common tablet lubricant, magnesium stearate is used in the vast majority of tablet and capsule formulations. It is commonly used at levels of about 0.5% of the tablet formulation and can cause unwanted effects such as reducing tablet strength on compaction and prolonging tablet disintegration and dissolution of the API. Some excipients are more prone to the effects of magnesium stearate than others. One potential solution to these adverse effects is to incorporate colloidal silicon dioxide into a formulation.

Maillard's reaction

A browning reaction that occurs between reducing sugars and amines.

Mannitol

A sugar alcohol used as a tablet diluent or filler binder. Mannitol is commonly used in the formulation of chewable or orally dispersible tablets where it imparts a good "mouthfeel" to the products.

Modified release (MR)

A Modified Release tablet is one  that is not immediate release. That is, it is not intended to release its drug payload immediately and rapidly after ingestion. There are two subclasses of MR namely DR (delayed release) and ER (extended release).

N

New Drug Application (NDA)

The process by which a pharmaceutical company requests permission to manufacture and sell a new drug in the USA. The NDA differs from the ANDA in that it contains extensive data on safety and efficacy of the proposed new drug.

Please click here for more information on the FDA website.

O

Orally disintegrating tablet

An ODT is a dosage form designed to disintegrate or dissolve quickly in the mouth without the need for water and without chewing. In general the tablet should disintegrate within 30 seconds when tested using standard pharmacopoeial disintegration apparatus, or another correlated disintegration test method.

Please click here for more information from the FDA website.

P

Paragraph 4 filing

A type of ANDA submitted during the patent term of the originator product. The filing asserts that either the patents supporting the originator product are invalid or that they are not applicable to the product that is the subject of the ANDA.

Pellicle

In a hard gelatin capsule, a pellicle is an insoluble mass of gelatin formed on storage and usually attributed to the formation of gelatin cross links. Excipients may contribute to the formation of pellicles if they contain impurities liable to cross link gelatin (for example low molecular weight aldehydes). Pellicles can impede drug dissolution, in which case it is permissible to perform the dissolution test in the presence of enzymes.

Please click here for more information on the FDA website.

Pharmacokinetics (PK)

The study of the time course of the way the body handles drugs. There are four essential processes following a persons ingestion of a tablet or other oral dosage form, collectively known as ADME processes (Absorption of the drug from the gut; Distribution of the drug into other body tissues; Metabolism of the drug to other chemicals (metabolites) and Elimination of the drug from the body). This time course is typically followed by taking blood samples from volunteers at time intervals following swallowing a tablet, and measuring the amount of drug and / or metabolites in the plasma. A plot can be constructed of plasma concentration against time from which various PK parameters such as Cmax, Tmax and AUC can be derived. Other fluids may be analysed, for example urine.

Picking

Picking is very akin to sticking, although it is also used to refer to sticking that occurs specifically in the debossed part of a tablet. Remedies are the same as for sticking, and additionally simplification of the punch design may help.

Pregelatinised Starch (PGS)

Starch that has been wholly or partly pregelatinised by the application of heat and / or pressure. Starch may be partly pregelatinised or fully pregelatinised. Partly pregelatinised starch is used as a multifunctional component of tablets, and fully pregelatinised starch is most commonly used as a tablet binder in wet granulation.

Please click here for more information about DFE Pharma PGS.

Pressurised Metered Dose Inhaler (pMDI)

Sometimes just called an MDI. An MDI is a device containing micronised drug, propellants (HFAs) and sometimes other excipients designed to administer drug locally to the lung. Actuation of the MDI releases a metered dose of drug in propellant for the patients inhalation.

Q

Quality by Design (QbD)

Defined as "A systematic approach to development that begins with predefined objectives and emphasizes product and process understanding and process control, based on sound science and quality risk management."in ICH Q8 guideline.

Please click here for more information about the EMEA guidelines.

Please click here for more information about QbD guidelines.

R

Reference Listed Drug (RLD)

The listed drug identified by FDA as the drug product upon which an applicant relies in seeking approval of its ANDA. A generic drug must exhibit therapeutic equivalence to the RLD.

Please click here for more information on the FDA website.

Roller compaction

A dry granulation process in which a powder blend is passed through rollers under pressure to form a ribbon. The ribbon is milled into granules, optionally blended with extragranular excipients and recompressed into tablets or filled into capsules.

Please click here for more information about dry granulation.

S

Slow Release

An older and now outdated term for extended release.

Slugging

A form of dry granulation, somewhat similar to roller compaction. In slugging however a powder blend is first compressed on a tablet machine and the resulting, usually large, tablets (slugs) are milled, optionally reblended with more excipients, and recompressed into tablets. Alternatively the milled slugs are sometimes filled into capsules.

Please click here to find more information about dry granulation.

Sodium Starch Glycolate (SSG)

Cross linked carboxymethyl potato starch, commonly used as a disintegrant for tablets and capsules.

Please click here for more information about DFE Pharma SSG.

Soft (Elastic) Gelatin Capsule (SEG)

A dosage form consisting of a liquid fill encapsulated in a plasticised gelatin shell. Unlike hard gelatin capsules, the entire dosage form is formed in a single operation in which the capsule walls are formed from two gelatin ribbons at the same time as the fill is introduced between the ribbons.

Starch

A diluent and disintegrant for tablet and capsule formulations. Native starch does not have the compactability necessary to form coherent tablets. Maize and corn starches are the most commonly used native starches.

Please click here to learn more about DFE Pharma starches.

Sticking

Adhesion of a powder to the faces of a punch during tablet compaction. Causes are various and include low melting components in a compression mix, inadequate drying of a granulation, and inadequate lubrication of the compression mix. Additionally poor punch maintenance can contribute to sticking. The remedies are generally evident from the causes, but if low melting components cannot be excluded from a formulation then specially coated tablet punches may be a solution. Occasionally changes to the punch design (for example reducing the depth of concavity) may alleviate the problem.

SUPAC-IR

Scale Up and Post Approval Changes for Immediate Release Dosage Forms. A guidance document issued by FDA describes the regulatory steps and documents needed for making changes to the formulation, scale and site of manufacture of immediate release dosage forms. A similar guidance document has been issued in the European Community describing variations to marketing authorisations. Please click here for more information from the FDA website.

Please click here for more information on EMEA guidelines.

SUPAC-MR

Scale Up and Post Approval Changes for Immediate Release Dosage Forms. A guidance document issued by FDA describes the regulatory steps and documents needed for making changes to the formulation, scale and site of manufacture of modified release dosage forms.

Please click here for more information from the FDA website.

T

Tablet

A convenient dosage form in which API and excipients are compressed into tablets containing an individual dose of the API. Tablets can be formulated in a variety of types to provide immediate release or modified release of the API, or to make tablets that disintegrate readily in the mouth of a patient without the need to take the tablet with water.

Tablet Breaking Force

The force required to break a tablet in a plane when a compressive load is applied. The USP-NF (chapter 1217) recommends use of the term tablet breaking force instead of "hardness" or "crushing strength".

Talc

A commonly used excipient, talc is used as a lubricant / antiadherent glidant during compaction, and also as an antiadherent component in some film coat formulations.

U

Uniformity of dosage units

A measure of the degree of uniformity of the amount of active substance in individual dosage units (for example individual tablets or capsules). For uncoated tablets, film coated tablets and hard capsules containing  at least 25mg of drug substance and the drug substance is at least 25% of the dosage form, then variation in weight may be used as a measure of uniformity. For other solid oral dosage forms then individual unit assays are necessary. Specific details are given in major pharmacopoeia. A draft consensus guideline has been published.

Please click here for more information on the FDA website.

W

Wet Granulation

A means of granulation of powders using water or other liquid to agglomerate powders into granules, and drying the granules. The process fixes API and excipients into a granular form that helps to prevent segregation of the components, that aids flow of there powders, and allows the incorporation of binders to improve compactability. The granulation step and the drying step may be performed consecutively (typically using high shear granulation and fluid bed drying) or concurrently (typically using fluid bed granulation). Continuous wet granulation is increasingly being used to aid throughput in pharmaceutical processing factories.

Please click here for more information about wet granulation.