DILUENTS

Presented bySindhu Doppalapudi

PE/2011/306

INTRODUCTION

Definition : Diluents are inactive substances to

increase bulk and convert in the compressible form,

when drug material is potent or inadequate to

provide a suitable shape and size to tablet.

They are also known as fillers and the range of

diluent is 5% to 80%.

PROPERTIES OF DILUENTS

1. They must be non-toxic

2. They must be commercially available in acceptable

grade.

3. Their cost must be low.

4. They must be physiologically inert.

5. They must be physically and chemically stable by

themselves and with drugs.

6. They must be free from microbial contamination.

7. They do not alter the bioavailability of the drug.

8. They must be color compatible.

These are the various properties that an ideal

diluent must possess.

COMMONLY USED DILUENTS

Lactose anhydrous and spray dried lactose

Directly compressible starch-sta Rx 1500

Hydrolysed starch-emdex and celutab

Microcrystalline cellulose –Avicel (PH 101 and PH

102).

Dibasic calcium phosphate dihydrate

Calcium sulphate dihydrate

Mannitol

Sorbitol

Calcium carbonate

Dextrose

Sucrose- sugartab

dipac

nutab

CLASSIFICATION

Two ways to classify diluents

1. Based on type of material

2. Based on solubility

BASED ON TYPE OF MATERIAL

TYPE EXAMPLES

organic sugars , starches, celluloses

Inorganic Calcium phosphates

Co-processed Fast flo lactose, dipac, sugartab, nutab

BASED ON SOLUBILITY

INSOLUBLE TABLET FILLERS OR DILUENTS

SOLUBLE TABLET FILLERS ORDILUENTS

Starch

Powdered cellulose

Microcrystalline cellulose

Calcium phosphates, etc.

Lactose

Sucrose

Mannitol

Sorbitol, etc.

NAME OF THE DILUENT CHARACTERISTICS

Alpha-lactose monohydrate (pharmatose, respitose )

Used in wet granulation

Responsible for maillard reactionSpray dried lactose(spray process 315)

Directly compressible diluent, compressibility adversely affected if dried below 3% moisture

Darkening in presence of amines due to furaldehyde

Anhydrous lactose(pharmatose DCL 21)

Directly compressible

Pick up moisture at elevated humidity

Pregelatinised starch(starch 1500 LM)

Directly compressible

Good binding and disintegrant properties

Sucrose Requires high machine pressures

Good binding property and hygroscopic

Mannitol(parteck M/pearlitol/mannogem)

Widely used in chewable tablets

Non-hygroscopic

Sorbitol(sorbifin/neosorb) Highly compressible diluent

Hygroscopic in nature

MCC Most widely used directly compressible tablet diluent.

Plastic deformation on compression.

Calcium phosphates Directly compressible, produce hard tablets and abrasive in nature.

Alkalinity is the major source of instability.

NOTE ON DIRECTLY COMPRESSIBLE DILUENTS

Selection of direct compression diluent is extremely

critical, because the success or failure of direct

compression formulation completely depends on

characteristics of diluents.

There are number of factors playing key role in

selection of optimum diluent.

Factors like- Primary properties of API (particle size

and shape, bulk density, solubility).

The characteristics needed for processing

(flowability, compressibity).

Factors affecting stability (moisture, light, and other

environmental factors).

Economical approach and availability of material.

REFERENCES

Raymond c rowe, Paul j sherkey, Sian c owen: hand book of pharmaceutical excipients, 5th edition.

http://www.pharmainfo.net/tablet-ruling-dosage-form-years/formulation-tablets