Diluents

Abdullah Al NomanDaffodil International University

Diluents

Diluents are fillers used to increase the bulk volume of a tablet diluent active pharmaceutical ingredients product adequate weight and size.

Diluent is a liquid used in coatings to dilute so that it can easily flow. It reduce the consistency of coating. The water used in latex coatings to thin it. In this case water is a diluent.

Diluent is also known as many terms such as:Reducers,Thinners,Reducing agents, orReducing solvents.

A diluent is a diluting agent to easily flow of solutions. It reduces viscosity of different mixers or solutions thereby it smoothly flow through holes or on the surface. It added in coatings or paints to ease the flow.

Common available diluent include:WaterPaint thinnerKerosene or dieselBenzene or phenol

Classification of diluentsThere are two types:

1) chemical nature

2) solubility

Difference Between a Solvent & Diluent?

Solvents may or may not make the chemical compound thinner and easier to use. Diluents are used for this purpose.

Conversely, diluents will not necessarily put a compound into solution. An appropriate solvent is needed for this purpose.

Purpose of diluents :

To enhance bulkiness To provide improved cohesion To enhance flow To allow direct compression manufacturing

Properties of diluents:

InertNontoxicBiocompatible Stable Acceptable Non-hygroscopic Commercially available in acceptable grades Colour-compatible No harmful effect on bioavailability of drugs.

Selection of diluents :

Compatibility FlowabilitySolubility Disintegration qualities Hygroscopicitylubricity Stability

Commonly used tablet diluents:

1. Lactose-anhydrous and spray dried lactose 2. Directly compressed starch-Sta Rx 1500 3. Hydrolyzed starch-Emdex and Celutab4. Microcrystalline cellulose-Avicel (PH 101and PH 102) 5. Dibasic calcium phosphate dehydrate 6. Calcium sulphate dihydrate7. Mannitol 8. Sorbitol 9. Sucrose- Sugartab, DiPac, Nutab10. Dextrose

Effects of diluents :

• Degradation of API (hydrolysis)• Mannitol - punch filming/ picking • Sucrose – tablet hardness-poor disintegration • Capping – low moisture • complex formation

How do you calculate dilution?To make a fixed amount of a dilute solution from a stock solution, you can use the formula :

C1V1 = C2V2

where:

V1 = Volume of stock solution needed to make the new solution.

C1 = Concentration of stock solution.

V2 = Final volume of new solution.

C2=?