This document discusses cosolvency as a technique for enhancing the solubility of poorly soluble drugs. It defines solubility and outlines reasons for enhancing solubility, such as improving oral bioavailability. It then describes cosolvency, where a cosolvent is added to increase the solubility of a drug by creating a solution with an enhanced solubility. Common cosolvents that are non-toxic, non-irritating, and able to cross membranes include glycerine, PEG, diethyl acetamide, and ethyl alcohol. Cosolvency works by creating a solution with dielectric properties between those of water and the original solvent. It is a widely used technique that allows for parenteral formulations and improves

1. School Of Pharmacy SRTMU Nanded
PRESENTED BY:
RAJESH LAXMAN RAUT
M.Pharm I (QA)
GUIDED BY:
Mr. G. CHATE SIR
Ast. PROFESSOR
CO-SOLVENCY

2. Content
 Introduction
 Solubility Definition
 Reasons For Solubility Enhancement
 Techniques for solubility enhancement
 Cosolvancy
 Mechanism of cosolvency
 Advantages and disadvantages

3. Introduction
 Solubility, the phenomenon of dissolution of solute
in solvent to give a homogeneous system, it is one of
the important parameter to achieve desired
concentration of drug in systemic circulation for
desired pharmacological response.
 Any drug to be absorbed must be present in the form
of solution at the site of absorption
 Therefore various technique are used for the
enhancement of the solubility of poorly soluble drugs

4. Solubility
 Definition:
The amount of substance that passes into the
solution in order to establish equilibrium at constant
temperature and pressure to produce a saturated
solution.

5. Need of solubility enhancement
 Oral administration of drug is the most commonly
used drug delivery route.
 The oral bioavailability is highly dependant on
solubility.
 Poorly water soluble drugs having slow drug
absorption leads to inadequate and variable
bioavailability.
 It will cause gastrointestinal mucosal toxicities.
 Therefore just to improve the bioavailability of a
drug one has to increase the solubility.

6. Solubility Enhancement Techniques
Techniques
Chemical
Modification
Change in pH
Physical
Modification
Miscellaneous
Modification
Cosolvent
Surfactant
Particle size
reduction

7. Cosolvancy
 The solubility of a poorly water soluble drug can be
increased by the addition of water miscible solvent in
which the drug has a good solubility
 This whole procedure is known as cosolvency and the
solvent is called cosolvant
 Cosolvents are mixture of water and one or more
water miscible solvent use to create a solution with
enhance solubility for a poorly water soluble drugs.

8. Characteristics of Cosolvents
• Non-toxic
• Non-Irritant
• Able to solubilise the Drug in Given Solvents
• Able to cross membrane
• Value of Dielectric Constant is In between 25-80

9. Widely used cosolvents
Glycerine
PEG
Diethyl Acetamide
Glycoferol
Ethyl Lactate
Ehyl Alcohol

12. Discussion
 Parenteral formulation may require addition of water or
a dilution step before administration.
 Dimethyl sulphoxide(DMSO) and Dimethyl
acetamide (DMA) have been widely used as cosolvents
b’coz of there large solubilisation capacity for poorly
soluble drug and there relatively low toxicities
 A blend of propylene glycol and water is use to improve
the solubility of clotrimoxazole in oral solution and
paracetamol is formulated as elixir by use of alcohol and
propylene glycol

16. 17/02/2017

17. 17/02/2017