Published on May 22, 2012
Practical physical pharmacy11: Practical physical pharmacy11 Exp. No.:5 Solubility enhancement by complexation March.2012 PowerPoint Presentation: Introduction The common methods used to enhance water solubility of a drug are: 1-solubilization by surfactants. 2-solvent combination. 3-salt formation. 4-Complexation. PowerPoint Presentation: nearly 40% of the new chemicals currently being discovered are poorly water soluble drugs. Question: Why is aqueous solubility considered as one of the rate limiting parameter for all drugs especially orally administered drugs ? Aqueous solubility of any therapeutically active substance is a key property as it governs dissolution, absorption and thus to achieve its desired concentration in systemic circulation to get the pharmacological response. Theory : PowerPoint Presentation: Orally administered drugs are absorbed only when they show good solubility in gastric medium and such drugs show good bioavailability. The solubility and dissolution properties of drugs play an important role in the process of formulation development . Insoluble drug can form a soluble complex with some compounds. e.g. Indomethacin + β - Cyclodextrin . e.g. Aspirin + Tri-sodium citrate. Theory : PowerPoint Presentation: Complexation is the association between two or more molecules to form a nonbonded entity with a well defined stoichiometry . Complexation relies on relatively weak forces such as London forces, hydrogen bonding and hydrophobic interactions . Complexation is by using a complexing agent. Theory : PowerPoint Presentation: Aim of Experiment: To Solubilize aspirin in water by complexation using tri-sodium citrate (TSC) as a complexing agent. ASPIRIN Formula: CH 3 COOC 6 H 4 COOH, MOL.WT.=180.16 PowerPoint Presentation: Complexing agent : Tri-Sodium Citrate . Formula: C6H5Na3O7･nH2O (n = 2 or 0) Description Tri-sodium Citrate occurs as colorless crystals or as a white powder ,it is odorless and has a cool, salty taste. Procedure:: Procedure: 1-into 6 clean dry conical flasks add 1 g. aspirin. 2-Add to these flasks 0,0.5,1,2,4 & 6 g. TSC respectively. 3-Add 50ml D.W to each flask. 4-Shake for 10min,filter,rinse the flask with the first portion of filtrate, complete filtration. 5-Take 10ml of filtrate from each flask& titrate with 0.1N NaOH using phenol red indicator. End point Yellow--------Pink. 6-Record the end point 7-Plot %Aspirin dissolved vs. g.TSC used. PowerPoint Presentation: ASPIRIN(Acetylsalicylic Acid) Aspirin has a long past. Salicin is the active ingredient from willow bark of Salix alba. Salicylic acid (1838) was used for pain relief and fever but its acidity was a major problem. PowerPoint Presentation: Aspirin was discovered by the Felix Hoffman & was first introduced into markets in 1899. It is prepared by the esterification of the phenolic hydroxyl group of salicylic acid. PowerPoint Presentation: Uses of Aspirin : Analgesic,antipyretic,anti-inflammatory, anti-platelet.. Side effects of Aspirin : Duodenal & peptic ulcer ,Reye’s Syndrome ,asthma.. PowerPoint Presentation: H.W.(A):Can aspirin be formulated using salt formation method? H.W.(B):Mention other methods used for solubility enhancement. H.W.(C):Write the difference between normal aspirin & buffered aspirin. H.W.(D):Write the synthesis of salicylic acid from phenol .