Physical Pharmacy Lab - Solubility of Drugs PDF

CYCLE SEM Physical Pharmacy LAB PHARM3A | TUTOR 1 1 MODULE 4: SOLUBILITY OF DRUGS PRE LABORATORY D...

CYCLE SEM Physical Pharmacy LAB PHARM3A | TUTOR 1 1 MODULE 4: SOLUBILITY OF DRUGS PRE LABORATORY DISCUSSION Solubility is also quantitatively expressed in terms of molality, molarity, and percentage. Solubility A saturated solution is one in which the solute in solution is in equilibrium with the solid Solubility is defined: phase. o in quantitative terms as the An unsaturated or subsaturated solution is concentration of solute in a saturated one containing the dissolved solute in a solution at a certain temperature, concentration below that necessary for o and in a qualitative way, it can be complete saturation at a definite temperature. defined as the spontaneous A supersaturated solution is one that interaction of two or more substances contains more of the dissolved solute than it to form a homogeneous molecular would normally contain at a definite dispersion. temperature, were the undissolved solute Solubility is an intrinsic material property that present. can be altered only by chemical modification Factors Affecting Solubility of the molecule. a. Particle Size (surface area) of drug particles Generally speaking, the solubility of a b. Molecular Size compound depends on the physical and c. Boiling Point of liquids and Melting Point of chemical properties of the solute and the solids solvent as well as on such factors as d. Temperature temperature, pressure, the pH of the solution, e. Crystal Properties and, to a lesser extent, the state of subdivision f. pH of the solute. Of the nine possible types of mixtures, based IDEAL SOLUTION NON IDEAL SOLUTION on the three states of matter, only liquids in A non ideal solution is a liquids and solids in liquids are of everyday An ideal solution is a solution that has importance to most pharmaceutical scientists solution where differences in the and will be considered in this module. interactions between interactions between molecules are identical molecules of difference Understanding the phenomenon of solubility helps between all the molecules components in the pharmacists to: in the solution. solution. 1. Select the best solvent for a drug or a mixture of Have identical have solvent-solvent, drugs, interactions between all solvent-solute, and 2. Overcome problems arising during preparation of the molecules solute-solute interactions pharmaceutical solutions, the change in enthalpy the change in enthalpy 3. Have information about the structure and when an ideal solution when a non ideal solution intermolecular forces of the drugs, forms is zero or forms is either a positive 4. Many drugs are formulated as solutions or added approximately zero or negative value as powder or solution to form liquids, concentrated solutions 5. Drugs with low aqueous solubility often present highly dilute solutions can heave as non ideal problems related to their formulation and behave as ideal solutions solution bioavailability. Expression of Solubility The United States Pharmacopeia (USP) describes the solubility of drugs as parts of solvent required for one part solute. AD | PHARMACY 2A | 2021 1  Parts of Solvent Description Form Solubility Range Solubility Assigned Required for One Part of (Solubility Definition) (mg/mL) (mg/mL) Solute Very soluble (VS) 1000 1000 Freely soluble (FS) 1 – 10 100 – 1000 100 Soluble 10 – 30 33 – 100 33 Sparingly soluble (SPS) 30 – 100 10 – 33 10 Slightly soluble (SS) 100 – 1000 1 – 10 1 Very slightly soluble (VSS) 1000 – 10 000 0.1 – 1 0.1 Practically insoluble (PI) > 10 000 < 0.1 0.01 POST LAB DISCUSSION A. SOLIDS DESCRIPTIVE TERM OF SOLUBILITY SUBSTANCES DISTILLED WATER ETHANOL CHLOROFORM ETHER ALUMINUM SULFATE FREELY SOLUBLE INSOLUBLE INSOLUBLE INSOLUBLE ASCORBIC ACID FREELY SOLUBLE SPARINGLY SOLUBLE INSOLUBLE INSOLUBLE CALCIUM STEARATE INSOLUBLE INSOLUBLE INSOLUBLE INSOLU B. LIQUIDS SAMPLES DESCRIPTIVE TERM OF SOLUBILITY BENZENE AND CHLOROFORM MISCIBLE WATER AND ALCOHOL MISCIBLE WATER AND PHENOL MISCIBLE WATER AND OIL IMMISCIBLE WATER AND PEPPERMINT OIL WITH PPG IMMISCIBLE WATER AND BENZYL BENZOATE WITH PPG IMMISCIBLE WATER AND ETHER WITH ACETONE MISCIBLE AD | PHARMACY 2A | 2021 2  MODULE 4: SOLUBILITY OF DRUGS A. EFFECTS OF TEMPERATURE TEST TUBE BEFORE HEATING AFTER HEATING REMARKS 1. CALCIUM HYDROXIDE + H2O SLIGHTLY SOLUBLE SOLUBLE + 2. HYDROUS SODIUM SULFATE + H2O SOLUBLE SOLUBLE + 3. SODIUM CHLORIDE + H20 SOLUBLE SOLUBLE + B. EFFECT OF OTHER SUBSTANCES BEFORE ADDING SECOND AFTER ADDING SECOND SAMPLE REMARKS SUBSTANCE SUBSTANCE SILVER NITRATE + SODIUM CHLORIDE (-) DOES NOT AFFECT COLORLESS SOLUTION SOLUTION (precipitation) SOLUBILITY (+) AFFECTS ASPIRIN + WATER SLIGHTLY SOLUBLE + SODIUM CITRATE (soluble) SOLUBILITY C. EFFECT OF PH PENICILLIN G SODIUM SOLUTION BEFORE ADDITION OF 0.1N HCl AFTER ADDITION OF 0.1N HCl AFTER ADDITION OF 0.1N HCl BASIC ACIDIC + DIPHENHYDRAMINE HYDROCHLORIDE SYRUP BEFORE ADDITION OF 0.1N HCl AFTER ADDITION OF 0.1N HCl AFTER ADDITION OF 0.1N HCl ACIDIC BASIC + AD | PHARMACY 2A | 2021 3