capillary viscometer equation, Cheat Sheet of Chemistry

Download capillary viscometer equation and more Cheat Sheet Chemistry in PDF only on Docsity! Pharmaceutical Compounding I Lec 2 : Liquid Dosage forms, Solutions Presented By:Dr Amit Sharma Assistant Professor of the Pharmacy Department 1 Komar university OF SCIENCE AND TECHNOLOGY Outline • Liquid Dosage forms • Pharmaceutical Solution • Solubility • Preparation • Drugs • Solvents • Water • Non Polar • Excipients • Enhancing solubility • Types of pharmaceutical solutions 2 Liquid Dosage forms • Depending on the nature of interaction between solute and solvent 1. True Solution ( molecular) • Sugar dissolved in water 2. Colloidal solution 3. Disperse systems (suspension) • Sand is mixed w i th water • Antibiotics in paediaterics 5 S O L U T I O N • “one phase system of two or more substances” • Two or more substances mixed they wil l be in one state of mat ter and form homogenous mixture • E.g. Solid dissolved in l iquid • States 1. Solid: • Solid in solid, solid in liquid, solid in gas 2. Liquid; • Liquid in l iquid, l iquid in gas 3. Gas : • Gas in gas, gas in l iquid 6 Pharmaceutical Solution • Solutions are preparations in which the solid solutes (drug and excipients) are dissolved in a l iquid solvent system. • Water is the most common solvent • Organic solvents are used in combinat ion w i th water or alone 7 Advantages 3. There is no need to shake the container. 4. They facilitate swallowing in diff icult cases. • Some infants or the elderly may f ind i t hard to swallow tradit ional solid dosage forms 10 Disadvantages 1. Drug stability is often reduced in solution by: • Solvolysis , hydrolysis or oxidation. 2. It is diff icult to mask unpleasant tastes. 3. They are bulky, diff icult to transport and prone to breakages 11 Disadvantages 4. A measuring device is needed for administration. 5. Poorly water soluble drugs are diff icult to be formulated 12 Solution concentration (strength) • The USP indicates that the te rm 1. Percent weight in volume (% w/v): for solutions of solids in liquids 2. Percent volume by volume (% v/v): for solutions of liquids in liquids. 15 Preparation of solution Drug Solven t Solution 16 Preparation of solution Drug Solvent Excip ien t s Solution 17 Drug • Drug is present as molecules or ions throughout the solvent. • The drug concentration in a pharmaceutical solution must be below the saturation solubility • Avoid the possibility of drug precipitat ing out of the solvent 20 S o l v e n t s 1. Aqueous 2. Non- Aqueous 21 Aqueous • The majori ty of pharmaceutical solutions are water- based. • Water is the most commonly used solvent due to its many advantages; • Lack of toxicity (biocompatible) • Low cost • Dissolving many medicines • Giving clear solution 22 Non-aqueous solvents 1.Alcohol (Ethanol) • The most common organic solvent used in pharmaceutical solutions. • I t is of ten used as a co-solvent in oral, topical and parenteral solutions. 25 Non-aqueous solvents 2. Polyhydric alcohols • Alcohols containing more than one hydroxyl group per molecule a) Propylene glycol: • (CH3CH(OH)CH2OH) contains 2 hydroxyl groups per molecule. • It is often used as a co-solvent in oral, topical, parenteral and otic solutions. b) Glycerol: contains 3 hydroxyl groups per molecule. • It is widely used as a solvent or co-solvent w i th water, in oral and parenteral solutions. 26 Non-aqueous solvents 3.Dimethyl sulfoxide (DMSO) • Used as a carrier for idoxuridine for topical application to the skin. 27 Excipients uses in solution 1. Co-solvents • Ethanol, glycerol, propylene glycol • The concentration of ethanol should be l imi ted as i t exerts a pharmacological action fol lowing oral administration. 2. Flavouring Agents • Used to mask the taste of drugs, many of which have a very unpleasant taste. • Synthetic or naturally occurring flavourings such as vanilla, raspberry, orange oil, lemon oil are used for oral solutions. 3. Colouring Agents • A colouring agent should correlate w i th the flavouring agent, e.g. green w i th mint, red w i th cherry flavour. 30 Excipients uses in solution 4. Sweeteners • Sucrose, sorbitol, mannitol, saccharin sodium, xylitol are used to improve the palatabil ity of oral solutions. • Sugar-free preparations containing aspartame are suitable for diabetic patients 5. Antimicrobial Preservatives • Used to preserve mult idose preparations. • Examples include • Benzalkonium chloride • Benzyl alcohol • Benzoic Acid • Chlorobutanol • Combinations of parabens (methyl, propyl, butyl). 31 Excipients uses in solution 6. Antioxidants • Sodium metabisulphite, sodium sulphite, sodium bisulfate • Ascorbic acid (Vitamin C) 7. Chelating Agents • Disodium edentate, used to increase solution stability 32 Physical • Colour • Clarity • Odour 35 Chemical Stability 36 • Drugs molecules undergo chemical reactions • Hydrolysis • Oxidation • Chemical reactions occur at: • High temperature • pH • Presence of UV l ight Oxidation • To reduce photooxidation, solutions are packaged in containers that do not allow l ight transmission. • To reduce oxidation • Antioxidants • Metal chelators (as heavy metal ions catalyse oxidation) are used. 37 C o -s o lve n ts • The principle ‘like dis- solves like’. • Polar drugs generally dissolve in polar solvents • Non-polar drugs generally dissolve in non-polar solvents • Non-polar drugs are poorly soluble in water – a polar solvent. • Polarity of water can be reduced by addit ion of other solvent which is less polar or non-polar 40 C o -s o lve n ts • Examples include • Glycerol • Propylene glycol • Ethanol • The solubility of non-polar drugs in water can be increased by several orders of magni tude using co-solvents. 41 • Surface active agents • One region is hydrophil ic and the other hydrophobic. • Surfactant molecules tend to accumulate at the boundary between two phases, such as water-oil interfaces. 42