Pharmaceutical solutions

Pharmaceutical Solution 03/11/2013 0 Comments Definition Solutions are homogeneous liquid dispersion of a solute (Solid, Liquid or Gas) dissolved in a suitable vehicle (Water, alcohol or any other solvent mixture) Advantages (General Advantages of Liquid Dosage forms) 1. Young Children and some adults have difficulty in swallowing tablets and capsules 2. They are more quickly effective than, for example, tablets which must disintegrate and then dissolve in the body before absorption can begin. (Advantages of Oral Solutions) 1. Uniform dosage is certain. 2. Absorption is not delayed. 3. Safe mean of administering substances like potassium iodide and bromide that cause gastric pain if taken dry. 4. Attractive appearance adds to patient compliance. Disadvantages: (General Disadvantages of Liquid Dosage form) 1. They are less stable than solid dosage form. 2. Unpleasant flavors can be difficult to mask. 3. They are bulky to carry around. 4. A spoon is needed to administer the dose. 5. Accidental breakage of the container results in complete and messy loss of the contents. these are seldom formulated for long life because they are mainly prescribed for acute conditions like cough, diarrhea and constipation etc. Formulation: 1. Vehicles: A. Water: If in the official book only the term “water “is written, then it means potable water. I- Potable Water: If the tap water is coming directly from the water source and is not coming from any storage tank and when the water is safe for drinking then we can use this potable water for Pharmaceutical purposes. II- Freshly Boiled and Cooled Water: If the tap water is coming from a storage tank and is not safe for drinking, then freshly boil and cool this water before using it for preparation of medicine. III- Purified water: If the water is not safe for drinking and contain impurities, then purified water should be used. B. Aromatic Water Aromatic waters are mainly used for their flavoring properties although some are mildly therapeutic and or preservative in action. They are prepared by diluting a concentrated preparation to 1:39. Nowadays, the required volume of concentrated water is specified in official formula, because a superior flavor, preservative and therapeutic effect is obtained with the modified amount. C. Medicament: Some vehicles with defined therapeutic activity is prescribed. E.g, I- Gentian Infusion: A bitter that stimulates the appetite, II-Orange Peel Infusion: Bitter and carminative, III- Senegal Infusion: Expectorant, IV- Liquid liquorices Extract: Mild cough depressant and expectorant. Infusions are generally prepared by diluting 1 part of corresponding concentrate infusion with 9 parts of water but as with aromatic water this ratio is subject to change for superior activity. Most of these concentrates contain volatile oils from plants, which upon dilution with water may form light precipitate and create turbidity in the solution. Although the dispersion is very light, an instruction to shake the bottle is required. 2. Adjuncts A. Chemical Stabilizers prevent the chemical degradation of the preparation. Examples are 0.1% Ascorbic acid, 0.1% Sodium Metabisulphite etc. B. Preservatives prevent the microbial growth in the preparation. Examples include Double Strength Chloroform Water (5%), Benzoic Acid Solution (0.1%) etc. Benzoic Acid will work as preservative only in Acidic medium, and in alkaline and neutral medium it will lose its preservative activity. C. Colours and Flavours Elixirs These are hydro-alcoholic preparations usually containing more potent substances like antibiotics, antihistamines, and sedatives. Alcohol concentration is 10-40%. Elixirs are clear preparations unlike most mixture which may contain light precipitation of vegetable ingredients. Formulation: Vehicles: It is in this respect that the elixirs are most different from mixtures. The problems that contribute to these differences are: 1: Production of a clear solution 2: Solution of a medicament of low water solubility 3: Production of palatable preparations. Vehicles used are: I- Water II- Alcohol, and III- Propylene Glycol and Glycerol (is used in pediatric Elixirs where use of alcohol may cause toxicity in children) 3- Adjuncts: A. Chemical Stabilizers are many chemical agents that are used as the stabilizers like the Neomycin elixirs B.P.C are adjusted to the pH of 4 to 5 with citric acid to prevent the darkening. Moreover, addition of Disodium Edetate will prevent chemical degradation catalyzed by the heavy metal impurities in the water. B. Preservatives include Alcohol (Alcohol is preservative when it is more than 20%) and Propylene glycol. But if the elixir is to be stored and used for a longer period of time than Double strength Chloroform water, Benzoic acid solution or esters of Para-benzoic acid may be used. C. Coloring Agents are mostly the coal tar dies. D. Flavoring Agents are mostly the sweetening agents, fruit flavors and the aromatic vehicles. Major of them is the liquorice liquid extract. E. Sweetening Agents include glycerol, sorbitol, flavored and simple syrups, and saccharine sodium. 4- Linctuses These are viscous syrups meant for smoothening the throat and are used as anti-cough preparations. Formulation: Vehicles: I- Simple Syrup (Simple Syrup 66.7% w/v BP, and Simple Syrup 85% w/w USP) II-Tolu Syrup Simple Syrup B.P is the vehicle for the most linctuses but Tolu Syrup is prefer in some instances because its aromatic odor and flavor are appropriate to cough preparations and it is believed to have mild expectorant action. Adjuncts: A. Chemical stabilizers; the linctuses are mostly the stable syrups. They contain invert sugar, the reducing action of which reduces oxidative reduction of flavors and colors. B. Coloring Agents are the coal tar dyes. C. Flavoring Agents; the Tolu syrup and the aromatic syrups are used as the flavorings but we can also use the oxymel and honey flavors. D. Preservatives; Normally the chloroform spirit and the Benzoic acid are used.