Pharmaceutics I PT 303 PTC 303 Lecture 1 PDF

Pharmaceutics I PT 303 PTC 303 Exam Mark Quiz 20 practical 40 Pharmaceutical solution Final 75 Lecture 1 Oral 15  General definition of solution Homogenous one-phase system consisting of two or more components; on...

Pharmaceutics I PT 303 PTC 303 Exam Mark Quiz 20 practical 40 Pharmaceutical solution Final 75 Lecture 1 Oral 15  General definition of solution Homogenous one-phase system consisting of two or more components; one of them is uniformly and completely distributed within the other. The solvent: the phase in which the dispersion occurs The solute: the component which is dispersed as molecules or ions in the solvent. The solute could be solid, liquid, and gas.  Pharmaceutical solution Liquid preparation in which the therapeutic agent (drug) and various excipients are dissolved in chosen solvent system (vehicle).  1-Can be formulated for different routes of administration Advantages of solution Orally (Syrup, Elixirs, and Drops) In mouth &throat (Mouthwash, gargle) In body cavities (Douches, enemas, ear drops) Topical (collodions, lotions) 2-Easier to swallow to individuals who have difficulty in swallowing, e.g. elderly patients, infants 3- The bioavailability of pharmaceutical solutions is greater than that of oral solid-dosage forms. 4-The therapeutic response is faster than a solid dosage form that require dissolution step before drug absorption takes place. 5- Homogenous (uniform dose than suspension or emulsion which need shaking before use). 6-Dilute the irritant effect of some drugs (e.g. aspirin) and minimize the adverse effects in the GIT.  1-Unsuitable for therapeutic agents that are chemically unstable in the presence of Disadvantages of solution water, e.g. antibiotics Disadvantages of 2-Poor solubility of certain therapeutic agents may Solutions prohibit their formulation as pharmaceutical solutions 3-Expensive to ship and are bulky to carry 4-Glass bottles are liable to be broken 5-Difficult to mask the unpleasant taste 6-A measuring device is needed for administration 7-Excellent growth media for bacteria and microbial contamination so a preservative is required Methods of solution preparation 1. Simple Solutions Method 2. Solutions by chemical reactions 3. Solutions by Extraction 1- Simple solutions method Solute substance is dissolved in a solvent (by stirring or heating). N.B: The finer a drug is in subdivision, the more quickly it will be soluble. Simple solutions are used both as complete medicinal agents and as vehicles or ingredients in more complex preparations. Examples: Calcium hydroxide topical solution, USP (lime water) Strong iodine solution, USP (lugol’s solution) Heating aids in the preparation of solutions it may be desirable when preparing solutions except when: 1.The solvent will deteriorate from heat. 2.A volatile or aromatic liquid, if hot, would result in loss of the volatile substance. 3.The solute may be totally or partially decomposed by the heat e.g. chloral hydrate or sodium bicarbonate. 2. Solutions By "Chemical Reaction“ By reacting two or more solutes with each other in a suitable solvent. e.g. Magnesium citrate solution (Magnesium carbonate + Citric acid) 3. Solutions by Extraction Drugs of vegetable or animal origin often are extracted with water or with water containing other substances. Preparations of this type may be classified as solutions but more often, are classified as "Extractives". The Vehicle A vehicle is the medium containing the ingredients of drug. In solutions, the vehicle is the solvent. The choice of a vehicle depends on: The intended use of the preparation The nature & physicochemical properties of active ingredients. Classification of solutions according to the nature of the vehicle Aqueous solutions Viscid aqueous solution Non-aqueous solutions Aqueous Solutions These vehicles may be: 1.Water 2.Aromatic water 3.Extracts (aqueous acids) 1.Water Water is the most widely used solvent for use as a vehicle Advantages Disadvantages It is tasteless Favorable medium for many chemical reactions Inert(pharmacologically inactive) Support the growth of microorganisms when contaminated Lack of toxicity In pure form, add cost to the product Dissolve wide range of materials Types of Water A. Potable water (Tap water) B. Freshly boiled & cooled water C. Purified water D. Water for injection Types of water a) Potable water (Tap water) Not permitted for the dispensing of pharmaceutical dosage forms due to: Possible bacterial contamination Presence of dissolved salts b) Freshly boiled and cooled water Boiling can destroy vegetative bacteria BUT on storage for long time spores may yield vegetative microorganism Structure produced by bacteria to resist extreme conditions c) Water For Injection (WFI) Purified water free from pyrogens (bacterial endotoxins & exotoxins) Used as a solvent in parenteral solutions N.B: Sterile does not mean pyrogen-free d) Purified water Used in preparation of aqueous dosage forms except those intended for parenteral administration Methods for preparing Purified water 1-Distillation 2-Deionization 3-Reverse osmosis Removal of impurities by Removal of ions from water boiling of water then Removal of dissolved salts and replace them with H+ and condensing the steam into a in water by using semi- clean container to obtain OH- ions by using ion exchange permeable membrane and distilled water. resins to obtain deionized applying pressure. water. Aqueous Solutions These vehicles may be: 1.Water 2.Aromatic water 3.Extracts (aqueous acids)  2- Aromatic Waters “Medicated Waters“ Clear, saturated aqueous solutions of volatile oil or other aromatic or volatile substances. Their odors and tastes are similar to those of the drugs or volatile substances from which they are prepared. They are used principally as flavored or perfumed vehicles.  1- Incompatible with soluble salts due Disadvantages of aromatic water to “Salting -out ". Disadvantages of Solutionsa 2-They are sensitive to light and excessive heat, and so must be kept in cool dark places. 3-Deteriorate (become cloudy) with time and should be freshly prepared. Methods of Preparation of Aromatic Water Distillation method Solution method 1- Distillation method "Orange flower water“  Placing the odoriferous portion of the plant in still with water and then distilling most of the water.  The aqueous phase, which may require further clarification, is the product.  Excess oil in distillate removed by filtration.  Distillate may be returned to the still several times with fresh drug to get saturated aromatic water.  This method is slow and expensive. 2- Solution method " Peppermint water “ a) Volatile substance is agitated with purified water for a period of 15 minutes. b) Set aside for at least 12 hours, to ensure saturation. c) Filter.  This method is simple, quick and economic. Stability of aromatic water Unstable Should be protected from excessive light and heat Must be kept in cool and dark places. Deterioration occur due to: Volatilization Decomposition Mold growth Cloudy preparation disagreeable odor  Examples on pharmaceutical solutions Aqueous Viscid Aqueous Non-Aqueous Douches Syrups Collodions Enemas Honey Elixirs Gargles Mucilage Spirits Mouthwashes Jellies Tinctures Nasal washes Linctus Sprays Liniments Otic solutions Glycerins Examples of pharmaceutical aqueous solutions 1. Douches 2. Enemas 3. Gargles 4. Mouthwashes 5. Nasal washes 6. Sprays 7. Otic solutions 1- Douche (eg, vaginal douche) Device used to introduce a stream of water into the body for medical or hygienic reasons. A douche bag is used for holding the fluid used in douching. To avoid transferring intestinal bacteria into the vagina, the same bag must not be used for an enema and a vaginal douche. Disadvantages Frequent douching results in an imbalance of the pH of the vagina, and thus may put women at risk for possible vaginal infections. 2- Enemas The high liquid content causes expansion of the lower intestinal tract, resulting in cramping, and peristalsis, a feeling of extreme urgency and evacuation. Use Constipation Introducing liquids into the rectum and colon via the anus. Advantages Can by-pass the first pass effect (high bioavailability). Disadvantages Electrolyte imbalance (repeated enema) Ruptures to the bowel or rectal tissues resulting in internal bleeding. Exposure to infections. 3- Gargles Solutions containing antiseptics, antibiotics or anesthetics used for treating the pharynx and nasopharyngs by forcing air from the lungs through the gargle that is held in the throat; subsequently, the gargle is expectorated. Uses: Sore throats, viral respiratory infections like colds, or sinus infections. Topically as a 1.5-3% solution for cleansing wounds. Advantages: Rapid relief of pharyngeal and oral pain by gargles. 4- Mouthwash (Mouth rinse) Use Enhance oral hygiene Antiseptic Anti-plaque mouth rinse kill the bacterial plaque causing caries, gingivitis, and bad breath Helps fight early gum disease/gingivitis  Disadvantages 5- Nasal solutions Bioavailability decreases as the molecular Solutions designed to be administered to the nasal passages in drops or sprays. weight of a compound increases. Advantages Use Highly vascularized tissues making it good Reduce nasal congestion (naphazoline) site for rapid systemic absorption. Medication Delivery: Corticosteroids Antihistamines, Hormones,……. It avoids first pass metabolism. Nasal Irrigation: For peptides and small molecular compounds, intranasal, bioavailability has been comparable to that of injections. 6- Otic Solutions (ear preparation) Otic solutions may contain appropriate buffers, solvents and dispersants usually in an aqueous solution. Use Removal of excessive ceriman (ear wax) Treatment of ear infections, inflammation or pain. Advantages Rapid delivery of drugs to the site action of action. Disadvantages Sometimes can’t give appropriate quantity It sometimes creates skin irritation