Dosage form of Drugs&Route of drug administrationBy Abubakar salisu fago.
Drug substance are seldom administer alone; rather they are given as part offormulation in combination with one or more non-medicinal agents that servevaried and specialized Pharmaceutical functions. Selective uses of nonmedicinal agent referred to as pharmaceutical ingredients or excipients,produces dosage form of various types.Pharmaceutical ingredients solubilized, suspend, thicken, dilute, emulsify,stabilized, preserve, color, flavor and fashioned medicinal agent into efficaciousand appealing dosage forms.Dosage form is mixture of medicinal substance and excipients together so thatthey designed in definite form , size , shape, color and in appearances. Dosageform is the way of identifying the drug in its physical form. In determiningdosage form, FDA examines such factors as(1) physical appearance of the drug product,(2) physical form of the drug product prior to dispensing to the patient,(3) the way the product is administered,(4) frequency of dosing, and(5) how pharmacists and other health professionals might recognize andhandle the product."
Each type of dosage form is unique in physical and pharmaceutical characteristics.Depending on the type of administration they come in several typesSolid
Powders: oral unite dosage form thatnowadays rarely preparedextemporaneouslyPowder may be prescribed in the form of1. Bulk powders for (oral) internal use-eg.Gregory powder ( compound BPC)Heavy Mg carbonate- 325gLight Mg carbonate 325 gRhuberb in powde- 250gGinger in powder- 100g2. Bulk powder for external use-dusting powder and insufflationsDusting powder two types ( free flowingfine powder for external usesMedical- these are used for superficial skincondition and rarely require to be sterile.However they should be free fromdangerous pathogens. Thet are notintended to use in open wounds.Eg. Light kaoline, talc, starch and zinc oxideSurgical dusting powders;These are used in body cavity and majorwounds. They often containantibacterial agents.Eg. Chlorhexidine powdersHexachlorphen powdersNeomycin sulfate powdersSome times, oral solution and syrup oreven I.V preparation dispense in theform of powderEg. Paracetamol dry syrupCephadoxile dry syrup( they require to add vehicle when use)Neomycinesulfate, polymaxinB andDexomethasone
Granules:Solid dosage form oral preparation for large volume of medicamentswhere the active ingredients are compressed together withexcipients to form suitable granules and passed through suitablesieve.Eg. Methyl cellulose granulesSodium Amino salicylate ( 6-12gm) for TBAdvantages of granules:a. Some time it is difficult to find satisfactory presentation ofmedicament with large dosages.b. Tablet and capsule may be impractical because of size and numberof frequencyc. Liquid dosage forms are avoided due to instability in moisture.d. Administration of powder form is difficult due to unpleasant teste. Suitable amount of coloring, flavoring and sweetening agent canbe included.
Tablets:Solid dosage form where powders are moulded into tablets. Theyare flat, circular dices usually contain a potent medicament mixedwith sucrose, lactose, dextrose or any other suitable diluents alongwith sufficient binding, coloring and flavoring agents. They areintended for oral use, require prior dissolution upon contact withmoisture of the stomach. Thus tables avoided ingredient those arenot soluble in water.Capsules:Solid dosage form intended for oraladministration containing active ingredientsalong with suitable fillers. They are twotypes.1. Hard gelatin capsules:They consist a cylindrical body and cap, bothwith hemispherical ends, and are made fromgelatin and water with added preservatives.Although they are quite hard, they softenand dissolve after swelling with water2. Soft gelatin capsules: are for solid, liquidsand semisolid liquids. They may be spherical ,ovoid or cylindrical. In addition to theingredients of hard capsules, they containglycerol which provide the flexibility.
Modified Release dosage forms (Tablet/Capsule)In contrast to conventional ( Immediately release)forms, modified –release products provide eitherdelayed release or extended release of drugs. Mostdelayed release products are enteric coated tabletsor capsules designed to pass through the stomachunaltered, later to release their medication withinthe intestinal tract.Delayed release product are used either to protectthe substance from destruction by gastric fluids orto prevent stomach distress.Extended release Products are designed to releasetheir medication in a controlled manner, atpredominant rate, duration and location to achieveand maintain optimum therapeutic blood levels ofdrugs.
Lozenges: (torches)These are solid preparationconsisting mainly sugar andgum. Gum uses for increasingthe hardness of preparationthus ensure slow release ofmedicaments. They are use tomedicate the mouth and throatand for slow administration ofindigestion and coughremedies.
Semisolid Dosage formsOintments: are semi-solid greasypreparation for application to the skin ormucosa. The base is usually anhydrousand containing medicaments in solutionor suspension.They are generally used for theira. emollient effectsb. protection effect of lesionsc. topical application of medicationseg.Acne- Sulphur or resorcinol ointmentAntibiotic- bacitracine, chlortetracyclineAnti-inflammatory- BetamethasoneAnti-septic- Zinc oxideDandruffs- Salicylic acidCounter irritant- Capcisin
Creams:These are semisolid emulsion forexternal use. There are two kinds,aqueous and oily cream, in which theemulsion are Oil in Water (O/W) orWater in Oil (W/O). The oil in water typeare relatively non-greasy.Cream are of two type cold cream andvanishing creams. Vanishing cream is anoil in water type of emulsion whereascold cream is of water in oil type ofemulsion. They also differ in their pH.vanishing cream is of neutral to slightlyacidic pH but cold cream is of neutralpH. Vanishing creams are easilywashable but cold creams can not beremoved from the skin easily.