Pharmacology deals with all aspects of drug/medicine/chemical compounds,including their source,effects,side effects,permeability,distribution,metabolism,mode of action, elimination/excretion in the body.
Biological products for diagnosis,treatment,prevention of a rare disease or condition for which there is no reasonable expectation that the cost of developing and marketing it will be recovered from the sales of that drug,e.g. sodium nitrate,potassium sulfate,calcitonin,digoxin immune,liothyronine(T 3 )
With a single diagnosed patient only, ribose-5-phosphate isomerase deficiency is presently considered the rarest genetic disease.
No single cutoff number has been agreed upon for which a disease is considered rare. A disease may be considered rare in one part of the world, or in a particular group of people, but still be common in another.
Factors governing choice of route of drug administration
Physical and chemical properties of the drug(solid/liquid/gas;solubility,stability,pH)
Site of desired action
Rate and extent of absorption of the drug from different routes
Effect of digestive juices and first pass metabolism on the drug
Special features of transdermal drug delivery system
These are devices in form of adhesive patches of various shapes and sizes,which deliver the contained drug at a constant rate into systemic circulation.
The drug is held in a reservoir between an occlusive backing film and a rate controlling micropore membrane,the under surface of which is smeared with an adhesive impregnated with priming dose of drug that is protected by another film to be peeled off just before application.