Pharmacy Orientation Lecture 4 & 5 PDF

Nile Valley University Faculty Of Pharmacy Pharmacy Orientation Code: PT101 Credit hour: 1 Lectures number: )4and 5( Pharmaceutics and pharmaceutical...

Nile Valley University Faculty Of Pharmacy Pharmacy Orientation Code: PT101 Credit hour: 1 Lectures number: )4and 5( Pharmaceutics and pharmaceutical technology Department  Route of administration Route of administration is the path by which drug , fluid, poison or other substance is brought into contact with the body  A drug an agent intended for use in diagnosis, treatment, cure, or prevention of disease in humans or other animals. After administration of a drug a successful therapeutic response will be achieved if the drug reaches the suitable site of action or "receptor" site in sufficient concentration to exert its pharmacological action. This is achieved by the drug being absorbed into the body tissues from the site of administration. The choice of administration site depends on different factors such as whether a local or systemic action is required or how quickly a response to the drug is needed. Drug may be taken by Oral Buccal Sublingual Rectal Vaginal inhalation topical  Oral route  The oral route is used to obtain either systemic or local effects  The drug formulated in either solid or liquid form is absorbed from gastro intestinal tract (G.I.T.)  It is the commonly used route for drug administration  Advantage and disadvantages of oral route Advantages Disadvantages The onset of action is relatively slow It is the simplest route Absorption from G.I.T. may be irregular of administration Certain drugs are destroyed by enzymes Self administration of and other secretions found in G.I.T. drugs can be carried Drug solubility can be altered by out presence of other substances in G.I.T. It is the safest route of e.g. Calcium administration Slow gastric emptying drug inactivation by prolonged contact with gastric juices specially in elderly peoples It is unsuitable route in unconscious or vomiting patients  Buccal route  A drug administered by this route is formulated as tablet  The high vascularity of the tongue and bucchal cavity and the presence of saliva facilitates the dissolution of drug making this route highly effective  The tablets formulated for this route give quick onset of action  Advantage of buccal route Advantages Dis advantages Relatively quick onset of action Short duration of action Drugs absorbed directly into the systemic circulation avoiding the first pass effect Drugs can be administered to unconscious patients Antiemetic drug can be given by this route  Sublingual route For sublingual absorption, the area under the tongue is used. This gives a very fast onset of action but the duration is usually short.  Rectal route Drugs administrated by this route are formulated as liquids (enemas) solid (suppositories) and semisolids (creams – ointments) dosage form This route is used for both systemic and local effects The rectum is supplied by three veins middle and inferior upper rectal vein drain directly to the general drains into the portal vein and then circulation flows to the liver. This means that some of the drugs absorbed from the rectum can be subjected to the first pass effected therefore bioavailability may be less than 100%  Advantage and disadvantages of rectal route Advantages Disadvantages Can be used when the oral route is unsuitable e.g. Absorption can be irregular vomiting, unconscious variable effect patient, elderly or mentally Less convenient than oral disturbed patients route Useful when the drug Low patient acceptability causes G.I.T. irritation Can be used for local action  Vaginal route drugs administrated by this route are formulated as pessaries and oblong tablets (solid) or creams and ointments (semisolids) vaginal douches (liquid) These are inserted into the vagina This route can be used for both local and systemic effect advantages Drugs from the vagina are not subject to the first pass effect The higher fluid content in the vagina drugs dissolution is more efficient than by the rectal route  inhalation route In this route drugs are inhaled through the nose or mouth to produce either local or systemic effect This route is used mainly to treat respiratory conditions therefore drugs here are delivered to the site of action lungs Because of the large surface area rapid drug absorption Advantage of inhalation route  disadvantage of inhalation route Very costly Irritant effect on airways Limitation of medication dose due to airway symptoms Delivery systems can be cumbersome and time consuming  Topical route This route means that the skin is used as the site of administration This route is mainly used for local effects The formulations used include ointments, Creams and pastes (semisolids) lotions (liquids) Recently specialized dosage forms are developed when applied to the skin give systemic action by passing through skin layers to the blood these called transdermal dosage forms (patches)  Advantage and disadvantages of topical route Advantages Disadvantages Avoidance of first pass metabolism  Skin irritation Easy application  Poor permeability of some drugs Achievement of efficiency with lower total through the skin daily dosage of drug by continuous drug input  Enzymes in epidermis may be Suitable of self medication denature some drugs Improved patient compliance  Can be used only for drugs Improved physiological and pharmacological required low plasma response concentration for action Avoidance of gastro-intestinal incompatibility  Parenteral route This is the term used to describe drugs given by injection  Injections administered by many routes, which are described as follows: Intravenous rout ( i.v) –Drugs injected directly into the systemic circulation –This produces a very fast onset of action Intramuscular route ( i.m) – Drugs injected into the muscle layers – Used to produce a fairly fast onset of action specially when formulated in liquid forms – A slower or prolonged action well occur when the drug is presented as suspension or in oily form Subcutaneous Route (S.C) – Drugs are injected into the subcutaneous layer of the skin – Easiest and least painful type of injection – Slower onset of action but prolonged e.g. insulin Intradermal injections ( I.D) –Injected into the skin between the dermis and epidermis – Small volumes are injected (0.1 – 0.2 ml) –Mainly used for diagnosis of allergy and immunity Intra-arterial injection: Administered directly into an artery Mainly used for diagnosis e.g. X- ray contrast  Intraspinal Route: –Used to administer spinal anesthetics –Injection are made into the subarachnoid space (intrathecal) or peridural space (peridural) or into the cisterna magna (interacisternal) Intraarticular route – Made into the synovial fluid of joint – Used for the localized administration of corticosteroids as anti- inflammatory agents