Routes of Drug Administration PDF

DR. HODA TEBA Routes of administration Definition: The way to get a drug into or onto the body. (e.g. oral, topical, rectal, vaginal, nasal,…….. )  Sometimes, combinations of routes are used at the same time. Routes of administration Classification: I. Enteral involves absorption of the drug v...

DR. HODA TEBA Routes of administration Definition: The way to get a drug into or onto the body. (e.g. oral, topical, rectal, vaginal, nasal,…….. )  Sometimes, combinations of routes are used at the same time. Routes of administration Classification: I. Enteral involves absorption of the drug via the gastrointestinal tract (GIT) II. Parenteral routes of administration that do not involve drug absorption via the GIT III. Topical the application of a drug directly to the surface of the skin & mucous membrane. Routes of administration I. ENTERAL ROUTES Involves absorption of the drug via the gastrointestinal tract (GIT) Includes : 1) Oral 2) Sublingual 3) Buccal 4) Rectal Routes of administration I. ENTERAL ROUTES 1) O r a l Ro u t e Applying topically to the mouth Methods of administration administered orally through the mouth & swallowed to reach the stomach [Peroral Route] Routes of administration I. ENTERAL ROUTES 1) O r a l Ro u t e It is the most commonly used route of administration.. Why? due to the following advantages:  Safe  Convenient  Painless  No strict sterilization required  Cheap Routes of administration I. ENTERAL ROUTES 1) O r a l Ro u t e Oral route is not suitable for:  Unpalatable and highly irritant drugs  Unabsorbable drugs (e.g. aminoglycosides)  Drugs that are destroyed by digestive juices (e.g. insulin)  Drugs with extensive first-pass metabolism (e.g. lignocaine)  Unconscious patients  Uncooperative patients  Patients with severe vomiting and diarrhea  Routes of administration I. ENTERAL ROUTES 2) Su b l i n g u a l R o u t e The dosage form is placed under the tongue to be rapidly absorbed in blood circulation by sublingual mucosa. Advantages Disadvantages Quick onset of action  Irritation of oral mucosa. Avoid the first-pass metabolism  Large quantities of drug cannot be given.  Few drugs are absorbed. First Pass Metabolism It is the first pass of the drug through the liver.  Drugs that are absorbed via the GIT are circulated to the liver first via the hepatic portal vein.  Liver then act as a filter.  Only part of the drug reaches the systemic circulation.  Oral bioavailability of the drug is decreased.  Routes of administration I. ENTERAL ROUTES 3) Buccal Route It involves placing a drug between your gums and cheek, where it dissolves and is directly absorbed through the buccal mucous membrane into blood stream. Advantages Disadvantages  Quick onset of action  Inconvenient  Bypasses first-pass metabolism.  The advantages lost if swallowed  Small dose limit Routes of administration I. ENTERAL ROUTES 4) RECTAL ROUTE most commonly given as: Suppository or Enema Advantages  Useful in patients with nausea & vomiting  Useful if the drug is irritant  Useful if the drug has unpleasant taste  Bypasses first-pass metabolism Disadvantages  Inconvenient Routes of administration II. PARENTERAL ROUTE par = around enteral = gastrointestinal 1) 2) 3) 4) Routes of administration II. PARENTERAL ROUTE Reasons for choosing a parenteral route over the oral route include: Drugs with low oral bioavailability (high first pass metabolism). Drugs that irritate the GI tract. Patients who are unable to take the drug by mouth The need for immediate effect (e.g., emergency situations)  Routes of administration II. PARENTERAL ROUTE 1) Intravenous (I.V) Route In this route, drugs are injected directly into the blood stream through a vein.  Advantages:  Disadvantages: 1. Bioavailability is 100%. 1. Action cannot be stopped 2. Quick onset of action. 2. Strict aseptic conditions are needed 3. Not suitable for depot preparations Routes of administration II. PARENTERAL ROUTE 2) Intramuscular (I.M) Route It involves inserting a needle into the muscle tissue  Advantages: 1. more rapid absorption than oral route. 2. Suitable for depot injections. Routes of administration II. PARENTERAL ROUTE 3) Subcutaneous (S.C) Route The drug is injected into the subcutaneous tissues of the thigh, abdomen or arm, e.g. insulin  Advantages: 1. Self-administration is possible (e.g. insulin). 2. Depot preparations can be used  Disadvantages: absorption is slow; hence it is not suitable for emergency Routes of administration II. PARENTERAL ROUTE 4) Intradermal (I.D) Route The drug is injected into the dermis layers of the skin e.g. - vaccination - drug sensitivity tests - local anesthetics  Advantages: Have the longest absorption time Routes of administration II. PARENTERAL ROUTE 4) Intradermal (I.D) Route  Disadvantages: It is painful. Only a small amount of the drug can be administered (maximum 2 ml) Routes of administration II. TOPICAL ROUTE It means; application of a drug directly to the surface of the skin, and to any mucous membrane of eye, nose, ears, lungs, vagina, urethra and colon. It includes; 1) Ophthalmic route 2) Nasal route 3) Otic route 4) Vaginal route 5) Transdermal route Routes of administration II. TOPICAL ROUTE 1) Ophthalmic Route must be sterile available in ointment or eye drops 2) Nasal Route Advantages:  First-pass metabolism is absent.  Rapid drug absorption. Routes of administration II. TOPICAL ROUTE 3) Otic Route application of drug to the ear canal to treat infections, inflammation and several wax build-up Routes of administration II. TOPICAL ROUTE 4) Vaginal Route used for the delivery of contraceptive hormones Examples: Vaginal ring doughnut-shaped polymeric drug delivery device Intrauterine devices (IUD) A small, T-shaped birth control device that is inserted into a uterus to prevent pregnancy  Routes of administration II. TOPICAL ROUTE 4) Vaginal Route used for the delivery of contraceptive hormones Examples: Vaginal ring Intrauterine devices (IUD) doughnut-shaped polymeric A small, often T-shaped birth drug delivery device control device that is inserted into a woman's uterus to prevent pregnancy. Routes of administration II. TOPICAL ROUTE 5) Transdermal Route is used to for delivery of the drug via absorption through the skin by using a drug-containing patch or disc. It has systemic effect  Routes of administration The selection of routes of administration depends on Drug & patient-related factors which are: 1. Characteristics of the drug. Drug 2. Emergency/routine use. 3. Site of action of the drug (local or systemic). 1. Condition of the patient (unconscious, vomiting, diarrhea). Patient 2. Age of the patient. 3. Patient’s/doctor’s choice (sometimes). 