Routes Of Drug Administration PDF

Routes Of Drug Administration  Enteral 1- Oral 3- Rectal 2- Buccal 4- Gastric gavage Parental 1- Injection 2- Subcutaneous implantation Inhalation Topical  I) Enteral...

Routes Of Drug Administration  Enteral 1- Oral 3- Rectal 2- Buccal 4- Gastric gavage Parental 1- Injection 2- Subcutaneous implantation Inhalation Topical  I) Enteral 1) Oral Oral agents should be: 1) palatable, 2) non-irritant, 3) stable at PH of GIT 4) absorbed to produce systemic effects. Advantages Disadvantages Contraindications 1- Easy 1- Delayed onset of action. 1- Emergency. 2- Most convenient & 2- Not suitable in some 2- Convulsions. acceptable. conditions. 3- Vomiting. 3- Safe 4- Coma. 4- Economic.  2) Buccal The drug administered through buccal route should be: 1) Palatable. 2) Not irritant. 3) Very effective in small dose due to small surface area of absorption. 4) Highly soluble in saliva. 5) Highly non-ionized to diffuse freely across cell membrane. Types of buccal route: 1) Sublingual: drug is absorbed through mucosa under the tongue to reach systemic circulation directly 2) In the buccal pouch (can be used for local effects) e.g. lozenges, mouth wash, gargle & oral gel. 3) Trans-buccal patch e.g. Fentanyl.  Sublingual: Advantages Disadvantages 1) Easy 1) Irritation of mucous 2) Bypasses first pass metabolism. membrane. 3) Avoids GIT enzymes & PH. 2) Excessive salivation promotes 4) Rapid onset. swallowing. 5) The patient can get rid of excessive dose.  3) Rectal Drugs are absorbed through rectal mucosa to reach systemic circulation. Examples: NSAIDs. Advantages Disadvantages Contraindications 1) Less first pass metabolism. 1) Irregular bioavailability Diarrhea 2) Suitable for children, in (absorption is unreliable). presence of vomiting & in 2) Disagreeable. comatosed patients. 3) Chronic use leads to 3) Suitable for drugs irritant to proctitis. gastric mucosa e,g. aspirin. 4) Rapid onset & prolonged duration of action.  3) Oral Gavage 1. Introduction of food or drugs into stomach by flexible tube e.g. Rayel tube. 2. Used in coma. 3. It is opposite to lavage (washing out stomach in poisoning). II) Parental: using syringes A-Injections  1) Intravenous Can be used for bolus injection or infusion. Only sterile aqueous solutions can be given by this route. Drugs should be: 1. Non-oily solutions 2. No potential allergy. 3. Well-diluted solution to avoid local phlebitis. Advantages Disadvantages 1) Immediate onset 1. Aseptic conditions AND trained person 2) 100% bioavailability 2. Transfer of diseases and infection 3) Suitable for irritant drugs 3. Once the drug is injected, it cannot be retired. & for large volumes 4. Prolonged infusion → high risk of thrombophlebitis. 5. Wrong technique → air embolism.  2) Intramuscular 1. It is suitable for aqueous or oily solutions and suspensions of insoluble drugs. 2. Drugs pass through capillary walls to enter the blood stream. 3. Oil-based preparations are absorbed slowly. 4. Aqueous preparations are absorbed rapidly. Advantages Disadvantages 1) Rapid absorption (onset of action 1) Unsuitable for large volumes (> 5 between 10 – 15 min). ml) & irritant drugs. 2) High bioavailability. 2) Abscesses. 3) May be painful.  3) Subcutaneous Drugs are injected in the subcutaneous tissue (hypodermis) and absorbed through capillaries to reach systemic circulation. Site of injection: areas that are relatively distant from nerves and major vessels 1. Lateral of the arms. 2. Thigh and abdomen for frequent injection. Advantages Disadvantages 1) Suitable for non-irritant drugs in 1) Repeated injection at the same site aqueous solution or suspension. → lipoatrophy. 2) Acceptable for self-administration 2) Erratic absorption. 3) Irritant.  4) Intradermal 1) Injection between dermis & epidermis (0.1 ml). 2) Site of injection: ventral forearm 3) Do not massage the area because massage can cause irritation. Indications: 1. Allergy tests. 2. Vaccinations. 3. Desensitization  Other injection sites 1. Intrathecal 2. Intracardiac 3. Intra-arterial 4. Intraperitoneal 5. Intra-articular B- Subcutaneous Implantation Solid pellet Implanted under skin Absorption occurs slowly over a period of several weeks or months  III) Inhalation Advantages Disadvantages 1. Immediate onset of action. 1. Needs cooperative patient. 2. Minor first pass metabolism. 2. Respiratory irritation 3. Low incidence of systemic side effects. 3. Irregular absorption & dosage. 4. High concentrations in respiratory tract. 4. Laryngitis 5. Large surface area for absorbable drugs  IV) Topical Route Advantages Disadvantages 1) Long duration 1) Variable absorption. 2) Gradual onset 2) Local allergy. 3) No first pass metabolism. 3) The sticking plaster may drop off & stick 4) No GIT irritation. to another person. 5) Not destroyed by GIT enzymes Transdermal delivery system (TDS) ❖ Few drugs can be formulated as a patch containing the drug that can be applied to the skin by adhesive plaster. ❖ The drug seeps out of the patch, through the skin into the capillary bed.  Q1: Complete: 1. Oral route not suitable in ………. , ……….. , ……….. and …….. 2. Rectal route is suitable for …………. drugs. 3. Lavage is ……………. 4. Intradermal injection used for …………. and …………. Q2: Indicate () or (×) for the following statements : 1. No first pass metabolism in sublingual route. ( ) 2. Oral route is suitable for hydrophilic drugs. ( ) 3. I.V. route is not suitable for irritant drugs. ( ) 4. Large volumes can be administered intramuscular. ( ) 5. S.C drugs may cause lipoatrophy. ( )