Routes of Drug Administration PDF

ROUTES OF DRUG ADMINISTRATION By Dr. Amany Helmy  Routes of Drug Administration Enteral Parenteral Respiratory Topical  Enteral Route Oral Buccal Rectal Gastric Gavage  Oral...

ROUTES OF DRUG ADMINISTRATION By Dr. Amany Helmy  Routes of Drug Administration Enteral Parenteral Respiratory Topical  Enteral Route Oral Buccal Rectal Gastric Gavage  Oral route Advantages Easy Safe Convenient Acceptable No need for sterilization Disadvantages Delayed onset Variable bioavailability Not suitable for some drugs Contraindications Emergency Convulsions Coma Vomiting  Buccal Route For local effect: Lozenges For systemic effect Sublingual Nitroglycerin Transbuccal Fentanyl lollipop Advantages First-pass metabolism No Onset Rapid  Rectal Route Advantages Less first pass metabolism Suitable for some patients: Children Vomiting Coma Suitable for some drugs: Aminophylline Irritant Drugs NSAIDs Drugs destroyed by GIT enzymes  Rectal Route Disadvantages Disagreeable Irregular Bioavailability Proctitis Gastric Gavage Gastric Lavage  Parentral Route Systemic Local IV Intra-articular IM Intrathecal SC Intrapleural Intradermal Around sensory Intracardiac nerve endings Intra-arterial or nerve trunks Intraperitoneal  Parenteral Route Intravenous Injection Infusion Advantages Immediate onset Used in Emergency 100% Bioavailability Blood, Fluid therapy Large volumes can be infused (saline, glucose) Irritant drugs can be given “diluted” Thiopental, Theophylline Intravenous route (cont.) Precautions No oily solutions Strict aseptic technique Exclude air Strict aseptic technique Aspirate blood Slow administration  Risk of anaphylaxis Intravenous route (cont.) Disadvantages Dose cannot be retrieved Extravasation Thrombophlebitis Need trained person Risk of infection Fat embolism Any questions  Intramuscular injection Advantages Absorption: Rapid Bioavailability: High Suitable for depot and oily preparation Disadvantages Large volumes Irritant drugs Accidental IV injections Painful Infection abscesses  Parenteral Route Intradermal- Subcutaneous-Intramuscular Vaccines Hypersensitivity tests Insulin, Heparin  Compared to IV route Rapid Onset (but not immediate) High bioavailability (up to 100%) Not suitable for large volumes (max 5 ml/injection) Not suitable for irritant drugs (painful) Disadvantages Painful due to rich nerve supply Accidental IV injections if wrong technique Abscess if no good sterilization  Compared to IV route Delayed Onset Slow steady absorption (but bioavailability is complete) Less suitable for large volumes Not suitable for irritant drugs (very painful) Disadvantages Lipodystrophy with repeated injection Absorption rate is dependent on local blood flow & injection site More painful than IM route  Other Parentral Routes Intraperitoneal Intrapleural Intracardiac Intrathecal Intra-articular Perineuronal  Respiratory Route Inhalation Insufflation Factors affecting aerosol deposition Aerosol particles size (1-5 µm) Airway patency Proper technique  Inhalation Route Suitable for pulmonary diseases e.g. Bronchial Asthma Advantages Immediate onset Low systemic adverse effect Minor first pass metabolism However its disadvantages Needs intelligent patient Some drugs  Irritation Bronchial asthma Corticosteroids  Candidal infection  Topical Route Mucous membrane Skin Eye Drops Ear Drop Ointment, Cream, Transdermal patch, …. Nasal Spray  Transdermal patch - Nitroglycerin Angina - Nicotine Smokers - Estradiol Postmenopausal syndrome - Hyoscine Motion Sickness - Fentanyl Cancer pain Gradual onset & Long duration of action No First pass metabolism Avoid disadvantages of oral drugs Local allergy, Irregular absorption, May drop off