Introduction; Scope of Pharmacology Routes of Drug Administration Pharmacology I BMS 242 Lecture I (Continued) Introduction; Scope of Pharmacology Routes of Drug Administration Dr. Aya M. Serry 2017

Parenteral Route

Routes of Drug Administration Parenteral Route: Administering a drug by a needle or canula  Parenteral administration is used for drugs that are poorly absorbed (e.g: Heparin) or that are unstable in the GI tract (e.g: Insulin) Highest bioavailability ( Drug is not subject to first-pass metabolism or harsh GI environments) Treatment of unconscious and emergency patients (Rapid action)  Provides the most control over the actual dose of drug delivered to the body However, these routes are irreversible and may cause pain, fear and infections

Routes of Drug Administration  The three major parenteral routes are Intravenous(IV), Intramuscular (IM) and Subcutaneous (SC). Each route has it’s advantages and drawbacks; Intravenous Injection (IV) Advantages Disadvantages Rapid effect Maximum control over the dose of the drug reaching the blood Large quantities of drug can be injected Injected drugs cannot be recalled by emesis or by binding to activated charcoal IV injection may introduce bacteria through contamination at the site of injection May also induce hemolysis or other adverse reactions due to too-rapid delivery of high concentrations of drug to the plasma and tissues (rate of infusion must be carefully controlled)

Routes of Drug Administration B. Intramuscular Injection (IM) Advantages Disadvantages Rapid effect • Suitable for oily vehicles and certain irritating substances • Preferable to intravenous if patient must self administer Only up to 10 ml drug given Local pain Can cause intramuscular hemorrhage

Routes of Drug Administration C. Subcutaneous Injection (SC) Advantages Disadvantages Suitable for slow-release drugs (Insulin is the most famous example of SC injections) Ideal for some poorly soluble suspensions Pain and inflammation at site of injection Injection site should be changed frequently to avoid tissue damage Unsuitable for drugs administered in large volumes

Routes of Drug Administration Advantages: Other Routes: Topical route Used when a local effect of the drug is desired. Drug is applied directly to the skin or mucous membrane (e.g: Skin and eyes)

Routes of Drug Administration Advantages: Other Routes: Transdermal route This route achieves systemic effects by application of drugs to the skin via a transdermal patch The rate of absorption varies depending on the physical characteristics of the skin This route is most often used for the sustained delivery of drugs, such as the anti-anginal drug nitroglycerin and the once-a-week contraceptive patches

Routes of Drug Administration Other Routes: Oral Inhalation Inhalation provides the rapid delivery of a drug across the large surface area of the mucous membranes of the respiratory system Rapid effect (almost as rapidly as with IV injection) Used for drugs that are gases or those that can be dispersed in an aerosol This route is mainly effective for patients with respiratory complaints (as asthma)

Routes of Drug Administration Advantages: Other Routes: Nasal Inhalation This route involves administration of drugs directly into the nose. Agents include nasal decongestants such as the anti-inflammatory corticosteroids