ROUTE OF DRUG ADMINISTRATION Julaeha, M.P.H., Apt

Routes of Drug Administration Important Info The route of administration (ROA) that is chosen may have a profound effect upon the speed and efficiency with which the drug acts

The possible routes of drug entry into the body may be divided into two classes: Parenteral Enteral

Routes of Administration

Parenteral Routes Intravascular (IV, IA)- placing a drug directly into the blood stream Intramuscular (IM) - drug injected into skeletal muscle Subcutaneous - Absorption of drugs from the subcutaneous tissues

I. PARENTERAL A. Intravenous B. Intra-arterial C. Intramuscular Injection sites for IM administration From: Fundamentals of Nursing, 4th edition, Lippincoitt, Williams & Wilkins

Intravascular Absorption phase is bypassed (100% bioavailability) 1.precise, accurate and almost immediate onset of action, 2. large quantities can be given, fairly pain free 3. greater risk of adverse effects a. high concentration attained rapidly b. risk of embolism (penyumbatan pembuluh darah)

Intramuscular very rapid absorption of drugs in aqueous solution Repository (tempat penyimpanan) and slow release preparations pain at injection sites for certain drugs Z-track method for IM injections

Subcutaneous slow and constant absorption Sites for SC injection slow and constant absorption absorption is limited by blood flow, affected if circulatory problems exist concurrent (bersamaan) administration of vasoconstrictor will slow absorption

Aradigm Intraject® NFI device in protein delivery Reproduced from: http://www.drugdeliverytech.com/cgi-bin/articles.cgi?idArticle=178

Enteral Routes Enteral - drug placed directly in the GI tract: sublingual - placed under the tongue oral - swallowing (p.o., per os) rectum - Absorption through the rectum

Oral Advantages Convenient - can be self- administered, pain free, easy to take Absorption - takes place along the whole length of the GI tract Cheap - compared to most other parenteral routes

Oral Disadvantages Sometimes inefficient - only part of the drug may be absorbed First-pass effect - drugs absorbed orally are initially transported to the liver via the portal vein irritation to gastric mucosa - nausea and vomiting destruction of drugs by gastric acid and digestive juices effect too slow for emergencies unpleasant taste of some drugs unable to use in unconscious (tidak sadar) patient

Sublingual/Buccal Some drugs are taken as smaller tablets which are held in the mouth or under the tongue. Advantages rapid absorption drug stability avoid first-pass effect Disadvantages inconvenient small doses unpleasant taste of some drugs

Isosorbide concentrations after a 5 mg oral or sublingual dose. Data from: Assinder et al. J Pharm Sci 66:775, 1977.

Rectal unconscious patients and children if patient is nauseous or vomiting easy to terminate exposure absorption may be variable good for drugs affecting the bowel (bag paling bawah) such as laxatives irritating drugs contraindicated

avoid first-pass effect RECTAL ROUTE Local action e.g. rectal route is used primarily for the treatment constipation Systemic action Advantage avoid first-pass effect

VAGINAL ROUTE local action systemic action Marketed preparations include several feminine hygeine preparations, contraceptives, and labor inducing drugs. Advantage avoid first-pass effect Disadvantage The thickness of the vaginal epithelium and the blood circulation in this region changes with menstrual cycle and age, and the drug absorption also changes accordingly.

Dosage forms suitable for vaginal route tablet suppository ointment gel solution emulsion foam

Pharmacologic Agents Administered III. PULMONARY Pharmacologic Agents Administered via Inhalation For Systemic Effects pentamidine halothane ergotamine methoxyflurane enflurane isoflurane nitrous oxide For Local Effect beclomethasone terbutaline cromolyn metaproterenol albuterol pirbuterol

Inhalation/Pulmonary gaseous and volatile agents and aerosols rapid onset of action due to rapid access to circulation large surface area thin membranes separates alveoli from circulation high blood flow Particles larger than 20 micron and the particles impact in the mouth and throat. Smaller than 0.5 micron and they aren't retained.

Forms of pulmonary delivery Metered dose inhaler Dry powder inhalers Nebulizer

Metered Dose Inhaler (MDI) Metered-dose inhalers (MDI) provide medication with compressed gas deliver specific measured dose with each activation typical MDI

Techniques for use of MDI devices: Use of space or holding chamber Placement of inhaler in mouth (not for use with steroids) Two finger width from mouth Patient must coordinate inhalation and actuation of device

Dry Powder Inhalers (DPI) Breath activated Micronized drug particles blended with an excipient (e.g., glucose or lactose) Physical properties of drug and excipient critical (i.e., particle size, shape, surface morphology, etc)

Diskus

Nebulizer Device produces small droplets from a suspension or solution through an air jet or ultrasonic atomization (quieter, but more expensive)

Topical Mucosal membranes (eye drops, antiseptic, sunscreen, callous removal, nasal, etc.) Skin a. Dermal - rubbing in of oil or ointment (local action) b. Transdermal - absorption of drug through skin (systemic action) i. stable blood levels ii. no first pass metabolism iii. drug must be potent or patch becomes to large

The skin is generally described in terms of three tissue layers: stratum corneum epidermis dermis subcutaneous fatty tissue

Dosage forms suitable for skin/transdermal route. cream and ointment transdermal patch e.g. scopolamine trsansdermal patch

Factors that influence percutaneous absorption Site of application Condition of skin Hydration of skin Temperature Vehicle

B. Ocular local action systemic action The cornea of the eye has one of the highest nerve densities in the human body, as a result patients perceive pain and discomfort even at low thresholds of stimulation. From: Fundamentals of Nursing, 4th edition, Lippincoitt, Williams & Wilkins

Types of Ophthalmic Preparations Solutions Suspensions Ointments Inserts Intraocular solutions

Factors that influence ocular drug retention Technique of application

Factors that influence ocular drug retention Technique of application Drop size (volume) Formulation (tonicity, viscosity) pH of solution

Route for administration -Time until effect- intravenous 30-60 seconds intraosseous 30-60 seconds endotracheal 2-3 minutes inhalation 2-3 minutes sublingual 3-5 minutes intramuscular 10-20 minutes subcutaneous 15-30 minutes rectal 5-30 minutes ingestion 30-90 minutes transdermal (topical) variable (minutes to hours)

$65.55 Which route is best? $143.11 $143.11 $41.71

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