ROUTES OF DRUG ADMINISTRATION
Drugs are administered according to the preparation of the drug and effect desired, physical and mental condition of client. The route of administration should be indicated when prescribe the medicine. The nurse should ensure that the pharmaceutical preparation is appropriate for the specified route.
The route of administration that is chosen may have a profound effect upon the speed and efficiency with which the drug acts
The Route of administration is determined by the physical characteristics of the drug, the speed which the drug is absorbed and/ or released, as well as the need to bypass hepatic metabolism and achieve high concentration at particular sites.
Enteral through GIT
· Buccal or sublingual
Parental: Par-way, enterm-intestine
· Intravenous (IV)
· Intramuscular (1M)
· Subcutaneous (SC)
Enteral – drug placed directly in the GI tract:
· sublingual – placed under the tongue
· Buccal:placed against the mucus membranes of the cheek.
· Oral –swallowing
1. Oral administration:
Oral administration is the most common, least expensive, easiest and safe method of drug administration and convenient for most patients.
· 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
· Can also be administered through feeding tubes
· 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
· Unpleasant taste of drugs
· Some drugs cause staining of teeth(ferrous sulphate, iron)
· Effect too slow for emergencies
· Unpleasant taste of some drugs
· Unable to use in unconscious patient
· Inappropriate when GI Tract has reduced mobility
· Cannot be used before certain diagnostic tests or surgical procedures
· Can be aspirated by seriously ill clients.
The first-pass effect is the term used for the hepatic metabolism of a pharmacological agent when it is absorbed from the gut and delivered to the liver via the portal circulation. The greater the first-pass effect, the less the agent will reach the systemic circulation when the agent is administered orally.
Drug is placed under the tongue, where it dissolves. In a relatively short time the drug is absorbed to blood stream under the tongue. (E.g. Nitro glycerides).
In buccal administration, the medication is held in mouth against the mucous membrane of cheek until it dissolves. The drug may act locally or systemically when it is swallowed in saliva. Alternate cheeks with subsequent dose.
Instruct – not to chew, swallow or take liquids.
· Rapid absorption
· Drug stability
· Avoid first-pass effect
· Small doses
· If swallowed may be inactivated by gastric juice
· Unpleasant taste of some drugs
In this method, the drug is introduced in to the body orifice. E.g . Suppositories
Medication in suppository form (small cylindrical, waxy base) may be placed in the rectum to treat systemic complaints or as a laxative to encourage bowel movements.
Liquid medications may be instilled in to the rectum using an enema to encourage bowel movements or to treat clients with elevated potassium levels.
· Can be used in unconscious patients and children and if patient is having nausea or vomiting
· Easy to terminate exposure
· Absorption may be variable
· Good for drugs affecting the bowel such as laxatives
· Irritating drugs contraindicated
· Can be used when drug has objectionable taste or odor
· Drug released at slow, steady rate
· May be perceived as unpleasant by the client
· Provides a local therapeutic effect
Administration of drug in form of powder, vapour, in to a wound or body cavity by blowing with an insufflators.
Implantation means planting or putting in of solid drugs in to the body tissues.
7. Topical application:
Topical applications are those applied to circumscribed surface area of the body.
· Dermatologic preparations.
· Instillation (fluid into a body cavity)-fluid is retained
· Irrigation (pouring a drug in liquid form in to a body cavity)-fluid is not retained
· Spraying medication into body cavity
Topical applications include
1. Dermatologic preparations: applied to the skin
a. Dermal – rubbing in of lotions, creams, oil or ointment to the skin
· Used to treat a skin or wound infection or skin disease or decrease symptoms of skin disorders
· Local effect
b. Transdermal – medications designed to be absorbed through the skin for systemic effects are called Transdermal medications. Usually prepared as patches. Allows controlled amount of medication to be supplied over 24-72 hrs.
· leaves oily substance on skin
· Soils clothes
2. Ophthalmic medications: Ophthalmic medications or ointments are administered to treat conditions of the eyes. Medications are instilled in to the lower conjunctival sac.
3. Otic medications: Medications may be instilled in to the ear to treat external ear infections or to soften and remove ear wax.
4. Nasal Medications: Solutions are usually sprayed or instilled in to the nose. Usually used to treat nasal congestion.
5. Vaginal medications: medications given vaginally comes in various forms: Jelly’s, liquids (douches) creams, tables or suppositories. Provide a local effect.
Disadvantages: May be messy and may soil clothes
May be used to induce anaesthesia or to treat respiratory conditions.
Inhaled medication may be administered through a hand held nebulizer, a metered or a mechanical ventilator
Liquid medications are added to a receptacle in the ventilator or nebulizer and changed in to a gas form when air or 02 flows over them.
Rapid onset of action due to rapid access to circulation
Drug can be administered to unconscious client
· Inserting a medication similar to contact lens into the patient’s eye.
· The eve medication disk has 2 soft outer layers that have medication enclosed in them.
· Nurse inserts disk into eye —remains there up to I week
8. Parentral administration
Parentral means administration of therapeutic agents outside the alimentary tract. (Parsbeside, enteron- intestine).
· Intra muscular (IM) – drug injected into skeletal muscle
· Intra venous (IV) – placing a drug directly into the blood stream
· Intradermal,under the epidermis, to the dermis.
· Intra-arterial –into artery
· Intra cardiac – in to the cardiac muscle
· Intra thecal or intra spinal – in to the spinal cavity
· Intraosseous –in to the bone marrow
· Intraperitonial (peritoneal cavity) – in to the peritoneal cavity.
· Subcutaneous –Absorption of drugs from the subcutaneous tissues
· Inhalation –Absorption through the lungs
· Epidural –in to the epidural space
· Intrapleural – in to the pleural space
· Intraarticular – into a joint
· Absorption phase is bypassed (100% bioavailability)
· precise, accurate and almost immediate onset of action,
· Large quantities can be given.
· Greater risk of adverse effects
· Limited to highly soluble drugs
· Drug distribution is inhibited by poor circulation.
· Risk of introducing infections
· rapid absorption of drugs
· can administer larger volumes than subcutaneous
· Pain at injection sites for certain drug
· Can produce anxiety
SUBCUTANEOUS (HYPODERMIC): the subcutaneous tissue, just below the skin
· Slow and constant absorption
· Absorption is limited by blood flow,
· Affected if circulatory problems exist
· More expensive than oral
· Slower than intramuscular administration
· Breaks skin barrier
· Can administer only small volume
· Some drugs can irritate tissues and cause pain can produce anxiety
Intradermal (ID) under the epidermis (into the dermis)
· Drug inj. into layers of skin
· Multiple puncture of epidermis
· BCG, Small pox vaccination
· Testing drug sensitivity
Small dose only can be given
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)