Routes of Drug Administration

Routes of Drug Administration
Factors Deciding Choice of
 Type of described effect, systemic or local
 Physiochemical properties, solid or insoluble
 Rapidity of effect
 Quality of effect
 Condition of patient, conscious or unconscious, vomiting
Drug Administration
Systemic Routes
Enteral through GIT
 Orally
 Buccal or sublingual
 Rectal
 Intravenous (IV)
 Intramuscular (IM)
 Subcutaneous (SC)
Enteral Route
Oral Administration
 Via mouth
 Tablets, capsules, powder, syrup, mixture suspension or
Advantages of oral route
 Convenience and patient comfort
 Safety, since medication can be retrieved in case of error or
intentional overdose
 Economy, since there are few equipment cost
Disadvantages of oral route
 Slower onset of absorption and action
 Rate and degree of absorption vary with gastrointestinal
contents and motility
 Some drugs destroyed by digestive fluids and must be
administered by injection
 Cannot be used with nausea or vomiting
 Dangerous to use if patient has dysphagia, due to the
possibility of aspiration
 Cannot be used for unconscious patients
 Cannot be use for patients who should keep nil by oral
Absorption from stomach and upper
intestine is affected by: Surface area
 Blood flow to site of absorption
 Physical state: solid, solution, suspension
 Water solubility
 Concentration at the site of absorption
 Rate of dissolution
 Rate of disintegration
 Particle size
Via Nasogastric tube/Gastric tube
 For the patients unable to swallow
 Advantages : ability to bypass mouth and pharynx when
necessary , elimination of numerous injections
 Disadvantages: discomfort specially for the conscious patients
Buccal or sublingual Route
 Buccal – medication placed in the pouch between the cheek
and the gum
 Sublingual – under the tongue
 Advantages: directly absorb to the circulation and rapid
 Disadvantage: misunderstanding of the way of use
Rectal Route
 For the patients having nausea and vomiting or patients who
are unable to swallow
 Advantages: bypassing the action of digestive enzymes
Avoidance of irritation to the upper GI tract
Disadvantages of Rectal route
 Many medications are unavailable in suppository form
 Prolonged use of rectal suppositories can cause rectal
 Absorption may be irregular or incomplete if feces are
 Inconvenient & embarrassing
 Rectal inflammation occurs
Parenteral Administration
Parenteral Administration
 Intravenous
 Intramuscular
 Subcutaneous
 Intradermal
 Intrathecal
 Intraarterial
 Intra articular
Intravenous Route
 Drug administration directly to the vein
 Direct injection
 Bolus
 Infusion
Advantages of Intravenous Route
 Immediate effects
 Valuable for emergency use
 Suitable for large volume
 Complete bioavailability
Disadvantages of Intravenous
 Not suitable for oily solutions & insoluble substances
 Drug administered cannot be withdrawn
 Thrombophlebitis occurs at injection site
 Lack of sterility may cause viral hepatitis
 Increased risk of adverse drug reactions
 Time and skill required for venipuncture
 Difficulty of maintaining IV line
 Complications of IV therapy – bleeding, infection and fluid
Intramuscular Route ( IM)
 Injections of drugs into certain muscles
 Usually doses 3ml or less
 IM injection
 Depot preparation
 Absorption depends upon rate of blood flow to the injection site
 Rapid action compared to SC route
 Slow releasing compared to IV route
 Advantages : can be use to administer solutions or suspensions
Slow, sustained effect from depot preparation
 Disadvantages: incorrect placement of the needle may damage
blood vessels or nerves
Abscess formation
Avoid during anticoagulant therapy
Subcutaneous Route (SC)
 Injection of drugs under the skin
 Use for highly soluble, non irritating, small volume of drug
about 1ml or less
 Absorption is slower and the drug action is generally longer
with SC injections than with IV or IM injections
 Advantages :Slow absorption and distribution
 Disadvantages: tissue damage, tissue necrosis and sterile abscess
Only nonirritant drugs
Not suitable for large volume
Intraarterial Route
 Direct injection into artery
 Localization of effect in particular tissue or organ
 Advantages: Diagnostics agents
 Disadvantages: Reserved route for experts
Intrathecal Route
 Injections into cerebrospinal fluid
 Blood Brain Barrier & Blood CSF Barrier slow drug entry
into CNS
 Used when local and rapid effects of drugs on the meninges
or cerebrospinal axis desired
Intradermal Route
 Injection into skin layers
Uses: BCG, Small pox vaccination
Testing drug sensitivity- Penicillin's
Tuberculin test
Intraarticular Route
 Drug administration directly to the joint
 Usually local effect
 Uses: Rheumatology disorders
Topical Application- Mucous
 Conjunctiva, nasopharynx, oropharynx, vagina, urethra,
urinary bladder, ear, nose, anal canal for local effects
 Ointment, cream, drops, jelly, powder, tablet, suppository,
pessary, sprays, gargles
Topical Application- Skin
 Absorption depends on surface area of application, lipid
 Few drugs readily penetrate skin
 Burned, denuded, abraded, inflammation increase systemic
 Controlled- release topical patches
 Advantages: Absorption rapid
Only local effect
 Disadvantages: Toxicity by highly lipid soluble substances
 Via inhaler
 Via nebulizer
 Medication directly to the respiratory system
Advantages of Inhalation
 Rapid action of the drug, with local effects with in the
respiratory tract
 Potent drugs may be given in small amounts, minimizing the
side effects
 Convenience and comfort of the patient
Disadvantages of Inhalation
 Requires cooperation of the patient in proper breathing
techniques for effectiveness
 Adverse systemic side effects may result rapidly because of
extensive absorption capacity of the lungs
 Improperly administered or too frequently administered,
inhalation can lead to irritation of the trachea or bronchi or
 If not clean properly nebulizers can be a source of infection
Thank you….
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