routes of drug administration

ROUTES OF DRUG ADMINISTRATION

ADITHIYAN UDAYASANKAR

CONTENTS

O TYPES

O EXAMPLES

O FEW PICTURES

O ADVANTAGES

O DISADVANTAGES

O REFERENCE

DEFINITION OF DRUG

ODrug is any substance or

product that is used or is

intended to be used to

modify or explore

physiological systems or

pathological states for the

benefit of the recipient.

ROUTES OF ADMINISTRATION

OThe route of administration is

determined primarily by the properties

of the drug (for eg: water or lipid

solubility ,ionization) and by the

therapeutic objectives (eg: rapid onset

of action ,need for long term

treatment, or restriction of delivery to

a local site).

CLASSIFICATION OF ROUTES

LOCAL ACTION

SYSTEMIC ACTION

LOCAL ACTION

O Routes can be used for localized lesions

at accessible sites and for drugs whose

systemic absorption is minimal or absent.

O Thus high concentration are attained at

desired site without exposing the rest of

the body.

O E.g: glyceryl tri nitrate(GTN) applied on

the skin as ointment or transdermal patch.

TYPES

TOPICAL

DEEPER TISSUE

ARTERIAL SUPPLY

TOPICAL

O External application of the drug to the surface for localized action .

O It’s more convenient as well as encouraging to the patient.

O Drugs can be efficiently delivered to the localized lesions on skin, eyes, nasal mucosa in form of lotion, ointment, cream ,spray and lozengens.

O Clotrimazole is applied to skin in treatment of dermaphytosis.

DEEPER TISSUE

OCertain deep areas can be

approached by using a syringe and

needle , but the drug should be in a

form that systemic absorption is

slow.

OE.g: intra-articular injection i.e

hydrocortisone acetate in knee joint

, intrathecal injection ( lidocaine).

ARTERIAL SUPPLY

OIntra-arterial injection is used

for contrast media in

angiography .

OAnti cancer drugs can be

infused in femoral or brachial

artery to localise the effect for

limb malignancies.

SYSTEMIC ROUTES

The drug administered through systemic routes is intended to be absorbed into the blood stream and distributed all over, incl. the site of action.

Types

Systemic routes

oral

sublingual

Rectal

Cutaneous

Inhalation

Nasal

parenteral

ORAL

O Oldest and commonest mode of drug

administration.

O Solid dosage forms- powders , tablets,

capsules ,spansules .

O Liquid dosage forms – syrups, emulsions

and mixtures.

O 2 types

1. Enteric coated preparation

2. Extended release preparation

Enteric coated prepn.

OAn enteric coating is a

chemical envelope that

resists the action of the

fluids and enzymes in

stomach but dissolves in

u.i.t.

OE.g : omeprazole

Extended release prepn.

OExtended release medications have

special coatings or ingredients that

control how fast the drug is released

from the pill into the body.

OHaving a longer duration of action

may improve patient compliance

because the drug doesn’t have to

be taken often.

Oral-adv.&disadv.

Advantages

• Safest and most common , convenient, and economical route of administration

Disadvantages

• Limited absorption of some drugs.

• Food may affect absorption

• Drugs may be metabolized before systemic absorption

SUBLINGUAL

OTablet or pellet containing the

drug is placed under tongue or

crushed in the mouth and

spread over the buccal

mucosa.

ODrugs given sublingually are –

GTN, buprenorphrine ,

desamino-oxytocin.

S.L.-adv.&disadv.

Advantages

Bypasses first pass effect

Bypasses destruction by stomach acid

Disadvantages

Limited to certain types

of drugs

May lose part of the drug if swallowed

RECTAL

OCertain irritant & unpleasant

drugs can be put into rectum as

suppositories or retention

enema.

OE.g: diazepam ,indomethacin ,

paracetamol, ergotamine are

sometimes given rectally.

Rectal- adv.&disadv.

Advantages• Ideal if drug causes vomitting

• Ideal in patients who are comatose

Disadvantages• May irritate the rectal mucosa

• Not a well accepted route

INHALATION

OVolatile liquids and gases are given

by inhalation for systemic action.

OE.g: general anaesthetics and

coricosteroids such as fluticasone

OAbsorption takes place from the

vast of alveoli- action is very rapid.

Inhaln.-adv. & disadv.

Advantages

• Ideal for gases

• Dose can be titrated

• Fewer systemic side effects

Disadvantages

• Most addictive route

• Patient may have difficulty regulating dose

NASAL

OMucous membrane of the nose can readily absorb many drugs .

OE.g: desmopressin applied as a spray or nebulized solution have been used by this route.

ONasal decongestants such as oxymetazoline.

CUTANEOUS

O Highly lipid soluble can be applied over

the skin for slow and prolonged

absorption.

O The drug can be incorporated in an

ointment or in form of transdermal

therapeutic patches.

O Transdermal patches of GTN, fentanyl ,

nicotine and estradiol.

O TTS have designed to last for 1-3 days.

PARENTERAL

O It refers to administration by injection which takes the drug directly into the tissue fluid or blood without having to cross the enteral mucosa.

O Drug action is faster and surer .

O No gastric irritation or vommiting .

O Parenteral routes can be employed in unconsciousness , uncooperative .

O E.g: insulin injection

Parenteral- types

Par-beyond enteral-intestinal

Subcutaneous

Intramuscular

Intravenous

Intradermal injections

SUBCUTANEOUS

O The drug is deposited in the loose

connective tissue which is richly supplied

by nerves but is less vascular.

O 3 forms

1) Dermojet

2) Pellet implantation

3) Sialistic and biodegradable implants

Contd.O Dermojet : needle isn’t used. A high

velocity jet of drug soln. is projected from

a microfine orifice using a gun like

implement.

O Pellet implantation : drug is in the form of

a solid pellet is introduced with a trochar

and cannula. e.g: DOCA ,testosterone

O Sialistic & biodegradable implants:

crystalline drug is packed in tubes or

capsules made of suitable materials &

implanted under the skin. E.g; norplant

INTRAMUSCULAR

O The drug is injected in one of the large

skeletal muscles – deltoid , triceps

,gluteus maximus etc.

O E.g: Depot medroxyprogesterone,

haloperidol .

O Adv: suitable for oily vehicles and irritating

substances .

O Disadv: painful

Intra venous

OThe drug is injected as bolus or

infused slowly over hours in

one of the superficial veins.

OBioavailabity is 100%.

OMost common parenteral route

.

OE.g: sodium nitroprusside ,

atracurium

i.v- adv.& disadv.

Advantages

• Immediate effects

• Emergency situations

Disadvantages

• Bolus injection may result in adverse effects

• Strict aseptic techniques needed

INTRADERMAL

ODrug is injected into the

skin raising a bleb or

scarring puncture of the

epidermis through a drop of

the drug.

OE.g: BCG VACCINE,

sensitivity test.

REFERENCE