Routes of Drug AdministrationRoutes of Drug Administration

ROUTES

MAIN TYPES

ENTERAL PARENTERAL TOPICAL/LOCAL

ENTERAL

ORALEX.-CAPSULE

SYRUP POWDER

SUSPENSION

SUBLINGUALEX.-NEFEDIPIN

ISOSORBITENITROGLYCERIN

ISOPRENALIN

RECTALDULCOLAX

GLYCERIN SUSP.OINTMENT

ENEMA,DIZEPAM

PARENTERAL ROUTE

INTRAVENOUS-Ex.-Glucose, N.S., Dextrose, Heparin.

INTRAMUSCULAR- Ex. –oily solution, antibiotics, vaccines, neuroleptics.

INTRAPERITONEAL- Ex- Antirabies, peritoneal dialysis.

INTRATHECALINTRATHECAL-Ex –Xylocaine inj.

INTRAMEDULLARY-Ex. Bone marrow transplantations, blood transfusion in child.

INTRAATERIAL –Ex. Anticancer drugs, for coronary angiography.

INTRA-ARTICULAR- Ex. Hydrocortisone, gold inj.

SUBCUTANEOUS- Ex. L.A., insulin,vaccine.

INHALATION- Ex.-Oxygen, salbutamol.

INTRADERMAL – Ex. Test sensitivity, BCG vaccine.

TOPICAL/LOCAL ROUTE

TRASDERMAL-Ex. Patch-nitroglycerin, scopalamine, clonidine.

CONJUNTIVAL – ex. Oint, drop, eg-gentamycin,ciprofloxacin.

VAGINA, URETHRA- Ex. Solu, oint, jelly, pessaries, suppository.

INNCTION(Rubbing)-Ex. Antifungal oint , powder, liniment.

MUCOUS MEMBRANE – Ex. Gargals, lozenges, mouth wash.

Routes of Drug Administration

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

ImportantImportantInfoInfo

Factors affecting choice of route

Physical and chemical properties of drugs. Site of desired action Rate and extent of absorption of drug

from different routes. Effect of digestive juices and first pass

metabolism. Rapidity with which response is desired. Condition of patient. Accuracy of dosage required.

Routes Of Administration

Local Systemic

Topical Enteralparenteral

Skinmucous membrane

Deeper tissues intraarticular, intrathecal, retrobulbar

Arterialanticancerous drugs, angiography

Routes Of Administration

Systemic routes Of Drug Administration

EnteralParenteral

OralInjection RectalRespiratoryCutaneous

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

EnteralParenteral

Enteral Routes

Enteral - drug placed directly in the GI tract:sublingual - placed under the

tongueoral - swallowing (p.o., per os)rectum - Absorption through the

rectum

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

Sublingual/Buccal

Disadvantages inconvenient small doses unpleasant taste of some drug

Examples1. Nitroglycerine2. Isoprenaline3. clonidine

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

DisadvantagesSometimes inefficient - only part

of the drug may be absorbedFirst-pass effect - drugs

absorbed orally are initially transported to the liver via the portal vein

irritation to gastric mucosa - nausea and vomiting

Oral

Disadvantages cont.destruction of drugs by gastric

acid and digestive juiceseffect too slow for emergenciesunpleasant taste of some drugsunable to use in unconscious

patient

First-pass Effect 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

First-pass Effect

1. unconscious patients and children 2. if patient is nauseous or vomiting 3. easy to terminate exposure 4. absorption may be variable 5. good for drugs affecting the bowel such as laxatives6. irritating drugs contraindicated

Rectal

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

Inhalation - Absorption through the lungs

Routes of Drug Administrationcommon abbreviations…

PO = per os = oral

IV = intravenous = into the vein

IM = intramuscular = into the muscle

SC = subcutaneous = between the skin and muscle

IP = intraperitoneal = within the peritoneal cavity

icv = intracerebroventricular =directly into the ventricle of the brain

Oral Administration

Intestines

Liver

IntravenousAdministration

Metabolism

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 c. OOPS factor or !@#$%

Intramuscular

1. very rapid absorption of drugs in aqueous solution 2.repository and slow release preparations 3.pain at injection sites for certain drugs

Subcutaneous

1. slow and constant absorption 2. absorption is limited by blood flow, affected if circulatory problems exist 3. concurrent administration of

vasoconstrictor will slow absorption

Peridural Anesthesia

This is accomplished by injecting a local anesthetic into the peridural space, a covering of the spinal cord

Spinal anesthesia

Here, the local anesthetic is injected into the subarachnoid space of the spinal cord

1.gaseous and volatile agents and aerosols 2.rapid onset of action due to rapid access to circulation a.large surface area b.thin membranes separates alveoli from circulation c.high blood flowParticles larger than 20 micron and the particles impact in the mouth and throat. Smaller than 0.5 micron and they aren't retained.

Inhalation

Inhalation cont.

Respiratory system. Except for IN, risk hypoxia.

Intranasal (snorting) Snuff, cocaine may be partly oral via post-

nasal dripping.

Smoke (Solids in air suspension, vapors) absorbed across lung

alveoli: Nicotine, opium

Volatile gases: Some anaesthetics (nitrous oxide, ether)

petroleum distillates. Diffusion and exhalation (alcohol).

Lung-based transfer may get drug to brain in as little as five

seconds.

Topical

Skin a. Dermal-rubbing in of oil or ointment

(local action), paste, powder, cream, dressing, spray, etc

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

Mouth and pharynx- paints, lozynges, mouthwash, gargles.

Eyes, ear, nose- drops, ointments, irrigation, spray.

Git- nonabsorable drugs given orally.

Bronchi and lungs- inhalations,aerosols.

Urethra- ` jellys

vagina- Peseries, vaginal tablets,cream,powder.

Anal canal- ointments.

Mucosal membranes

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)

Route for administration -Time until effect-

Time-release preparations

Oral - controlled-release, timed-release, sustained-release designed to produce slow,uniform

absorption for 8 hours or longerbetter compliance, maintain effect

over night, eliminate extreme peaks and troughs

Time-release preparations

Depot or reservoir preparations - parental administration (except IV), may be prolonged by using insoluble salts or suspensions in non-aqueous vehicles.

The ROA is determined by the The ROA is determined by the physical characteristics of the physical characteristics of the drug, the speed which the drug is drug, the speed which the drug is absorbed and/ or released, as well absorbed and/ or released, as well as the need to bypass hepatic as the need to bypass hepatic metabolism and achieve high metabolism and achieve high conc. at particular sitesconc. at particular sites

ImportantImportantInfoInfo

No No singlesingle method of drug method of drug administration is ideal for all administration is ideal for all drugs in all circumstancesdrugs in all circumstances

Very Important

Very Important

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