routes of administration

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Routes of Drug Administration : 

Routes of Drug Administration Dr.Reena verma Dept.of pharmacology

Routes of Drug Administration : 

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

Choice of routes : 

Choice of routes Physical & chemical properties of the drug Site of desired action Rate & extent of absorption of drug fm different routes Effect of digestive juices & first pass metabolism Rapidity of desired response- emergency or routine Accuracy of dosage Condition of the patient

First-pass Effect : 

First-pass Effect

classification : 

classification 1)Local - topical -deeper tissues -arterial 2)Systemic -Oral -Sublingual -Rectal -Cutaneous -Nasal -Inhalational -parenteral

local : 

local -for localized lesions at accessible sites -high concentration attained at desired site -systemic toxicity is low -can serve as systemic route of administration

topical : 

topical - external application to the surface. - Application on/to skin, oropharyngeal mucosa, nasal mucosa, eyes, ear canal, anal canal, vagina - Dosage forms- lotions, lozenges, ointment ,cream ,powder, paints, drops,sprays etc.

Deeper tissues : 

Deeper tissues Intra-articular injections Intrathecal Retrobulbar injections

arterial : 

arterial Contrast media in angiography Anticancer drugs for limb malignancies

Systemic routes : 

Systemic routes Drug is absorbed into blood stream to reach the site of action 1)oral- ADVANTAGES- safe, convenient, no assistance non invasive, painless, sterlization not required so cheaper. Dosage forms- solids -tablets, capules, GITs Liquids -syrups, elixirs, emulsions

Oral route cont. : 

Oral route cont. DISADVANTAGES- - slower onset of action - not for emergencies - unpalatable drugs cant be given, - nausea vomiting - cant be used in – uncooperative,unconscious,vomiting patient - absorbtion may be erratic or not possible, - some drugs may be destroyed by digestive juices or in liver

Sublingual route : 

Sublingual route Advantages - rapid absorbtion Action can be terminated Liver is bypassed Disadvantages-only Lipid soluble and nonirritating drugs can be given Examples-GTN,buprenorphine

rectal : 

rectal Examples - suppositories, retention enemas Advantages - in vomiting or unconscious patients Disadvantages- inconvenient embarrasing absorbtion -irregular,slow,unpredictable -Rectal inflammation -50% drug bypasses liver.

inhalation : 

inhalation Volatile liquids &gases given by inhalation Examples- general anaesthetics. Advantages-controlled administration- absorbtion-very rapid Termination of action-very fast

nasal : 

nasal Digestive juices &liver are bypassed Examples-GnRH agonists,desmopressin

cutaneous : 

cutaneous Application over the skin Advantages -slow & prolonged absorption, - liver bypassed TTS- transdermal therapeutic systems -structure -Site -Examples -Advantages,disadvantages

Parenteral : 

Parenteral Par-beyond , enteral -intestinal Advantages -faster ,surer -Nausea, vomiting not provoked -Can be used in- uncooperative ,unconscious patients -Food ,digestive juices and liver bypassed Disadvantages- -sterilized preparations so costly -Invasive, painful,requires assistance -risky

Parenteral routes : 

Parenteral routes Subcutaneous Intramuscular Intravenous intradermal

subcutaneous : 

subcutaneous Drug deposited in loose subcutaneous tissue(nerves) Less vascular-slow absorption than i.m -Self injection possible Repository preparation-longer action Other forms - dermojet, -pellets, -sialistic &biodegradable implants

intramuscular : 

intramuscular Site- deltoid ,triceps, gluteusmaximus,rectus femoris More vascular and less nerves Self injection-not possible Depot preparations can be used Avoid in anticoagulant treated patients

Intravascular : 

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 !@#$%

intravenous : 

intravenous Methods- a)bolus b)infusion Advantages - immediate effects, useful in emergencies - Irritant drugs can also be injected(may cause thrombophlebitis) - 100%bioavalaibilty, -large volumes can be infused -Titration of dose is possible Disadvantages-no depot preparations -risky.

intradermal : 

intradermal Injected in the skin by raising a bleb/multiple scarring Examples- skin testing, BCG vaccine

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 : 

Time-release preparations Oral - controlled-release, timed-release, sustained-release designed to produce slow,uniform absorption for 8 hours or longer better compliance, maintain effect over night, eliminate extreme peaks and troughs

Time-release preparations : 

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

Slide 28: 

The ROA 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 conc. at particular sites

Slide 29: 

No single method of drug administration is ideal for all drugs in all circumstances Very Important Info!

This was first stepjourney begins now : 

This was first stepjourney begins now