ROUTE OF DRUG ADMINISTRATION ( Part 2/3 )

2) Parenteral Route of Drug Administration:

Parenteral route of Drug administration

• The parenteral route introduces drugs directly across the body’s barrier defenses into the systemic circulation. Parenteral administration is used for drugs that are
• Poorly absorbed from the gi tract (for example, heparin)
• Or that are unstable in the gi tract (for example, insulin).

Merits:

Parenteral route administration has following advantages.

• Parenteral administration is also used for treatment of unconscious patients and under circumstances that require a rapid onset of action.
• In addition, these routes have the highest bioavailability and are not subject to first-pass metabolism or harsh gi environments.
• Parenteral administration provides the most control over the actual dose of drug delivered to the body.

Demerits:

Parenteral route administration has following disadvantages.

• These administrations are irreversible.
• May cause pain, fear.
• Local tissue may damage.
• Parenteral preparation should be sterile otherwise maximum probability for infection because the drug is directly reached to the blood stream.

Types of Parenteral route: 

There are following parenteral routes.

A)Intravenous route (i/v)

B)Intramuscular route (i/m)

C)Subcutaneous route (s/c)

D)Intra peritoneal route (i/p)

C)Intra cardiac route (i/c)

A) Intravenous route (i/v) :

Intravenous route

 

• Iv injection is the most common parenteral route in which the drug is administered into the vein.
• Intravenous injections might be applied to the cubital, basilic and cephalic vein.

Merits:

• I/v injection is advantageous for administering chemicals that may cause irritation when administered via other routes, because the substance is rapidly diluted by the blood.
• I/v delivery permits a rapid effect and a maximum degree of control over the circulating levels of the drug.
• absorption is not required.
• This route is preferred in emergency situations.
• This route is preferred for unconscious patients.
• Large volume of fluids or blood plasma might be injected by this route.

Demerits:

• Iv injection may inadvertently introduce bacteria and other infective particles through contamination at the site of injection. So the preparation should be sterile.
•  it may also precipitate blood constituents, induce hemolysis.
• May cause other adverse reactions by the too-rapid delivery of high concentrations of a drug to the plasma and tissues.
•  therefore, patients must be carefully monitored for unfavorable drug reactions, and the rate of infusion must be carefully controlled.
• This method is not suitable for oily and insoluble preparations

B) intramuscular route:

intramuscular route

 

• Drugs administered im can be in aqueous solutions, which are absorbed rapidly.
• Or in specialized depot preparations, which are absorbed slowly,providing a sustained dose over an extended period of time.
• Intramuscular route might be applied to the buttock, thigh and deltoid.
• The volume used is 3 ml.

Merits:

• absorption is rapid than subcutaneous route and reasonably uniform.
• Rapid onset of action.
• Oily preparations can be used.
• Irritative substances might be given.
• Slow releasing drugs can be given by this route.

Demerits:

• Using this route might cause nerve or vein damage.
• Local pain and abscess.
• May cause infection.
• It’s expensive.

C) sub-cutaneous route (s/c) :

sub-cutaneous route

 

• This route of administration, like in injection, requires absorption via simple diffusion and is somewhat slower than the iv route.
• Subcutaneous route might be used for the arm, forearm, and thigh and sub scapular space.
• The volume used is 2 ml.
•  insoluble suspensions like insulin and solids might be applied by this route.
• Examples of drugs given by subcutaneous route include insulin, adrenaline etc

Merits:

• Sc injection minimizes the risks of hemolysis or thrombosis associated with iv injection.
• absorption is slow and provideconstant, slow and sustain effect.
• It is hygienic.

Demerits:

• This route should not be used with drugs that cause tissue irritation, because severe pain and necrosis may occur.
• It might lead to abscess formation.
• absorption is limited by blood flow.

D) intra peritoneal route (i/p) :

intra peritoneal route

 

• In this route, a drug is injected into the peritoneal cavity.
• Many different drugs have been administered i/p in peritoneal dialysis therapy, for local (e.g., antibiotics) and systemic (e.g., insulin) effects.
• The i/p route is the recommended route for administration of antibiotics in the treatment of peritonitis.
• By this, fluid like glucose and saline can also be given to children.
• I/p injection is generally preferred when large amounts of blood replacement fluids are needed, or when low blood pressure or other problems prevent the use of a suitable blood vessel for intravenous injection.

Merits:

• Rapid absorption because larger absorptive surface area than i/m / subcutaneous.
• Large volume of drug may be injected.
• A practical advantage of the i/p route is that it avoids vein puncture and can be safely done by the patient at home after appropriate training.
• Used frequently in lab animals.

Demerits:

• Not suitable for irritating compounds because it causes chemical peritonitis. 
• There is possibility of puncturing of intestine or other abdominal organs.
• Preparation of such fluids should be sterile.

E) intracardial route (ic) :

intracardial route

 

• Cardiac injection  drug is injected directly in to the heart.
• Examples of drugs given by intra cardial route include epinephrineetc

Merits:

• This route is just use in case of cardiac emergency.
• Very rapid absorption.
• Rapid onset of action.

Demerits:

• These administrations are irreversible.
• It’s  very expensive.
• Highly skilled person should administrated drug through this route.

TO BE CONTINUED....