Drug Administration Routes Sublingual Intravenous Social Routes Source Of The Drug Pharmacology Introduction

General Pharmacology Introduction Routes Of Drug Administration

 

Question 1. Describe Routes Of Administration Of Drugs. Give Examples.
Or
Write Short Note On Routes Of The Drug Administration.
Answer:

Routes Of Administration Of Drugs

Routes can be broadly divided into Local routes and systemic routes.

1. Local Routes:

These routes can only be used for localized lesions.

• Topical: These are applied on the surface for localized action. It is applied on the skin or mucous membranes as ointment, cream, lotion, spray, etc. For example, tobramycin.
• Deeper tissues: Deeper tissues can be approached by using a syringe and needle, for example, intrathecal injection (Lignocaine).
• Arterial supply: Close intra-arterial injection is used, For Example, anti-cancer drugs can be infused in the femoral or brachial artery to localize the effect for limb malignancy.

Read And Learn More: Pharmacology Question And Answers

 2. Systemic Routes:

Drugs in these routes are absorbed into the blood and are distributed all over.

• Oral: This is the most common route. It is safer, more convenient, and cheaper. The presence of food in the stomach dilutes the drug and delays its absorption. For example, pantoprazole.
• Sublingual or buccal: The tablets or pellet containing the drug is placed under the tongue. Absorption is relatively rapid. Examples are nitroglycerine, isoprenaline, and clonidine.
• Rectal: Certain irritants and unpleasant drugs can be put into the rectum as suppositories. Examples are aminophylline, paraldehyde, and diazepam.
• Cutaneous: Highly lipid-soluble drugs can be applied over the skin for slow and prolonged absorption. These drugs are applied over the superficial area of the skin. For example, transdermal patches, i.e. thyroxin patches are given to prevent traveling sickness, nitroglycerine patches are used for emergencies in hypertension.
• Inhalation: Volatile liquids and gases are given by inhalation for systemic action. Absorption takes place from the vast surface of the alveoli. Action is very rapid. For example, asphalt for bronchial asthma.
• Nasal: The mucous membrane of the nose can readily absorb many drugs. Drugs in this route are applied as snuff or spray or nebulized solution. Examples, are drugs like insulin, and GnRH agonists.
• Parenteral: This refers to administration by injection which takes the drug directly into the blood or tissue fluid. Action is faster and surer.
• The important parenteral routes are:
  • Subcutaneous (SC): This is given just beneath the skin. For example, insulin injection.
  • Intramuscular (IM): The drug is injected into one of the large skeletal muscles. For example, diclofenac sodium.
  • Intravenous (IV): The drug is injected in one part of the superficial veins. For example, normal saline.
  • Intradermal injection: The drug is injected into the skin. Examples are the BCG vaccine and the smallpox vaccine.

 

Question 2. Write A Short Note On The Sublingual Route Of Administration.
Or
Write Short Note On The Sublingual Route Of Drug Administration.
Or
Write Short Note On Sublingual Drug Administration.
Or
Write Short Note On Sublingual Administration.
Answer:

Sublingual Administration

The tablet or pellet containing the drug is placed under the tongue or crushed in the mouth. The drug is sprayed over the buccal mucosa.

• Only lipid-soluble and non-irritating drugs can be administrated.
• Absorption is relatively rapid.
• The chief advantage is that the liver is bypassed. The drug is absorbed directly into the systemic circulation.
• The drugs given sublingually are nitroglycerine, isoprenaline, and clonidine.

Sublingual Administration Advantages

• The onset of action through this route is quick.
• As the tablet is removed from the mouth its action stops.
• This route bypasses first-pass metabolism.
• It is convenient for patients to use.

Sublingual Administration Disadvantages

• The route is not suitable for drugs having an intolerable taste.
• Lipid-soluble drugs and insoluble drugs should not be given through this route.

Question 3.  Description Of Intravenous Administration Of Drugs.
Or
Write A Short Note On The Intravenous Route Of The Drug Administration.
Answer:

Intravenous Administration

The drug is injected as a bolus or infused slowly over an hour in one of the superficial veins.

• The drug directly reaches the bloodstream and effects are produced immediately.
• The intima of veins is insensitive and the drug gets diluted with the blood, therefore even high irritant drugs can be injected intravenously.
• Only an aqueous solution can be injected intravenously.
• The dosage of the drug required is the smallest.
• Drug response is accurately measurable and short-acting.
• This is the most risky route. Vital organs like the heart, brain, and liver get exposed to high concentrations of the drug.
• Drugs through this route can be given in the form of a bolus, a slow intravenous injection, and an intravenous infusion.

Intravenous Administration Advantages

• The bioavailability of the drug is completely 100%.
• The onset of action is quick so the drug is used in an emergency.
• By this route, a large volume of fluid is administered.
• Via this route, highly irritating drugs can be given.
• Via this route, the hypertonic solution can be given.
• Through IV infusions, a constant plasma level of the drug is maintained.

Intravenous Administration Disadvantages

• Local irritation via this route can lead to phlebitis.
• Self-administration is not possible.
• An aseptic condition is necessary.
• If extravasation of the drug occurs this can lead to injury, necrosis, and sloughing of tissues.
• Depot preparation is restricted through this route.

Question 4. Describe The Advantages And Disadvantages Of Various Routes Of Drug Administration.
Answer:

Various Routes Of Drug Administration

Various routes of drug administration are:

 

 

Question 5. Describe The Social Routes Of The Drug Administration.
Answer:

Social Routes Of Drug Administration

Routes can be broadly divided into Local routes and systemic routes.

1. Local Routes:

These routes can only be used for localized lesions.

• Topical: These are applied on the surface for localized action. It is applied on the skin or mucous membranes as ointment, cream, lotion, spray, etc. For example, tobramycin.
• Deeper tissues: Deeper tissues can be approached by using a syringe and needle, for example, intrathecal injection (Lignocaine).
• Arterial supply: Close intra-arterial injection is used, For Example, anti-cancer drugs can be infused in the femoral or brachial artery to localize the effect for limb malignancy.

2. Systemic Routes:

Drugs in these routes are absorbed into the blood and are distributed all over.

• Oral: This is the most common route. It is safer, more convenient, and cheaper. The presence of food in the stomach dilutes the drug and delays its absorption. For example, pantoprazole.
• Sublingual or buccal: The tablets or pellet containing the drug is placed under the tongue. Absorption is relatively rapid. Examples are nitroglycerine, isoprenaline, and clonidine.
• Rectal: Certain irritants and unpleasant drugs can be put into the rectum as suppositories. Examples are aminophylline, paraldehyde, and diazepam.
• Cutaneous: Highly lipid-soluble drugs can be applied over the skin for slow and prolonged absorption. These drugs are applied over the superficial area of the skin. For example, transdermal patches, i.e. thyroxin patches are given to prevent traveling sickness, nitroglycerine patches are used for emergencies in hypertension.
• Inhalation: Volatile liquids and gases are given by inhalation for systemic action. Absorption takes place from the vast surface of the alveoli. Action is very rapid. For example, asphalt for bronchial asthma.
• Nasal: The mucous membrane of the nose can readily absorb many drugs. Drugs in this route are applied as snuff or spray or nebulized solution. Examples, are drugs like insulin, and GnRH agonists.
• Parenteral: This refers to administration by injection which takes the drug directly into the blood or tissue fluid. Action is faster and surer.
• The important parenteral routes are:
  • Subcutaneous (SC): This is given just beneath the skin. For example, insulin injection.
  • Intramuscular (IM): The drug is injected into one of the large skeletal muscles. For example, diclofenac sodium.
  • Intravenous (IV): The drug is injected in one part of the superficial veins. For example, normal saline.
  • Intradermal injection: The drug is injected into the skin. Examples are the BCG vaccine and the smallpox vaccine.

 

Question 6. Give A Brief Account On The Source Of The Drug.
Answer:

Source Of The Drug

Drugs are obtained from many sources:

• Animal source: Some drugs like insulin are obtained from the pancreas of beef or pork. Thyroid powder is obtained from the thyroid gland and some vaccines are also obtained from animal sources.
• Plant source: Some drugs are obtained from plants like quinine from cinchona bark, digitalis from fox glove, and morphine from papaver foraminifera.
• Mineral source: Some drugs are obtained from minerals or their salts like ferrous sulfate, magnesium sulfate, and iodine.
• Microbial source: Some drugs are obtained from microorganisms (bacteria, yeast, fungi). The drugs are antibiotics.
• Synthetic drugs: Most of the drugs are prepared synthetically. Synthetic drugs are formed by modifying the structure of normally occurring drugs.
• Genetic engineering: Some drugs like human insulin and human growth hormone are formed by using recombinant DNA technology.

Question 7. Write A Short Note On The Oral Route Of The Drug Administration.
Answer:

Oral Route Of The Drug Administration

This is the most common route. It is safer, more convenient, and cheaper. The presence of food in the stomach dilutes the drug and delays its absorption. For example, pantoprazole.

Oral Route Of The Drug Administration Advantages

• It is safe
• It is cheap and painless
• It is used easily for repeated and long-term use.
• It is self-administered by the user.

Oral Route Of The Drug Administration Disadvantages

This route is not recommended for:

• Unpalatable and high-irritant drugs
• For unabsorbable drugs
• For drugs destroyed by digestive juices
• In drugs that have high first-pass metabolism
• In the uncooperative and unconscious patients
• In patients with severe vomiting and diarrhea.

In cases of emergency, this route is not used.

Question 8. Write A Short Note On Transdermal Drug Delivery System.
Answer:

Transdermal Drug Delivery System

Transdermal patches are devices in the form of adhesive patches of various shapes and sizes which deliver the contained drug at a constant rate into systemic circulation via the stratum corneum.

• The drug is held in a reservoir between an occlusive backing film and a rate-controlling micropore membrane, the undersurface of which is smeared with an adhesive impregnated with a priming dose of the drug.
• The adhesive layer is protected by another film that is to be peeled off just before application.
• The drug is delivered at the skin surface by diffusion for percutaneous absorption into circulation.
• The micropore membrane is such that rate of drug delivery to the skin surface is less than the slowest rate of absorption from the skin.
• The drug is delivered at a constant and predictable rate irrespective of the site of application: usually, the chest, abdomen, upper arm, lower back, buttocks, or mastoid region are utilized.

Transdermal Drug Delivery System Advantages

• Self-administration is very easy.
• Better patient compliance.
• Prolonged duration of action.
• Systemic side effects get decreased.
• First-pass metabolism is bypassed.

Transdermal Drug Delivery System Disadvantages

• It is costly.
• Local irritation can lead to dermatitis and itching.
• It can go unnoticed by the patient.

Question 9. Write Short Note On Essential Drugs.
Answer:

Essential Drugs

WHO has defined essential drugs as those that satisfy the priority healthcare needs of the population.

They are selected with due regard to public health relevance, evidence on efficacy and safety, and comparative cost-effectiveness.

• WHO published its first model of an essential drug list in 1977.
• Essential drugs are supposed to be available in the hospital for the proper functioning of the basic health care system at all times, in adequate amounts. Inappropriate dosage forms, with assured quality and at a price affordable to the individual and community.
• It is expected that all countries should prepare their own essential drugs according to their own requirement because particular drugs may be
  essential to one country but may not be necessary to another country. For example, New Zealand is snake free country so anti-snake venom may not be an essential drug but it is essential for countries like India, Pakistan, and Bangladesh.
• It has been realized that only a handful of drugs out of the multitude available can meet the healthcare needs of the majority of people. In any country, many well-tested and cheaper drugs are equally (or more) efficacious and safe as their newer more expensive congeners.
• For optimum utilization of resources, governments (especially in developing countries) should concentrate on these drugs by identifying them as essential drugs.

Criteria For Selection Of Essential Drugs

The criteria for the selection of an essential medicine are as follows:

• Adequate data on its efficacy and safety should be available
  from clinical studies.
• It should be available in a form in which quality, including bioavailability, and stability on storage can be assured.
• Its choices should depend on upon pattern of prevalent diseases; availability of facilities and trained personnel; financial resources; genetic, demographic, and environmental factors.
• In the case of two or more similar medicines, the choice should be made on the basis of their relative efficacy, safety, quality, price, and availability. The cost-benefit ratio should be a major consideration.
• The choice may also be influenced by comparative pharmacokinetic properties and local facilities for manufacture and storage.
• Most essential medicines should be single compounds. Fixed ratio combination products should be included only. when the combination has a proven advantage in a therapeutic effect, safety, adherence, or in decreasing the emergence of drug resistance.
• The selection of essential medicines should be a continuous process that should take into account the changing priorities for public health action. Epidemiological conditions as well as the availability of better medicines/ formulations and progress in pharmacological knowledge.
• Recently, it has been emphasized to select essential medicines based on rationally developed treatment guidelines. Currently, it is the 18th Model List of Essential Medicines, prepared by the WHO Expert Committee in April 2013.

Question 10. Describe Briefl Various Branches Of Pharmacology.
Answer:

Various Branches Of Pharmacology

The following are the branches of pharmacology:

• Pharmacokinetics: It is the branch that deals with the movement of drugs and the alteration of drugs by the body. It includes the absorption, distribution, metabolism, and excretion of drugs. It deals with what the body does to the drug.
• Pharmacodynamics: This branch consists of the physiological and biochemical effects of drug and their mechanism of action on an organ at cellular. Subcellular and systemic levels. It deals with what the drug does to the body.
• Pharmacotherapeutics:  This branch is the application of pharmacological information together with knowledge of disease for its prevention, mitigation, or cure. The most specific part of pharmacotherapeutics is the selection of the most appropriate drug, its dosage, and treatment as per the features of the patient.
• Clinical pharmacology: This is the study of drugs in man. It consists of pharmacodynamics and pharmacokinetic investigation in healthy subjects and patients; evaluation of the efficacy and safety of drugs. Comparative trials with other different forms of treatment; surveillance of patterns of drug use, adverse effects, etc. This branch generates the data for the optimal use of drugs and to practice medicine that is evidence-based.
• Chemotherapy: This is the branch that deals with the treatment of systemic infections or malignancy with drugs that have selective toxicity for infecting organisms or malignant cells with minimal toxicity to host cells.
• Pharmacy: This is the art and science of compounding as well as dispensing drugs or preparing suitable dosage forms for the administration of drugs to man or animals. It consists of the collection, identification, purification, isolation, synthesis, standardization, and quality control of medicinal substances.
• Toxicology: This branch deals with the poisonous effects of drugs and other chemicals with an emphasis on the detection, prevention, and treatment of poisoning.
• Pharmacogenomics: This branch deals with the relationship of an individual’s genetic makeup with his or her response to a drug.
• Pharmacognosy: This branch deals with the study of sources and identification of drugs from plants.
• Biopharmaceutics: This branch deals with the development of new drug delivery systems and new dosage forms.

Question 11. Write A Short Note On The Inhalation Route Of The Drug Administration.
Answer:

Inhalation Route Of The Drug Administration

By inhalation route of drug administration volatile liquids and gases are given for systemic action.

•  A good example is a general anesthetic, i.e. nitrous oxide, which is given by inhalational route.
• Here absorption takes place from the vast surface of alveoli due to which action is very rapid.
• As the administration gets discontinued via the inhalational route, the drug diffuses back and is rapidly eliminated in expired air. So controlled administration is possible with moment-to-moment adjustment.

Inhalation Route Of The Drug Administration Advantages

• Its onset of action is quick.
• Systemic toxicity gets minimized as the dose given is very less.
• Regulation of the amount of drug given can be done.

Inhalation Route Of The Drug Administration Disadvantage

• Due to local irritation, there is increased respiratory secretion
• and bronchospasm.

Question 12. Classify Various Routes Of Drug Administration With Suitable Examples. Describe The Advantages And Disadvantages Of The Oral Route.
Answer:

Various Routes Of Drug Administration

Classification of Various Routes of the Drug Administration

1. Local route

• Topical
• Deeper tissue, i.e. intrathecal, intraarticular, retrobulbar injection
• Arterial supply, i.e. intra-arterial

2. Systemic route

• Oral route
• Sublingual or buccal route
• Rectal route
• Cutaneous, i.e. transdermal patches
• Inhalational
• Nasal
• Parenteral
  • Subcutaneous (SC)
  • Intramuscular (IM)
  • Intravenous (IV)
  • Intradermal.

Examples Of Various Routes

 

Advantages Of Oral Route

• It is safe
• It is cheap and painless
• It is used easily for repeated and long-term use
• It is self-administered by the user.

Disadvantages Of Oral Route

• This route is not recommended for:
  • Unpalatable and high-irritant drugs are difficult to administer; drugs may be filled in capsules to circumvent this
  • For unabsorbable drugs. Absorption of some drugs is erratic
  • For drugs destroyed by digestive juices, so their absorption cannot take place
  • Drugs having high first-pass metabolism in the liver get destroyed
  • In the uncooperative and unconscious patients
  • In patients with severe vomiting and diarrhea.
•  In cases of emergency this route is not used as action by this route is slower.

Question 13. Write A Long Answer On Routes Of The Drug Administration, Suitable For Emergency Situations.
Answer:

Routes Of The Drug Administration Suitable For Emergency Situations

Parenteral routes of drug administration are suitable for emergency situations.

This refers to administration by injection which takes the drug directly into the blood or tissue fluid.

Drug action is faster and surer and is valuable in emergencies. The important parenteral routes are:

• Intravenous (IV): Via this, the drug is injected as a bolus or infused slowly over hours in one of the superficial veins. The drug directly reaches the bloodstream and effects are produced immediately. It has great value in an emergency.
  Intima of veins is insensitive and the drug gets diluted with the blood, therefore, even highly irritant drugs can be injected I V.
  But hazards of this route are thrombophlebitis of the injected vein and necrosis of adjoining tissues if extravasation occurs.
  These complications should be minimized by diluting the drug or injecting it into a running IV line.
  Only aqueous solutions (not suspensions) can be injected IV and there are no depot preparations for this route. The dose of the drug required is smallest and even large volumes can be infused.
  One big advantage of this route is that if in case the response is accurately measurable and the drug is short-acting, titration of the dose with the response is possible.
  However, this is the riskiest route—vital organs like the heart, brain, etc. get exposed to high concentrations of the drug. The possibility of causing air embolism is another risk.
• Subcutaneous (SC ): In this route, the drug is deposited inside the loose subcutaneous tissue which is richly supplied by nerves but is less vascular (absorption is slower).
  Self-injection can be given because deep penetration is not needed. This route is avoided in shock patients who are vasoconstriction because in them absorption will be delayed.
  Repository (depot) preparations—oily solutions or aqueous suspensions can be injected for their prolonged action.
  Some special forms of this route are dermojet, pellet implantation, and dualistic as well as biodegradable implants.
• Intramuscular (IM ): In this drug should be injected in one of the large skeletal muscles such as the deltoid, triceps, gluteus maximus, rectus femoris, etc.
  Muscle is less richly supplied with sensory nerves and is more vascular. It is less painful, but self-injection should not be indicated as deep penetration is needed.
  Depot preparations can be injected by this route. Intramuscular injection should be avoided in patients taking anticoagulant medication.
•  Intradermal injection: The drug is injected into the skin raising a bleb (For example. BCG vaccine, sensitivity testing) or scarring/multiple punctures of the epidermis through a drop of the drug is done.
  This route is employed for specific purposes only.