1. SMARTTEACHING - PHARMACOLOGY: Introduction to Pharmacology:
Pharmacokinetics
Pharmacokinetics is the study of the way the body deals with any drugs that are given to it - “what the body does to a drug”.
Pharmacokinetics is a study of the processes of
absorption,
distribution, and
elimination,
either by metabolism or excretion, of drugs.
Routes of Drug Administration
Prof J Pieter H van Wyk

2. Major Routes of Drug Administration
INDEX
Introduction
Major Routes of Drug Administration
Other Routes of Drug Administration
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3. INTRODUCTION
Drug Administration
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4. Drug Therapy has at aim to
Prevent,
Cure or
Control
Disease Conditions to such an extent that Therapeutic and Nontoxic Levels are achieved at the
Target Tissues.
Drug Administration
Drug Therapy
Drug Toxicity
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5. speed of onset of drug action,
Drug Administration
The
speed of onset of drug action,
intensity of drug’s effect
duration of drug action
are controlled by four pathways of drug movement and modification in the body as illustrated by the diagram.
Drugs at site of administration:
First Pathway - Absorption.
Drugs are absorbed from site of administration into plasma.
Absorption
Drugs in Plasma:
Second Pathway - Distribution.
Drugs distribute reversible from bloodstream into interstitial and intracellular fluids.
Distribution
Drugs in Tissues:
Metabolism
Third Pathway - Metabolism.
Drugs metabolized by liver, tissue and other tissues.
Metabolites in Tissues:
Elimination
Fourth Pathway - Elimination.
Drugs removed from body in urine, bile or faeces.
Drug and or metabolites in urine, bile or faeces.
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6. MAJOR ROUTES OF DRUG ADMINISTRATION
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7. Therapeutic objectives.
Drug Administration
The route of drug administration is determined by properties of the drug such as:
Water solubility
Lipid solubility
(Water insoluble)
and
Therapeutic objectives.
Routes
Enteral and Parenteral are the two major routes of drug administration.
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8. swallowed - allowing oral delivery
Drug Administration
Enteral Administration:
Routes
Refers to the administration of a drug by the mouth which is the most simplest and most common route of administering a drug.
The drug can be:
swallowed - allowing oral delivery
placed under the tongue – allows direct absorption into the bloodstream.
Enteral
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9. Enteral Administration:
Drug Administration
Enteral Administration:
Oral Route
Routes
Advantages:
Oral drugs are easily self-administered
Limit systemic infections that could complicate treatment
Toxicities or overdose can be overcome with antidotes such as activated (powdered) charcoal.
Disadvantages:
Oral drugs are exposed to gastrointestinal (GI) environments which may limit its absorption
Most drugs are absorbed from the duodenum with its larger absorptive surface and enter the portal circulation where the drugs are exposed to a high extent of first-pass metabolism in the liver before entering the systemic circulation.
These drugs have to be given in sufficient quantities to ensure that enough reaches the target organ.
Enteral
Advantages
Disadvantages
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10. Enteral Administration:
Drug Administration
Enteral Administration:
Sublingual Route
Routes
Placement under the tongue allows the drug to diffuse into the capillary network and thus enter the systemic circulation directly.
Advantages:
Rapid absorption
Convenience of administration
Low incidence of infection
Avoidance of the harsh GI-environment
Avoidance of first-pass metabolism.
Sublingual
Advantages
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11. Parenteral Administration:
Drug Administration
Parenteral Administration:
Drugs are introduced directly into the systemic circulation and this procedure of administration is used for drugs that are poorly absorbed from the GI-tract and drugs that are unstable in the GI-tract.
Also used for:
Treatment of unconscious patients.
Circumstances that require rapid onset of action.
Advantages:
Exhibits the highest bioavailability of drugs.
Drugs are not exposed to first-pass metabolism or GI-conditions.
Provides most control over the actual dose of drug delivered to the body.
Routes
Parenteral
Advantages
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12. Parenteral Administration:
Drug Administration
Parenteral Administration:
Routes
Parenteral routes are:
irreversible
may cause pain
may cause fear
may cause infection.
Parenteral routes of drug administration are classified as:
intravascular
intramuscular
subcutaneous.
Parenteral
p 37
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13. Parenteral Administration:
Drug Administration
Parenteral Administration:
Intravenous (IV)
Routes
Most common parenteral route and used for drugs that are not absorbed orally.
Advantages and disadvantages:
Drugs avoid the GI-tract and first pass metabolism in the liver.
Rapid effect of the drug and maximum control over drug is achieved.
Drugs cannot be recalled by binding to activated charcoal.
Bacteria can be introduced at site of administration.
May induce haemolysis.
Adverse reactions could be caused by the too-rapid delivery of high concentrations of a drug to the plasma or tissue.
Intravenous (IV)
Advantages
Disadvantages
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14. Parenteral Administration:
Drug Administration
Parenteral Administration:
Intramuscular (IM)
Routes
An intramuscular (IM) injection is the preferred route of administering medication when fairly rapid-acting and long-lasting dosage of medication is required.
Some medications that are irritating to the subcutaneous tissue may be given into the deep muscle tissue.
Injection of medication into muscle tissue forms a deposit of medication that is absorbed gradually into the bloodstream.
An intramuscular injection is safe, easy, and well tolerated.
Intramuscular (IV)
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15. Parenteral Administration:
Drug Administration
Parenteral Administration:
Subcutaneous (SC)
Routes
This route (a needle is inserted just under the skin and the drug can then be delivered into the subcutaneous tissues) requires the absorption and is slower than the IV-route.
It minimizes the risks associated with intravascular injections.
Examples:
single rod containing the contraceptive etonogestrel for long term activity.
programmable mechanical pumps to deliver insulin in diabetic patients.
Subcutaneously (IV)
p 24
p 25
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16. OTHER ROUTES OF DRUG ADMINISTRATION
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17. Inhalation: Examples:
Drug Administration
Inhalation:
Results in a rapid delivery of the drug across the large surface area of the mucous membranes of the respiratory tract and pulmonary epithelium.
The effect of a drug is almost as rapid as with IV-injections.
This route used for drugs that are gases or dispersed in an aerosol.
The route is effective for patients with respiratory complains (asthma) as the drug is delivered at the site of action and systemic effects are minimized.
Examples:
Salbutamol - used to treat or prevent bronchospasm in people with reversible obstructive airway disease.
Corticosteroids such as fluticasone.
Routes
Inhalation
p 26
p 27
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18. Intranasal: Examples:
Drug Administration
Intranasal:
Drug is administered directly into the nose.
Examples:
Anti-inflammatory corticosteroid such as mometasone furoate.
Desmopressin in treatment of diabetes insipidus.
Calcitonin a peptide hormone used in treatment of osteoporosis.
Abused drug cocaine is taken by intranasal sniffing.
Routes
Intranasal
p 28
p 29
p 30
p 31
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19. Intrathecal / Intraventricular:
Drug Administration
Intrathecal / Intraventricular:
Routes
Direct transfer of drugs in the cerebrospinal fluid.
Example:
Amphotericin B used in the treatment of Cryptococci meningitis.
Intrathecal
Intraventricular
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20. This route is followed when a local effect of the drug is desired.
Drug Administration
Topical:
Routes
This route is followed when a local effect of the drug is desired.
Examples:
Clotrimazole is applied as a cream in the treatment of dermatophytosis.
Tropic amide or cyclopentolate are administered drop by drop into the eye to dilate the pupil and allow measurement of refractive errors.
Topical
p 32
p 33
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21. Drug Administration
Transdermal:
Routes
Application of the drug to the skin by means of a transdermal patch and this route of drug administration achieves systemic effects.
The rate of drug adsorption is determined by the physical properties of the skin at the position of application.
This route is used for the sustained delivery of a drug.
Examples:
Antianginal drug, nitroglycerine.
Antiemetic drug, scopolamine.
Once a week contraceptive patch, ortho evra.
Transdermal
p 34
p 35
p 36
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22. Advantages and disadvantages:
Drug Administration
Rectal:
Routes
Fifty percent of the drainage of the rectal region bypasses the portal circulation.
Advantages and disadvantages:
Bioconversion of drugs by the liver is minimized.
Preventing the destruction of the drug by intestinal enzymes or low pH of the stomach.
Useful if drug induces vomiting when given orally.
Rectal absorption could be erratic and incomplete and many drugs irritate the rectal mucosa.
Rectal
Advantages
Disadvantages
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23. Routes of Drug Administration
Pharmacokinetics -
Routes of Drug Administration
END
Next Topic:
Absorption of Drugs.

24. Etonogestrel implant is used as contraception to prevent pregnancy.
The medicine is contained in a small plastic rod that is implanted into the skin of the upper arm.
The medicine is released slowly into the body.
The rod can remain in place and provide continuous contraception for up to 3 years.

25. Insulin is a natural hormone made by the pancreas that controls the level of the sugar glucose in the blood.
Insulin permits cells to use glucose for energy. Cells cannot utilize glucose without insulin.
Diabetes: The failure to make insulin or to respond to it constitutes diabetes.
Insulin is made specifically by the beta cells in the islets of Langerhans in the pancreas.
If the beta cells degenerate so the body cannot make enough insulin on its own, type I diabetes results.
A person with this type of diabetes must inject exogenous insulin (insulin from sources outside the body).
In type II diabetes, the beta cells produce insulin, but cells throughout the body do not respond normally to it.
Nevertheless, insulin also may be used in type II diabetes to help overcome the resistance of cells to insulin.
By reducing the concentration of glucose in the blood, insulin is thought to prevent or reduce the long-term complications of diabetes, including damage to the blood vessels, eyes, kidneys, and nerves.

26. Salbutamol is also used to prevent exercise-induced bronchospasm.
Salbutamol is a bronchodilator that relaxes muscles in the airways and increases air flow to the lungs.
Salbutamol is used to treat or prevent bronchospasm in people with reversible obstructive airway disease.
Salbutamol is also used to prevent exercise-induced bronchospasm.

27. Fluticasone is used to prevent and relieve allergy of the inside of the nose; commonly caused by hay fever and other allergies. It can also be used to treat nasal polyps which are small lumps found inside the nose.
Dryness and irritation of the nose and throat, mild nose bleeds or disturbance of taste and smell and headache are the most common side effects.

28. Mometasone furoate is a synthetic (man-made) steroid hormone in the glucocorticoid family of steroid hormones that is used for the treatment of nasal allergy.
The naturally occurring glucocorticoid hormone is cortisol or hydrocortisone which is produced in the adrenal glands.
Glucocorticoid hormones are potent reducers of inflammation (anti-inflammatory).
When used as a nasal inhaler or spray, medications go directly to the inner lining of the nose, and very little is absorbed into the body.

29. Desmopressin is used to control the amount of urine kidneys produce.
Normally, the amount of urine produced is controlled by a certain substance in the body called vasopressin.
Desmopressin is a man-made form of vasopressin and is used to replace a low level of vasopressin.
This medication helps to control increased thirst and too much urination due to these conditions, and helps prevent dehydration.

30. In humans, calcitonin is produced by the thyroid gland.
Calcitonin-salmon is a man-made version of the hormone, calcitonin, used for treating postmenopausal (after menopause) osteoporosis (bone loss) and hypercalcemia (high blood calcium levels).
In humans, calcitonin is produced by the thyroid gland.
It acts primarily on bone that is in a constant state of remodelling, whereby old bone is removed by cells called osteoclasts, and new bone is laid down by cells called osteoblasts.
Calcitonin promotes bone formation.

31. Cocaine is a strong central nervous system stimulant that increases levels of dopamine, a brain chemical (or neurotransmitter) associated with pleasure and movement, in the brain’s reward circuit.
Cocaine acts by preventing the dopamine from being recycled, and this excess of dopamine is responsible for cocaine’s euphoric effects.
With repeated use, cocaine can cause long-term changes in the brain which may eventually lead to addiction.
Some users will increase their dose in an attempt to intensify and prolong the euphoria, but this can also increase the risk of adverse psychological or physiological effects.

32. Clotrimazole is an anti-fungal medication related to fluconazole (Diflucan), ketoconazole (Nizoral), itraconazole (Sporanox), and miconazole (Micatin, Monistat).
It prevents growth of several types of fungi by preventing production of the membranes that surround fungal cells.
It is used topically on the skin, inserted vaginally or allowed to dissolve in the mouth for local fungal infections.

33. Tropicamide blocks the receptors in the muscles of the eye (muscarinic receptors).
These receptors are involved controlling the pupil size and the shape of the lens.
By blocking these receptors, tropicamide produces dilatation of the pupil (mydriasis) and prevents the eye from accommodating for near vision (cycloplegia).
Tropicamide is given as eye drops to dilate the pupil and relax the lens so that eye examinations can be carried out thoroughly.

34. it can also be used as skin patches or sustained-release tablets.
Nitroglycerine:
causes the arteries in your body (including the coronary arteries) to widen -- this improves the blood flow to your heart.
can be given as a small tablet under the tongue or a spray under the tongue to work immediately.
it can also be used as skin patches or  sustained-release tablets.

35. an anticholinergic medicine.
Scopolamine:
an anticholinergic medicine.
decreases the secretion of fluids in stomach and intestines, and dilation of the pupils.
is used to relieve nausea, vomiting, and dizziness associated with motion sickness and recovery from anaesthesia and surgery.
may also be used in the treatment of parkinsonism.

36. Ortho Evra:
combination transdermal contraceptive containing 6.00 mg norelgestromin (NGMN) and 0.75 mg ethinyl estradiol (EE).

38. Pathways of Movement and Modification of a Drug in the Body
kNowNow:
By completing this presentation the student should be able to know and understand the following:
Aim of Drug Therapy
Pathways of Movement and Modification of a Drug in the Body
Major Routes of Drug Administration
Advantages and Disadvantages of the various Routes of Drug Administration
Examples of Drugs administered by the Various Routes.