DRUG
•Any chemical that affects the processes of a living organism.
PHARMACOLOGY
•The study or science of drugs.
TWO CONCERNS ON PHARMACOTHERAPEUTICS:
*drug effects on the body
**the body's response to the drug
ORIGIN and the DIFFERENT SOURCES of the DRUGS
Common sources:
1. PLANT SOURCES
...root, bark, leaves, flowers and seeds of plant
...from medicinal plants that can be use as a drug component
*Properties:
> alkaloid (bitter)
= alkaline in reaction; physiologically power in activity
> glycoside
= compound containing carbohydrate molecule
> resins
= chief source in pine tree sap commonly acts as laxatives
> gum
= used in skin preparations as a soothing effect like the Karaya gum
= also used as a bulk laxative (for massive evacuation)
>oil
= classified as fixed oil (oil that does not evaporate in warming
= occurs in solid or liquid form (e.g. Castor oil) and volatile oil (evaporates readily and occurs in aromatic plants (e.g. peppermint)
2. ANIMAL SOURCES
...processed from an organ, from organ secretion or from organ cells (e.g. insulin which is derived from pancreas of sheep, cattle and hogs)
3. MINERAL SOURCES
...inorganic elements occurring in nature but not of plants or animal origin
...it's from a base or acid salt in food
4. SYNTHETIC SOURCES
...most common
...pure drug made in a laboratory from chemical, not natural substance (e.g. sulfonamides, anti-effective;antibacterial agent)
METHODS OF NAMING DRUGS
Chemical name
•The drug’s chemical composition and molecular structure
Generic name (nonproprietary name)
•Name given by the United States Adopted Name Council
Trade name (proprietary name)
•The drug has a registered trademark; use of the name restricted by the drug’s owner (usually the manufacturer)
Chemical name
•(+/-)-2-(p-isobutylphenyl) propionic acid
Generic name
•ibuprofen
Trade name
•Motrin
Pharmaceutics
•The study of how various drug forms influence pharmacokinetic and pharmacodynamic activities.
Pharmacokinetics
•The study of what the body does to the drug:
–Absorption
–Distribution
–Metabolism
–Excretion.
Pharmacodynamics
•The study of what the drug does to the body: –The mechanism of drug actions in living tissues.
Pharmacotherapeutics
•The use of drugs and the clinical indications for drugs to prevent and treat diseases.
Pharmacognosy
•The study of natural (plant and animal) drug sources.
Pharmacogenomics
*The branch of pharmacology which deals with the influence of genetic variation on drug response in patients by correlating gene expression or single-nucleotide polymorphisms with a drug's efficacy or toxicity
Oral Preparations
Liquids, elixirs, syrups Fastest
Suspension solutions •
Powders •
Capsules •
Tablets •
Coated tablets •
Enteric-coated tablets Slowest
PHARMACOKINETICS
Absorption
-The rate at which a drug leaves its site of administration, and the extent to which absorption occurs.
–Bioavailability
–Bioequivalent
Factors That Affect Absorption
•Administration route of the drug
•Food or fluids administered with the drug
•Dosage formulation
•Status of the absorptive surface
•Rate of blood flow to the small intestine
•Acidity of the stomach
•Status of GI motility
Distribution
-The transport of a drug in the body by the bloodstream to its site of action.
•Protein-binding
•Water soluble vs. fat soluble
•Blood-brain barrier
•Areas of rapid distribution: heart, liver, kidneys, brain
•Areas of slow distribution: muscle, skin, fat
Metabolism(also known as Biotransformation)
-The biologic transformation of a drug into an inactive metabolite, a more soluble compound, or a more potent metabolite.
•Liver (main organ)
•Kidneys
•Lungs
•Plasma
•Intestinal mucosa
Factors that decrease metabolism:
•Cardiovascular dysfunction
•Renal insufficiency
•Starvation
•Obstructive jaundice
•Slow acetylator
•Erythromycin or ketoconazole drug therapy
Factors that increase metabolism:
•Fast acetylator
•Barbiturates
•Rifampin therapy
Delayed drug metabolism results in:
•Accumulation of drugs
•Prolonged action of the effects of the drugs
Stimulating drug metabolism causes:
•Diminished pharmacologic effects
Excretion
-The elimination of drugs from the body
•Kidneys (main organ)
•Liver
•Bowel
–Biliary excretion
–Enterohepatic circulation
Half-Life
•The time it takes for one half of the original amount
of a drug in the body to be removed.
•A measure of the rate at which drugs are removed from the body.
Pharmacodynamics:Mechanisms of Action
Drug actions:
•The cellular processes involved in the drug and
cell interaction
Drug effect:
•The physiologic reaction of the body to the drug
Onset
•The time it takes for the drug to elicit a therapeutic response
Peak
•The time it takes for a drug to reach its maximum therapeutic response
Duration
•The time a drug concentration is sufficient to elicit a therapeutic response
The ways by which drugs can produce therapeutic effects:
•Once the drug is at the site of action, it can modify the rate (increase or decrease) at which the cells or tissues function.
•A drug cannot make a cell or tissue perform a function it was not designed to perform.
•Receptor interaction
•Enzyme interaction
•Nonspecific interactions
PHARMACOTHERAPEUTICS:
Types of Therapies:
•Acute therapy
•Maintenance therapy
•Supplemental therapy
•Palliative therapy
•Supportive therapy
•Prophylactic therapy
Monitoring
•The effectiveness of the drug therapy must be evaluated.
•One must be familiar with the drug’s
•intended therapeutic action (beneficial)
•and the drug’s unintended but potential side effects (predictable, adverse drug reactions).
•Therapeutic index
•Drug concentration
•Patient’s condition
•Tolerance and dependence
•Interactions
•Side effects/adverse drug effects
Therapeutic Index
-The ratio between a drug’s therapeutic benefits and its toxic effects
Tolerance
-A decreasing response to repetitive drug doses
Dependence
-A physiologic or psychological need for a drug
Interactions may occur with other drugs or food
•Drug interactions: the alteration of action of a drug by:
– Other prescribed drugs
– Over-the-counter medications
– Herbal therapies
Interactions
•Additive effect
•Synergistic effect
•Antagonistic effect
•Incompatibility
MEDICATION MISADVENTURES
Adverse drug events
•ALL are preventable
•Medication errors that result in patient harm
Adverse drug reactions
•Inherent, not preventable event occurring in the normal therapeutic use of a drug
•Any reaction that is unexpected, undesirable, and occurs at doses normally used
Some adverse drug reactions are classified as side effects.
•Expected, well-known reactions that result in little or no change in patient management
•Predictable frequency
•The effect’s intensity and occurrence is related to the size of the dose
Adverse Drug Reaction
-an undesirable response to drug therapy
•Idiosyncratic
•Hypersensitivity reactions
•Drug interactions
Iatrogenic Responses
Unintentional adverse effects that are treatment-induced
•Dermatologic
•Renal damage
•Blood dyscrasias
•Hepatic toxicity
Other Drug-Related Effects
•Teratogenic
•Mutagenic
•Carcinogenic
Routes
•A drug’s route of administration affects the rate
and extent of absorption of that drug.
–Enteral
–Parenteral
-Topical
Enteral Route
•Drug is absorbed into the systemic circulation through the oral or gastric mucosa, the small intestine, or rectum.
–Oral
–Sublingual
–Buccal
–Rectal
First-Pass Effect
-The metabolism of a drug and its passage from the liver into the circulation.
•A drug given via the oral route may be extensively metabolized by the liver before reaching the systemic circulation (high first-pass effect).
•The same drug—given IV—bypasses the liver, preventing the first-pass effect from taking place, and more drug reaches the circulation.
•Routes that bypass the liver:
–Sublingual Transdermal
–Buccal Vaginal
–Rectal Intramuscular
–Intravenous Subcutaneous
–Intranasal Inhalation
*Rectal route undergoes a higher degree of first-pass effects than the other routes listed.
Parenteral Route
•Intravenous*
•Intramuscular
•Subcutaneous
•Intradermal
•Intrathecal
•Intraarticular
*Fastest delivery into the blood circulation
Topical Route
•Skin (including transdermal patches)
•Eyes
•Ears
•Nose
•Lungs (inhalation)
•Vagina
and extent of absorption of that drug.
–Enteral
–Parenteral
-Topical
Enteral Route
•Drug is absorbed into the systemic circulation through the oral or gastric mucosa, the small intestine, or rectum.
–Oral
–Sublingual
–Buccal
–Rectal
First-Pass Effect
-The metabolism of a drug and its passage from the liver into the circulation.
•A drug given via the oral route may be extensively metabolized by the liver before reaching the systemic circulation (high first-pass effect).
•The same drug—given IV—bypasses the liver, preventing the first-pass effect from taking place, and more drug reaches the circulation.
•Routes that bypass the liver:
–Sublingual Transdermal
–Buccal Vaginal
–Rectal Intramuscular
–Intravenous Subcutaneous
–Intranasal Inhalation
*Rectal route undergoes a higher degree of first-pass effects than the other routes listed.
Parenteral Route
•Intravenous*
•Intramuscular
•Subcutaneous
•Intradermal
•Intrathecal
•Intraarticular
*Fastest delivery into the blood circulation
Topical Route
•Skin (including transdermal patches)
•Eyes
•Ears
•Nose
•Lungs (inhalation)
•Vagina