basic pharma notes

7/29/2019 Basic Pharma Notes

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Pharmacology- Science that deals with the fate of the drugs in

the body and their actions on the body.

- Closely related to

PharmacyScience of the preparation of drugsTherapeutics

Treatment of disease, by drugs and othermeans

Both a basic (i.e., molecules, cells, organ, etc) and

clinically applied science (i.e., on human

species for treatment of disease)


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Purpose of Pharmacology- To test drugs quantitatively and standardize

them so that they are available to the doctor

and patient in uniform and dependable forms.

- To determine how drugs produce their effects

- To develop new drugs

- To establish rational and safe dosaging


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What is a Drug?Any substance, other than a normal constituent

of the body or one that is required for normal

body function (e.g., food, water, oxygen), thatwhen applied to or introduced into a living

organism, has the effect of altering body

function/s.


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Drug Names and Classifications

Chemical Name

Chemical makeup

Generic name

Name the manufacturer gives a drug

Nonproprietary drug, not protected by

trademark

Lowercase letter


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Brand name

Trade name

Copyrighted and used exclusively


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Guidelines for drug names

Active component in single word

When two or more components, list

principal, active ingredient first

Use of common stems for drug groups


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Generic Drugs

Must be equivalent to the brand-namedrugs

FDA has an A/B rating system to establish

therapeutic equivalence of generic drugs FDA has identified generics not

therapeutically equivalent; in OrangeBook


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Generic Drugs

Patent grants the sponsor the sole right tomanufacture a drug while the patent is in

effect

Under a patent, generic and brand nameof a drug belong to the drug sponsor

Once patent expires, other companies can

produce this drug as a generic


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Components of a DrugActive Ingredients --- the substance or

substances that produce the

pharmacological and therapeutic action.

Inactive or Inert Ingredients --- thesubstance or substances that have no

therapeutic effect but are necessary inthe formulation of the preparation.


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Medicinal Drugs

Pharmacologic effects

Drug actions on living system

Classifications Therapeutic drugs: relieve symptoms

of a disease

Prophylactic drugs: prevent ordecrease the severity of disease


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Synthetically Produced Drugs

Many drugs produced syntheticallyfrom chemical substances

Sulfonamides, aspirin, sodium

bicarbonate

Biopharmaceuticals

Produced by recombinant DNA

technology


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Classifications of DrugsAccording to origin:

Natural Preparation or galenicals

Pure compounds Semi-synthetic substances

Purely synthetic compounds


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Pharmacognosy

Study and identification of natural

sources for drugs

Plants, animals, minerals, chemicals,

Ergotamine from rye fungi, digoxin from

foxglove, and morphine from the opium

poppy


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Classifications of DrugsAccording to its preparation:I. Oral solid forms

II. Oral solutions

III. Oral suspension

IV. Parenterals

V. Topical preparations applied to the skin

VI. Other topical preparations


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Classifications of DrugsAccording to BFAD product registration:

Prescription DrugsorEthical Drugs

Non-Prescription DrugsorOver-the-Counter (OTC) Drugs.

Dangerous Drugs*

ProhibitedRegulated

* These can be bought only with special prescriptions controlled bythe Dangerous Drugs Boardlike the S-2 prescription.


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Classifications of DrugsAccording to therapeutic action (Philippine National Drug Formulary):

Drugs Acting on the Nervous System

Drugs Acting on the Musculoskeletal System and Joints

Anti-Infectives

Immunologicals Cardiovascular Drugs

Diuretics

Respiratory Drugs

Anti-Allergics

Antineoplastics and Immunosuppressants Drugs Affecting the Blood

Blood Products and Blood Substitutes


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Classifications of DrugsAccording to therapeutic action:(Philippine National Drug Formulary): Antidotes

Gastrointestinal Drugs

Hormones and Hormone Antagonists

Drugs Acting on the Uterus Solutions Correcting Water Electrolyte, Acid-Base, and Caloric

Disturbances

Diagnostic Agents

Dermatologicals and Mucous Membrane Agents (Topical)

Opthalmological Preparations Ear, Nose, and Throat Preparations

Vitamins and Minerals

Disinfectants


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Routes of Drug Administration


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Scope and Division of Pharmacology


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Alternative Medicine

Billions of dollars are spent every

year on alternative medicine

Includes herbs, supplements, and

homeopathic remedies


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Concerns About

Alternative Medicine

Legitimate scientific data is scarce

Patients often do not tell prescriber and

pharmacist they are taking alternative

medicines Interaction can often occur between prescribed

drug and alternative medicine

Many alternative medicines are not

covered by governmental regulations


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Clinical Trials of New Drugs

Patients typically separated into 2 groups

Experimental group receives drug to be tested

Control group receives a standard treatment for

the illness or placebo

Double blind study

Trial participants nor study staff know whether a

particular participant is in which group Best way to determine what a new drug does


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Four Phases of Clinical Trials

Phase I Studied in 20 to 100 healthy people

Phase II Studied in patients who have the

condition it is intended to treat

Phase III Compared to commonly used

treatments

Phase IV Continuation of testing after approved

for marketing


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FDA Approval Process

FDA approval process took 7 to 10 years

FDA has made urgently needed drugs

available sooner

Prescription User Fee Act of 1992shortened the FDAs review process for

new drugs

Act on standard applications within 10 months

Act on priority applications within 6 months


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FDA Approval Process

FDA considers a new drug safe enough to

be approved when the benefits outweigh

the risk

Drugs are not tested on pregnant women

Based on all available information, drugs

are grouped into safety categories for use

during pregnancy


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FDA Pregnancy Categories

Category Risk Level

A No risk

B Risk cannot be ruled out

C Caution is advised

D Is a definite risk

X Do not use


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Postmarketing Surveillance

Office of Compliance, a branch of the FDA,

oversees drug manufacturing process

Professionals and consumers can report serious

adverse reactions to MedWatch, FDAs Medical

Products Reporting Program If drug poses a health risk, FDA will remove it

from the market even though it has already been

approved

Ensures that manufacturers follow good

manufacturing practices in FDA regulations


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Removing Drugs from

the Market

Safe does not mean harmless

every drug has risks

FDA evaluates significant adverse effects

to determine the seriousness andlikelihood that they were drug related

If risk outweighs the benefits, FDA will ask

manufacturer to withdraw a drug from the

market voluntarily


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Black Box Warning

For drugs on the market and found to be

problematic, but still provide therapy for

specific conditions

Black Box warning on package insert

Alerts prescribers to known problems

Thousands of drugs on the market have

Black Box warnings


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Controlled Substances

Controlled Substances Act, 1970

Combat escalating drug abuse

1973, establishment of DEA, branch

of the U.S. Justice Department


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Controlled Substances

Label Abuse Potential

C-I highest potential

C-II high possibility, which can lead

to severe dependence

C-III less potential

C-IV low potential

C-V lowest potential


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Drug Actions

Drugs work by a variety of chemical

mechanisms

Body continually fights to maintain a state

ofhomeostasis (stability) Achieved by a system of control and feedback

mechanisms

Drugs can be used to restore and maintain

homeostasis


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Messengers and Receptors

Cells communicate through the action of

chemical messengers, which theyproduce and send into extracellular fluids

Some chemical messengers: histamine,prostaglandin, bradkinin

Messengers recognize and communicate

with target cells via receptors (specific

protein molecules)


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Receptors

Receptor site may have specificity

Affinity is the strength by which aparticular chemical messenger binds

to its receptor site or cell


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Drug Receptor Theory


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Pharmacodynamics

The study of mechanism of action of

drugs is what is called

pharmacodynamics.

It is the study ofwhat the drug does to

the body.


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Mechanisms of Drug Action

Drugs act like chemical messengers toperform their specific actions in the body

By binding to receptors on or within body

cells, drugs can Mimic orblock the action of chemical

messengers

Exert powerful and specific actions inthe body


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Agonist drugs bind to a particularreceptor and trigger the same cellular

response as the bodys own chemical

messenger Antagonist drugs compete to block the

action of the endogenous messenger


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Some drugs produce their effects by

embedding themselves in cellmembranes

Cell membranes made up mostly of

lipids, which repel water

Effectiveness of these drugs is

related to their lipid solubility


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Some drugs combine with specificmolecules in the body such as enzymes,transport proteins, and nucleic acids

Example: some antidepressants Some drugs act without any direct

interaction within the cell

Example: Mannitol interferes osmotically with

water reabsorption by the kidneys


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Pharmacokinetics

Activity of a drug within the body over a

period of time

Includes ADME: absorption, distribution,metabolism, and excretion of a drug

Also includes the metabolites of a drug inrelation to the time they are in the body


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Absorption,

Distribution,

Metabolism,

and Excretion

of a Drug


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AbsorptionProcess of movement of a drug from

the site of application into the

extracellular compartment of thebody

Rate of absorption affects duration andintensity of drug action


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Distribution Rate of distribution is determined by the

physicochemical characteristics of the drug,

cardiac output and blood flow.

Drug Reservoirs

Plasma Protein and other extracellular

reservoirs

Cellular reservoirs

Fat


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ADME

Absorption: process whereby a drugenters the circulatory system

Distribution: process by which adrug moves from the blood into other

body fluids and tissues and to its

sites of action

Blood flow is rate-limiting factor


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ADME

Metabolism: process by which drugs arechemically converted to compounds and

then excreted through metabolic pathways

Metabolite is substance into which a drug isconverted by metabolism

Induction: drugs enhance drug metabolism

Inhibition: drugs decrease drug metabolism


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ADME

Elimination: removal of a drug or itsmetabolites from the body

Clearance is the rate at which a drugis eliminated from a specific volume

of blood per unit of time


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Excretion / Elimination

- More polar, less lipid soluble

compounds are more easily eliminated

- Kidney, GIT, Breast milk, Pulmonary


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DiscussionWhat are the primary sites of

elimination in the body?

The kidneys and the liver, but can also

be exhaled by the lungs or excreted in

perspiration.


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Pharmacokinetic Parameters

Pharmacokinetic processes determine

how a drug should be administered to

obtain a specific response

Treat disease state, not produce toxicity


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Dose

Quantity of drug administered at one

time

Ceiling effect is a point at which no

clinical response occurs with

increased dosage


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Dose Response Curve

D t i i H th B d


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Determining How the Body

Handles a Drug

Testing of fluids over timedemonstrates how the body handles

a drug Trough is lowest level of drug in blood

Peak is highest level of drug in blood


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BioavailabilityProportion of the drug that reaches the

systemic circulation after a particular

route of administration


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Bioavailability

Portion of dose that becomes biologically

active in the body

Oral drugs go into intestinal wall, liver,

blood, and then to systemic site

Metabolism in the liver before a drug

reaches systemic circulation is first-passeffect

Fi P Eff


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First Pass Effect


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Therapeutic Range

Optimum dosage that provides best

chance for successful drug therapy

When the amount of drug givesdesired response, drug is at

therapeutic level


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Therapeutic Range


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Duration of Action

Length of time a drug gives the

desired response or is at therapeutic

level


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Duration of Action


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DiscussionHow is a drugs volume of distribution,

clearance, and half-life used in dosingdrugs?

Volume of distribution is important forcalculating the loading dose, clearance forcalculating the maintenance dose, and

half-life for determining the dosing interval.


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Drug Effects

Beneficial Responses

Therapeutic Effect: action for whichthe drug is prescribed

Local Effect: confined to a specific partof the body

Systemic Effect: generalized, all-

inclusive effect on entire body

Prescribers Considerations


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Prescriber s Considerations

When Selecting a Drug

Indications: the diseases, symptoms,and conditions for which the drug is

known to be of benefit

Contraindications: the diseases,symptoms, and conditions for which the

drug will not be beneficial and may do

harm


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Side Effects

Secondary responses to a drug other

than the primary therapeutic effect for

which the drug was intended

Allergic responses

Drug dependence, addiction,

abuse, and tolerance


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Drug Interactions

One drug can have an effect on the

action of another

Foods and other substances such as

alcohol and nicotine can interact withdrugs

Common way a substance can interact

is by inducing or inhibiting enzymes thatmetabolize the drug


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Common Drug Relationships

Addition The combined effect of twodrugs equals the sum of

the effects of each drug

taken alone.

Antagonism The action of one drugnegates the action of a

second drug.


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Common Drug Relationships

Potentiation An effect that occurs when a drugincreases or prolongs the action

of another drug, and the total

effect is greater than the sum ofthe effects of each drug used

alone.

Synergism Joint action of drugs in which

their combined effect is moreintense or longer in duration than

the sum of their individual effects.

Factors that Modify Drug


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Factors that Modify DrugEffects and Drug Dosage

Medication errors and patientcompliance

Placebo effects

Body weight and volume distribution

Age

F t th t M dif D


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Gender

Route of administration

Time of administration Rate of elimination

Tolerance

Factors that Modify Drug


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Physiologic variables

Pathologic factors

Genetic factors Drug interactions

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