Ch. 3 & Ch. 4 Pharmacokinetics and Pharmacodynamics/ Pharmacogenetics

Pharmacokinetics

drug movement through body what body does to drug

Pharmacodynamics

what drug does to the body

drug name categories

1.) chemical

2.) generic

3.) trade

chemical name

based upon the compounds that make up a drug. Because this name uses chemical nomenclature, it can look and sound complicated, making it inappropriate for everyday use

generic name

elected by the United States Adopted Names Council. The generic name is unique for each drug and is based upon the pharmacologic and/or chemical classification of the drug. Often the generic names for drugs within the same pharmacologic class have the same last syllables.

trade (brand) name

chosen by the manufacturer of the drug. The trade name is selected for marketing and is therefore simpler and easier to remember and pronounce than the generic name. Because the trade name is owned by the manufacturer, it is also known as the proprietary name. Trade names always begin with an upper-case letter. The same drug made by different manufacturers will have different trade names but only one generic name.

bioequivalent

the generic drug has the same pharmacokinetic and pharmacodynamic properties as the brand name drug; they share the same therapeutic effects and adverse drug event profile.

equivalent

a less than 20% variance in pharmacokinetics from the brand name drug

drug standards

Dosage

Drug forms

Drug substances and excipients

Biologics

Compounded preparations

Dietary supplements

United States Pharmacopeia and the National Formulary (USP-NF)

sets drug standards for the United States

The Federal Food, Drug, and Cosmetic Act of 1938

empowered the FDA to ensure a drug was safe before marketing. It is the FDA's responsibility to ensure that all drugs are tested for harmful effects; it also required that drugs be labeled with accurate information and have detailed literature in the drug packaging that explains adverse effects.

The Food and Drug Act of 1906

set the standards for drug quality and purity in addition to strength and gave birth to the FDA

Kefauver-Harris Drug Amendment to the 1938 Act (1962)

tightened controls on drug safety, especially experimental drugs and required that adverse reactions and contraindications be labeled and included in the literature

The Controlled Substances Act of 1970

designed to remedy the escalating problem of drug abuse, included several provisions :

- Promotion of drug education and research into the prevention and treatment of drug dependence

- Strengthening of enforcement authority

Establishment of treatment and rehabilitation facilities

- Designation of schedules, or categories, for controlled substances according to abuse liability

Dietary Supplement Health and Education Act of 1994

established labeling requirements for dietary supplements and authorized the FDA to promote safe manufacturing practices. It classified dietary supplements as food

Schedule of Categories of Controlled Substances

-The abuse potential is greatest with schedule I drugs and lowest with schedule V drugs.

-Schedule I drugs are not approved for medical use; they include street drugs and have a high potential for physical and psychological dependence.

-Schedule II through V drugs have accepted medical use.

-Drugs may be listed in more than one schedule category when combined with another drug.

Which schedule of controlled substances has the greatest abuse potential?

Schedule I drugs

Which schedule of controlled substances has the lowest abuse potential?

Schedule V drugs

Are Schedule I drugs approved for medical use?

No, they are not approved for medical use.

What types of drugs are included in Schedule I?

Street drugs with a high potential for physical and psychological dependence.

Do Schedule II through V drugs have accepted medical use?

Yes, they have accepted medical use.

Can drugs be listed in more than one schedule category?

Yes, when combined with another drug.

What are Schedule I substances defined as?

Drugs, substances, or chemicals with no currently accepted medical use and a high potential for abuse.

Give examples of Schedule I substances.

Heroin, LSD, marijuana, MDMA, methaqualone, and peyote.

What are Schedule II substances defined as?

Drugs, substances, or chemicals with a high potential for abuse, with use potentially leading to severe psychological or physical dependence.

Give examples of Schedule II substances.

Combination products with less than 15 mg of hydrocodone per dosage unit, cocaine, methamphetamine, methadone, hydromorphone, meperidine, oxycodone, fentanyl, dextroamphetamine, dextroamphetamine/amphetamine, and methylphenidate.

What are Schedule III substances defined as?

Drugs, substances, or chemicals with a moderate to low potential for physical and psychological dependence.

Give examples of Schedule III substances.

Products containing less than 90 mg of codeine per dosage unit, ketamine, anabolic steroids, and testosterone.

What are Schedule IV substances defined as?

Drugs, substances, or chemicals with a low potential for abuse and low risk for dependence.

Give examples of Schedule IV substances.

Alprazolam, carisoprodol, diazepam, lorazepam, zolpidem, and tramadol.

What are Schedule V substances defined as?

Drugs, substances, or chemicals with lower potential for abuse than schedule IV and consist of preparations containing limited quantities of certain narcotics.

Give examples of Schedule V substances.

Cough preparations with less than 200 mg of codeine per 100 mL, codeine/guaifenesin, diphenoxylate/atropine, difenoxin/atropine, and pregabalin.

What did the FDA replace in 2015 regarding pregnancy categories?

The FDA replaced the lettered pregnancy categories A, B, C, D, and X on prescription drug labeling.

What are the new subsections introduced by the FDA for pregnancy labeling?

The new subsections are Pregnancy (includes Labor and Delivery), Lactation (includes Nursing Mothers), and Females and Males of Reproductive Potential.

When will prescription drugs and biologic products submitted after June 30, 2015, use the new labeling format?

They will use the new format immediately.

How will labeling for prescription drugs approved on or after June 30, 2001, transition to the new format?

Labeling will be phased in gradually.

Will pregnancy labeling for OTC drugs change after the 2015 FDA update?

No, pregnancy labeling for OTC drugs will not change.

What is Section 8.1 of the new FDA pregnancy labeling?

Section 8.1 covers Pregnancy and includes Labor and Delivery.

What does Section 8.2 of the new FDA pregnancy labeling cover?

Section 8.2 covers Lactation and includes Nursing Mothers.

What new section was added for Females and Males of Reproductive Potential?

The new section includes Pregnancy testing, Contraception, and Infertility.

What is a requirement for drug labels as new information becomes available?

There is a requirement to update the label as new information becomes available.

Black Box Warning

A notice that a drug may produce serious or even life-threatening effects in some people in addition to its beneficial effects.

This is the strongest safety warning a drug can carry and remain on the market.

Drug absorption

drug movement, disintegration, dissolution

Factors affecting absorption

acidity, motility, food in stomach, stress, temperature, hormonal changes

Constipation

slows down motility

Foods cause absorption

by awakening

Stress effects the gut

slows down, less blood profusion

Onset

Time it takes for drug to reach the minimum effective concentration

Peak

highest concentration in blood

Duration

Length of time drug exerts a therapeutic effect

Therapeutic Drug Monitoring

monitoring drug levels to ensure efficacy and safety (peak & troughs)

Peak drug level

highest plasma concentration of drug at a specific time

Trough drug level

lowest plasma concentration of drug

Agonist

activate receptors, producing a desired response

Antagonists

prevent receptor activation, block response

Side effects

secondary drug effects

Adverse reactions

mild to severe, unintentional, unexpected, undesirable effects

Drug toxicity

drug level exceeds therapeutic range

Tolerance

decreased responsiveness to drug over course of therapy, requires high dose to achieve same therapeutic response

Tachyphlaxis

acute, rapid decrease in response to a drug

Placebo Effect

drug response not attributed to drugs chemical properties

Additive drug effects

sum of effects of two drugs

Synergistic drug effects and potentiation

effects of two drugs in much greater than effects of either drug alone

Antagonistic drug effects

one drug reduces or blocks effect of the other drug

Drug-nutrient interactions

Food may increase, decrease, or delay drug response.

Drug-laboratory interactions

Drugs may cause misinterpretation of test results.

Drug-induced photosensitivity

Drug induced skin reaction caused by sunlight exposure

Pharmacogenetics

Study of how a patient's genomes affect drug response

- Helps individualizeoptimal drug treatment regimens

- Helps decrease drug reactions

- Promotes drug regimen adherence

- Reduces overall healthcare costs

Patients who benefit most from pharmacogenetics

Those taking multiple prescription drugs

Those not responding to the current therapy

Those having adverse drug reactions

Those taking black box warning drugs

Notes about Pharmacogenetic Testing

Pharmacogenetic testing is not available for all drugs

One single test doesn't determine how a patient will respond to all drugs

International Difference

- language barrier may prevent obtaining the same drug

- trade names for the same drug can differ between countries

- drugs with the same trade name may have different active ingredients in different countries