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1: Pharmacology Overview

Four Basic Pharmacology Terms

  • Drug: Any chemical that can affect living processes.

    • All chemicals can be considered drugs, since, when exposure is sufficiently high, all chemicals will have some effect on life.

  • Pharmacology: The study of drugs and their interactions with living systems.

    • It encompasses the study of the physical and chemical properties of drugs as well as their biochemical and physiologic effects.

  • Clinical pharmacology: The study of drugs in humans.

    • It includes the study of drugs in patients as well as in healthy volunteers.

  • Therapeutics: Also known as pharmacotherapeutics, the use of drugs to diagnose, prevent, or treat disease or to prevent pregnancy.

    • The therapeutic objective of drug therapy is to provide maximum benefit with minimal harm


Properties of an Ideal Drug

  • Effectiveness

    • The most important property a drug can have.

    • An effective drug is one that elicits the responses for which it is given.

  • Safety

    • A safe drug is one that cannot produce harmful effects—even if administered in very high doses and for a very long time.

    • A drug is both a remedy and a poison.

  • Selectivity

    • Selective drug: One that elicits only the response for which it is given.

    • There is no such thing as a wholly selective drug because all drugs cause side effects.

  • Reversible Action

    • It is important that effects be reversible.

    • We want drug actions to subside within an appropriate time.

  • Predictability

    • To maximize the chances of eliciting desired responses, we must tailor therapy to the individual.

  • Ease of Administration

    • An ideal drug should be simple to administer: The route should be convenient, and the number of doses per day should be low.

    • It can enhance patient adherence and it can decrease risk.

  • Freedom From Drug Interactions

    • When a patient is taking two or more drugs, those drugs can interact. These interactions may either augment or reduce drug responses.

    • An ideal drug would not interact with other agents.

  • Low Cost

    • Drugs should be affordable.

  • Chemical Stability

    • Some drugs lose effectiveness during storage.

    • An ideal drug would retain its activity indefinitely.

  • Possession of a Simple Generic Name

    • An ideal drug should have a generic name that is easy to recall and pronounce.

No drug is ideal.


Factors that Determine the Intensity of Drug Responses

Administration

  • The drug dosage, route, and timing of administration are important determinants of drug responses.

  • Accordingly, the prescriber will consider these variables with care. Unfortunately, drugs are not always taken or administered as prescribed.

  • The result may be toxicity if the dosage is too high or treatment failure if the dosage is too low.

  • Poor adherence — when patients do not take medicine as prescribed.

    • Patients should be given complete instructions about their medication and how to take it.

Pharmacokinetics

  • Pharmacokinetic processes determine how much of an administered dose gets to its sites of action.

  • Four major processes of pharmacokinetics

    • Drug absorption

    • Drug distribution

    • Drug metabolism

    • Drug excretion

Pharmacodynamics

  • Pharmacodynamics can be thought of as the impact of drugs on the body.

  • In most cases, the initial step leading to a response is the binding of a drug to its receptor. This drug-receptor interaction is followed by a sequence of events that ultimately results in a response.

  • Placebo effects also help determine the responses that a drug elicits

MA

1: Pharmacology Overview

Four Basic Pharmacology Terms

  • Drug: Any chemical that can affect living processes.

    • All chemicals can be considered drugs, since, when exposure is sufficiently high, all chemicals will have some effect on life.

  • Pharmacology: The study of drugs and their interactions with living systems.

    • It encompasses the study of the physical and chemical properties of drugs as well as their biochemical and physiologic effects.

  • Clinical pharmacology: The study of drugs in humans.

    • It includes the study of drugs in patients as well as in healthy volunteers.

  • Therapeutics: Also known as pharmacotherapeutics, the use of drugs to diagnose, prevent, or treat disease or to prevent pregnancy.

    • The therapeutic objective of drug therapy is to provide maximum benefit with minimal harm


Properties of an Ideal Drug

  • Effectiveness

    • The most important property a drug can have.

    • An effective drug is one that elicits the responses for which it is given.

  • Safety

    • A safe drug is one that cannot produce harmful effects—even if administered in very high doses and for a very long time.

    • A drug is both a remedy and a poison.

  • Selectivity

    • Selective drug: One that elicits only the response for which it is given.

    • There is no such thing as a wholly selective drug because all drugs cause side effects.

  • Reversible Action

    • It is important that effects be reversible.

    • We want drug actions to subside within an appropriate time.

  • Predictability

    • To maximize the chances of eliciting desired responses, we must tailor therapy to the individual.

  • Ease of Administration

    • An ideal drug should be simple to administer: The route should be convenient, and the number of doses per day should be low.

    • It can enhance patient adherence and it can decrease risk.

  • Freedom From Drug Interactions

    • When a patient is taking two or more drugs, those drugs can interact. These interactions may either augment or reduce drug responses.

    • An ideal drug would not interact with other agents.

  • Low Cost

    • Drugs should be affordable.

  • Chemical Stability

    • Some drugs lose effectiveness during storage.

    • An ideal drug would retain its activity indefinitely.

  • Possession of a Simple Generic Name

    • An ideal drug should have a generic name that is easy to recall and pronounce.

No drug is ideal.


Factors that Determine the Intensity of Drug Responses

Administration

  • The drug dosage, route, and timing of administration are important determinants of drug responses.

  • Accordingly, the prescriber will consider these variables with care. Unfortunately, drugs are not always taken or administered as prescribed.

  • The result may be toxicity if the dosage is too high or treatment failure if the dosage is too low.

  • Poor adherence — when patients do not take medicine as prescribed.

    • Patients should be given complete instructions about their medication and how to take it.

Pharmacokinetics

  • Pharmacokinetic processes determine how much of an administered dose gets to its sites of action.

  • Four major processes of pharmacokinetics

    • Drug absorption

    • Drug distribution

    • Drug metabolism

    • Drug excretion

Pharmacodynamics

  • Pharmacodynamics can be thought of as the impact of drugs on the body.

  • In most cases, the initial step leading to a response is the binding of a drug to its receptor. This drug-receptor interaction is followed by a sequence of events that ultimately results in a response.

  • Placebo effects also help determine the responses that a drug elicits

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