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Discussion 2 Rosanna Octaviano

Pharmacokinetics and Pharmacodynamics

Pharmacokinetics is the study of how the body interacts upon a drug. Pharmacokinetic components of drug actions include routes of administration, absorption and distribution, binding, inactivation and excretion.

Pharmacodynamics is the study of the effect of a drug on the body, both the therapeutic effects and side effects of drugs. It deals with the interaction of drug molecules with specific receptors.

Pharmacokinetics and Pharmacodynamics

Pharmacokinetics describes the drug concentration-time course in body fluids resulting from administration of a certain drug dose while Pharmacodynamics the observed effect resulting from a certain drug concentration.

Pharmacokinetics is the movement of drugs through the body, while pharmacodynamics is the body’s biological response to drugs.

Pharmacogenetics and Pharmacogenomics

Pharmacogenetics is the study of the genetic basis for variability in drug response among individuals. It may help determine how an individual’s genes are affected by the medications.

Pharmacogenomics is the study that investigates how variations in genes affect response to medications, using a person’s genetic profile to predict a drug’s efficacy or toxicity.

Pharmacogenetics and Pharmacogenomics

Pharmacogenetics and Pharmacogenomics can both provide insight on gene mutations.

Pharmacogenomics focuses on the simultaneous impact of multiple mutation in the genome that may determine the patient’s response to drug therapy while pharmacogenetics deals with the genetic causes of individual variation in drug response

First pass, Half-life, and Steady State

• First pass metabolism is the process when a drug is metabolized by the liver after the drug is administered orally and is chemically altered by enzymes before passing to the general circulation.

• Half life is the amount of time needed for 50% of the drug to be eliminated. It determines the time required to reach the steady state plasma level.

• Steady state is the desired blood concentration and is reached once the rate of drug input and elimination are equivalent.

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Potency, Efficacy, and Tolerance

• Potency refers to the amount of a drug of how much of the concentration is needed to produce a specific effect.

• Efficacy is the ability of a drug to produce a maximum effect at any dosage

• Tolerance is a condition when there is reduced response that results from repeated drug exposure.

Inducers and Inhibitors

Inducers are substances that enhance or speed up the medication metabolism thereby reduces the levels of medications in the blood

Inhibitors are substances that slow down the medication metabolism thereby increases the drug level of medication in the blood.

Therapeutic Window and Therapeutic Index

Therapeutic window is a range of drug concentrations that provide therapeutic response, so that it can be effective not causing unwanted side effects or toxicity.

Therapeutic index is a ratio that compares blood concentration at which a drug becomes toxic and the concentration at which the drug is effective.

Upregulation and Downregulation

Upregulation is the process by which a cell increases its response to a substance resulting in an increase in number of receptors

Downregulation is characterized by decrease in receptor number of cell due to increased exposure or long term exposure to agonist

P450 Enzymes

• P450 enzymes are responsible for oxidizing most psychoactive drugs including antidepressants, morphine and amphetamines. They catalyze the elimination of most drugs and toxins from the body.

Agonist and Antagonist

• An agonist is a substance that can bind and activate a receptor to induce a biological reaction.

• Antagonist is a substance that binds to the receptor producing no change. They also block agonist activity by preventing agonists from binding to receptors

• The main difference is that agonists simulates the intended reaction whereas the antagonist binds to the receptor and slows/stops responses.

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References

Meyer, J.S., et al (2022) Psychopharmacology Drugs, the Brain, and Behavior (Fourth Edition), New York: Oxford University Press.

Stahl, S.M. (2013). Stahl’s Essential Psychopharmacology. Neuroscientific Basis and Practical Applications (4th edition). Cambridge University Press.

Woo, T.M. & Robinson, M .V. (2019). Pharmacotherapeutics for advance practice Nurse Prescribers ( 5th ed). F.A. Davis Company.

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