Chapter 5: Pharmacodynamics

What is the most accurate definition of pharmacodynamics?

What is a frequency distribution curve?

The following is information about a frequency distribution curve (since I couldn't find or make a picture I like). Please fill in the blanks. A [blank_start]frequency distribution curve[blank_end] is a graphical representation of the number of patients responding to a drug action at different doses. On the [blank_start]Y axis[blank_end] is the number of patients responding; on the [blank_start]X axis[blank_end] is the dose of the medication. The [blank_start]peak[blank_end] of the curve indicates the largest number of patients responding to the drug. The dose in the middle of the curve represents the drug's [blank_start]median effective dose[blank_end], which is the dose required to produce a specific therapeutic response in 50% of a group of patients. Nurses should realize that the standard or average dose predicts a therapeutic response for only [blank_start]half[blank_end] of the population. It is not enough to know the average dose; it's important to know when and how to request whether doses should be adjusted.

A drug's median lethal dose is the dose of the drug that will be lethal in 50% of all animals. A drug's median effective dose is the amount of the drug required to produce a specific therapeutic response in 50% of a group of patients. The therapeutic index is the ratio of a drug's median effective dose to the drugs median lethal dose. When the median effective and median lethal doses are close together on a graph (like shown in the picture), what does that say about the drug?

The median lethal dose is often determined in clinical trials.

What does the graded dose response measure?

The following is information about the graded dose-response relationship and the dose-response curve. Fill in the blanks with the correct information. The graded-dose response relationship and the graded-dose response curve observes and measures the patient's [blank_start]response[blank_end] at different [blank_start]doses[blank_end] of the drug. The 3 distinct phases are: Phase 1: The [blank_start]flat[blank_end] portion of the curve. It indicates that few target cells have been affected by the drug. Phase 2: The [blank_start]straight line[blank_end] portion of the curve. This portion often shows a liner relationship between the [blank_start]amount[blank_end] of drug administered and he [blank_start]degree[blank_end] of response obtained from the patient. Phase 3: A [blank_start]plateau[blank_end] is reached in which increase the drug dose produces no additional therapeutic response. This is usually the point in which the drug has reached its [blank_start]maximal response[blank_end], so giving a higher dose will have no effect.

There are 2 fundamental ways to compare medications within therapeutic and pharmacologic classes. [blank_start]Potency[blank_end] is how much of a drug is needed to produce a therapeutic effect. Drugs that are more potent will produce a therapeutic effect at a [blank_start]lower[blank_end] dose. [blank_start]Efficacy[blank_end] is the [blank_start]magnitude[blank_end] of response that can be produced from a particular drug. From a pharmacological perspective, [blank_start]efficacy[blank_end] is the more important value.

The cellular macromolecule that a drug binds to in order to initiate its effects is called its what?

The vast majority of drug receptors are proteins.

All drugs bind to an extracellular receptor

What is a nonspecific cellular response?

This is a fill in the blank problem about drug-receptor interactions. In simplest terms, a specific activity of the cell is either enhanced or inhibited. When a drug binds to its receptor, it produces a response that [blank_start]mimics[blank_end] the effect of the endogenous regulatory mechanism. A drug that produces the same type of response as the endogenous substance is called an [blank_start]agonist[blank_end]. These drugs sometimes produce a greater maximal response than the endogenous chemical. A [blank_start]partial agonist[blank_end] (or an agonist-antagonist drug) describes a medication that produces a weaker, or less efficacious, response than an agonist. A drug that occupies a receptor and prevents the endogenous chemical from acting is called an [blank_start]antagonist[blank_end]. [blank_start]Functional antagonists[blank_end] inhibit the effects of an agonist by changing pharmacokinetic forms.

An unpredictable an unexplained drug reaction is called what?