Intro to Pharmacology

How a drug gets into the body and how it is distributed throughout.

How a drug effects the body processes. Important in pharmacodynamics is the difference between therapeutic effects and side effects.

Name that describes the chemical make-up of a drug. No one uses this name.

Generic name is the name that is assigned to a drug when it is first given to humans.

The name given to a drug by a company who manufactures it for market.

What part of the nursing process do they occur? Right patient, right dose, right drug, right route, right time.

By chemical structure, by mechanism of action and according to use.

Mechanism of action, because you can tell a lot of things about a drug by its mechanism of action. Use is okay, but one drug can be used for many things, like diphenhydramine. Sleep aid and antihistamine. Chemical structure doesn’t tell what a drug does and therefore is not very useful.

Able to produced the desired result.

A symptom that suggests medical treatment is necessary.

It has to prove that the drug is efficacious for the indication for which it is marketed. It has to proved that the drug is safe.

Using a drug for something other than the approved indication.

Long-term vs. short-term use, over the counter use and prescribed use.

Clinical trials.

The company must test the drug on animals to determine if there are any side effects. Long-term medications are tested for cancer over long periods of time. IND, Investigation New Drug application.

Data from animal testing and a plan for how the drug will be tested on humans.

3, Phase I, Phase II and Phase III

Phase I determines the maximum tolerated dose to be used in future phases. The dose is increased step-wise with healthy people until the adverse effects are not tolerable. This phase includes very few people, less than 50 and sometimes only 10.

The purpose of Phase II is to determine the dosing range for people who have the indication the drug is supposed to help. Blood and urine samples determine distribution and elimination of the drug. People should get better with use. Fewer than 50 people with the indication participate in Phase II.

Phase III is supposed to demonstrate safety and efficacy of the drug in question. Several hundred people with the indication are tested using a double-blinded study. Some receive a placebo (unless it is not ethical and standard treatment is used) and some received the drug being tested. Pregnant women and people with serious comorbidities are excluded. May last months or years. Must do separate Phase III studies for separate indications. Patients are closely monitored and FDA can request a repeat of Phase III or halt process altogether. FDA and company negotiate prescribing dose and information about adverse effects.

Controlled substances are substances that have the potential to be abused and the Drug Enforcement Agency (DEA) regulates them.

Heroine, LSD, high abuse potential

Amphetamines and some opoiods, high abuse potential

Many opioids, some stimulants and anabolic steroids. Moderate

Tranquilizers (like Valium) and weak opioids, low abuse potential

Antidiarrheals and drugs that contain small amounts of opioids in mixtures. Limited abuse potential.

Study of drugs and their interaction with living systems.

Any chemical that can affect a living process.

Almost any molecule in the body: neurotransmitters, enzymes, transport proteins, channels, etc…

• G protein receptor
• Membrane bound receptor
• Ligand gated ion channels
• Transcription factors with activating ligands

The number of receptors it can bind. Fewer receptors increases specificity.

Efficacy. Because if the drug doesn’t work to relieve the symptom then potency doesn’t matter. If a drug is more potent, but has the same efficacy then potency still doesn’t matter.

Receptors for a drug are occupied a higher rates as dose levels increase until all receptors are bound and a plateau is reached.

Takes into account that a drug binding to a receptor may mimic the effect of an endogenous ligans, produce a lesser effect than the endogenous ligand, produce no effect.

It prevents the endogenous ligand from binding to the receptor

The ability of a drug to activate a particular receptor when bound to it.

Endogenous ligands and full agonists.

A competitive antagonist binds reversibly with a receptor in equilibrium with the endogenous ligands. Can be overcome with higher concentration of agonists or endogenous ligands. Non-competitive ligands bind irreversibly with receptors and cannot be overcome by agonists, competitive antagonists or endogenous ligsnds.

Competitive antagonists bind electrostatically and non-competitive antagonists bind covalently.

They downregulate their response. This can be rapid (desensitization) or slow and permanent (tolerance). This lessens the effect of the drug.

Anything that speeds up the drug’s elimination from the body.

Upregulation of receptors and can lead to supersensitivity.

The increased numbers of receptors bind more endogenous ligands causing exaggerated effects.

The dose at which 50% of the people taking the drug are getting a desired effect.

The dose at which the drug is lethal for 50% of the population.

• LD50% / ED50%
• Is a drug with a large therapeutic effect more or less safe?
• Large therapeutic effect is a safer drug. If a drug has a narrow therapeutic effect then lethal dose is more likely.

Undesireable or dangerous effect of a drug brought on by high levels of the drug.

Undesireable effects of the drug a therapeutic levels as a result of the drug’s interaction with the receptor.

A reaction to the drug brought about by the immune system.

They are given another class of drug that produces the same therapeutic effect

NSAIDs, because the reaction is not mediated by antibodies. Someone allergic to NSAIDs can never take NSAIDs again.