Drug Reactions, Interactions & Efficacy

1. Explain how drug–receptor interactions produce pharmacologic effects.

Steps:

• A drug binds to a receptor.

• The drug must fit the receptor (drug selectivity).

• Binding causes a conformational change in the receptor.

• The receptor is then activated or blocked.

• This produces the drug's pharmacologic effect.

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Describe dose–response relationships and the concepts of efficacy and potency.

A dose–response relationship describes the relationship between the drug dose (or concentration) and the pharmacologic response it produces.

Explain receptor regulation including desensitization and down-regulation.

Desensitization

•Decrease in receptor responsiveness despite the receptor still being present

•Receptor becomes less able to activate

•Mechanisms:

•Destruction of the receptors by the cell and modification of receptors

Down-regulation

•Decrease in the number of receptors on a cell surface after prolonged stimulation

•Receptors are removed from the cell membrane

Persistent receptor stimulation → Desensitization → Down-regulation → Reduced drug effect (tolerance)

Receptor regulation refers to the way receptors adjust their activity in response to signaling.

Receptors utilize feedback from their own signaling pathways.

Differentiate therapeutic effects, adverse drug events, and adverse drug reactions.

Adverse Drug Event (ADE): Unfavorable and unintended response to a drug, whether or not it is considered related to the medication. Any injury resulting from the use of medication.

• Medication errors

• Adverse drug reactions

• Allergic reactions (hypersensitivity reactions)

Adverse Drug Reaction (ADR):

• Unintended and harmful response to a medication occurring at doses normally used for treatment, diagnosis, or prevention.

• Can range from mild to severe, and may occasionally be life-threatening.

• The lecture specifically states:

  • "NOT A SIDE EFFECT."

• Therapeutic effect = The medication works as intended, producing a beneficial result (such as pain relief or improved mental health).

• Adverse drug event (ADE) = Any injury or unfavorable event related to medication use. It is the broadest category and includes medication errors, adverse drug reactions, and allergic reactions.

• Adverse drug reaction (ADR) = A harmful reaction to a medication given at its normal dose. ADRs can range from mild symptoms (such as nausea or rash) to severe reactions (such as liver failure or anaphylaxis). The lecture specifically notes that an ADR is not a side effect.

Describe the four types of hypersensitivity reactions to medications.

Hypersensitivity reactions are immune-mediated adverse drug reactions. The lecture classifies them into four types (Type I–IV):

1. Identify common mechanisms of drug–drug and drug–food interactions.

•Drug-Drug interactions

•2 or more medications affect each other inside the body (one can make the other stronger or weaker, blocks or speeds up the break down)

•Examples: Ibuprofen can reduce the affect on BP meds, ASA and blood thinner increases the risk of bleeding, antifungal meds block liver enzymes causing other drugs to stay in your system longer, antibiotics makes liver break down BCP which  decreases the effectiveness of the BCP

•Drug-Food interactions

•What you eat or drink changes how a drug works in your body, can help, hurt or cancel out the medications

•Blocks or increases drug absorption-dairy can block body from absorbing some antibiotics

•Foods act against the drug’s purpose- leafy greens (high in vitamin K) reduce the effect of warfarin (blood thinner)

1. Describe factors that influence medication use in special populations including pregnancy, pediatrics, and geriatrics.

Different patient populations process medications differently because their bodies handle drugs differently.

• Pregnancy increases blood volume, body fat, liver enzyme activity, and kidney filtration, which can change drug absorption, distribution, metabolism, and elimination.

• Pediatrics have developing stomach, liver, and kidney function, so drug absorption, distribution, and metabolism differ from adults.

• Geriatrics experience age-related changes such as slower gastric emptying, increased body fat, decreased body water, lower albumin, and reduced liver metabolism, all of which can affect medication dosing and response.