Pharmacology Chapter on Drug-Receptor Interactions

Drugs that are easily absorbed into cells and tissues, often because they are fat-soluble (lipid-soluble). They can interact with receptors located in the cytoplasm or nucleus.

A protein or glycoprotein that acts as a target for a drug. They are essential for cellular communication and function.

A type of drug target that is an ion channel located within the cell membrane. These channels control the flow of specific ions in and out of cells.

An enzyme that plays a crucial role in the production of prostaglandins, which are involved in pain, inflammation, and fever. NSAIDs like ibuprofen work by inhibiting COX.

These bind to receptors and either activate or inhibit them, causing a change in cellular function.

A drug that binds to and blocks the GABA receptor, a type of ion channel. This can have a calming or sedative effect.

The interaction between a drug and its receptor is based on the principle of complementary fit, meaning the drug's shape and properties must match those of the receptor's binding site.

The degree to which a drug preferentially binds to and interacts with its target receptor, reducing the likelihood of binding to other receptors.

A drug's effect on a cell is only noticeable if the cell expresses the receptor that the drug targets.

The fraction of receptors occupied by a drug depends on its concentration in the biological environment and the strength of its bond to the receptor.

A graph plotting the effect of a drug against its concentration. It shows a direct correlation between drug concentration and the response it generates.

A drug that mimics the effect of a natural messenger molecule (like a hormone or neurotransmitter) by binding to the same receptor and activating it.

The combined effect of two drugs, which act by the same mechanism, is equal to the sum of their individual effects. For example, if medication A lowers blood pressure by 10 points and medication B lowers blood pressure by 5 points, using both together will lower blood pressure by 15 points.

The combined effect of two drugs with the same mechanism, where the combined effect is greater than the sum of individual effects.

The combined effect of two drugs is greater than the sum of their individual effects. It's like one drug amplifies the other.

A drug that enhances the effect of another drug. The synergist may work by increasing the concentration of the other drug at its receptor sites.

The combined effect of two drugs, where one drug has a minimal effect on its own but significantly increases the effect of the other drug.

Competitive antagonism occurs when an antagonist molecule competes with the agonist molecule for the same binding site on a receptor. This competition reduces the likelihood of the agonist binding and decreases its effects.

This type of antagonism is surmountable because the effects of the antagonist can be overcome by increasing the concentration of the agonist. The agonist can outcompete the antagonist by reaching higher concentrations and occupying more of the binding sites.

In this type of antagonism, the antagonist binds irreversibly to the receptor, effectively making the receptor unavailable for agonist binding. This creates a long-lasting antagonistic effect.

The agonist log D-R curve is a graph that shows the relationship between the concentration of the agonist and the response it produces. In the presence of a competitive antagonist, the curve shifts to the right, indicating a need for a higher concentration of agonist to achieve the same level of response.

The presence of an irreversible antagonist reduces the maximum response achievable by the agonist. Even with increased agonist concentration, the response will not reach the same maximum as when there is no antagonist present.

The slope of the agonist log D-R curve represents the efficiency of the agonist in producing a response. The presence of an irreversible antagonist reduces the slope of the curve, indicating that the agonist is less efficient at producing a response despite increased concentration.

The binding affinity of a drug refers to its ability to bind to a receptor. The higher the affinity, the more tightly it binds. In competitive antagonism, the relative affinities of the agonist and antagonist determine how effectively they compete for the binding site.

The concentration of a drug in a system also plays a role in determining the overall effect. A higher concentration of the agonist increases chances of binding and potentially overcoming the antagonism.

A decrease in the effectiveness of a drug over time due to repeated exposure. This happens when the body adapts to the drug's presence, requiring higher doses for the same effect.

A type of acquired tolerance that develops rapidly within hours or days. It often represents a protective mechanism against the drug's effects.

A type of acquired tolerance where the body develops resistance to multiple drugs within the same class. For example, developing tolerance to one benzodiazepine could lead to tolerance to other benzodiazepines.

This occurs when the body exhibits a lesser response to a drug compared to the average expected response. It can be caused by variations in how the drug is processed or how it interacts with the body.

This occurs when the body shows an exaggerated response to a drug compared to the average expected response. The individual might experience a more significant effect with a standard dose.

Variations in how a drug is absorbed, distributed, metabolized, or eliminated (ADME) from the body. These variations can affect the drug's concentration at its target site.

Variations in how drugs interact with the body, affecting the way a drug binds to its target or the signaling pathways involved. These variations can influence the drug's overall effect.

Differences in drug response among individuals. This can happen due to genetics, age, sex, lifestyle, and co-existing medical conditions.

The antagonist drug binds to a different site on the receptor than the agonist, preventing the agonist from activating the receptor. This effect cannot be reversed by increasing the concentration of the agonist.

The antagonist drug directly interacts with the agonist in solution, making the agonist inactive and unable to bind to its receptor. It's like preventing two people from meeting!

A situation where even when all receptors are occupied by an antagonist, the agonist still produces a partial response. This is because extra receptors are available, like a backup plan.

The maximum response of a drug is reduced in the presence of an antagonist. This is often observed in non-competitive antagonism.

When an antagonist binds to a receptor, it might prevent the agonist from causing its full effect, even if the agonist is at a high concentration.

A tumor that produces and releases large amounts of adrenaline (epinephrine). This can lead to high blood pressure and heart rate.

A drug that blocks the action of adrenaline by binding to alpha-adrenergic receptors. It's used to manage phaeochromocytoma.

Picrotoxin is a drug that blocks the flow of chloride ions through GABAa receptors. It acts from the inside of the channel, preventing the receptors from working properly.