Pharmacodynamics

Definitions: Effects of drugs on the body. Describes relationship between drug concentration and effect.

Receptor: component of the biological system to which a drug binds to bring about a change in function of the system

Agonist: A drug that activates its receptor upon binding.

Effector: Component of the biological system that accomplishes the biologic effect after being activated by the receptor; often a channel or enzyme

Pharmacologic antagonist: A drug that binds to its receptor without activating it.

Competitive antagonist: A pharmacologic antagonist that can be overcome by increasing the dose of agonist.

Irreversible antagonist: A pharmacologic antagonist that cannot be overcome by increasing the dose of agonist.

Physiologic antagonist: A drug that counters the effects of another by binding to a different receptor and causing opposing effects.

Chemical antagonist: A drug that counters the effects of another by binding the drug and preventing its action

Partial agonist: A drug that binds to its receptor but produces a smaller effect at full dosage than a full agonist.

Kd: The conc of drug that results in binding to 50% of the receptors.

Efficacy: The maximum effect a drug can bring about, regardless of dose

Potency: The dose conc. required to bring about 50% of a drug's maximal effect

ACh receptors:

Nicotinic ACh rcp are ligand-gated Na⁺/K⁺ channels; N_N (found in autonomic ganglia) and N_M (found in neuromuscular junction) subtypes.

Muscarinic ACh rcp are G-protein-coupled rcp that act through 2nd messengers; 5 subtypes: M1, M2, M3, M4, M5