Drug Permeation and Disposition Processes

The movement of a drug from its administration site to the bloodstream.

The distribution of a drug throughout the body, reaching different tissues and organs.

The process of breaking down a drug into smaller, inactive or less active metabolites by the body.

The elimination of a drug and its metabolites from the body.

The fraction of the drug that reaches the systemic circulation unchanged after administration.

The metabolism of a drug before it reaches the systemic circulation.

The reversible binding of drugs to plasma proteins, affecting their distribution and availability for action.

The enzymatic modification of drugs into metabolites involving two phases: oxidation, reduction, or hydrolysis (Phase I) and conjugation reactions (Phase II).

In zero-order kinetics, the time it takes for the drug concentration to reduce by half increases as the drug concentration increases. This means high drug levels can lead to drug accumulation and potential toxicity.

Two formulations of the same drug are considered bioequivalent if they produce similar concentrations of the drug in the body over time. This means they are absorbed at a similar rate and to a similar extent.

Bioequivalence studies are performed to ensure that generic drugs are equivalent to the original brand-name drug, allowing for safe and effective substitution.

Proteins that bind to specific molecules, called ligands, to trigger cellular responses.

Naturally occurring substances in the body that bind to receptors to produce biological responses (e.g., hormones, neurotransmitters).

Drugs that bind to receptors and activate them, causing a biological response.

Drugs that bind to receptors but don't activate them. They block other molecules from activating the receptor, preventing their effects.

Drugs that bind to receptors and produce a weaker response compared to full agonists.

Cell surface receptors that activate intracellular signaling pathways through interactions with G proteins.

Membrane proteins that open in response to ligand binding, allowing ions to pass through and generating an electrical signal.

Cell surface receptors with built-in enzymatic activity.

Intracellular receptors that bind to DNA and regulate gene expression in response to ligand binding.

A dose-response curve illustrates the relationship between the dose of a drug and the magnitude of its effect.

The minimum dose required to elicit a detectable response.

The steepness of the curve, indicating the sensitivity to changes in dose.

The peak response achieved at high doses.

The strength of the attraction between a drug and its receptor.

Receptors present in excess of what's needed for maximum response. A full response can still be achieved even if some receptors are occupied.

The dose of drug that produces a therapeutic effect in 50% of the population.

The dose of drug that causes death in 50% of the population.

The dose of drug that produces a toxic effect in 50% of the population.

An antagonist that binds to the same site as the agonist, competing for binding. Increasing the agonist's concentration can overcome this type of antagonism.

An antagonist that binds to a different site on the receptor or alters its function, preventing the agonist from producing a response.

An agonist produces a dose-dependent increase in response, reaching a maximum effect (Emax) at high doses.

Drugs like Pindolol that partially activate beta adrenergic receptors, producing a weaker effect compared to full agonists. They block the receptors to a lesser degree than full antagonists.

A drug like Labetalol that blocks both beta and alpha 1 adrenergic receptors, leading to decreased heart rate, reduced peripheral resistance, and vasodilation.

Drugs that block the binding of endogenous catecholamines to adrenergic receptors. They competitively bind to receptors, preventing the activation of the receptor.

Drugs that block alpha adrenergic receptors, causing vasodilation, decreased peripheral resistance, and smooth muscle relaxation.

Drugs that block beta adrenergic receptors, leading to decreased heart rate, reduced myocardial contractility, and, in the case of nonselective blockers, bronchoconstriction.

Used to treat hypertension, angina, arrhythmias, migraines, anxiety disorders, and certain benign prostatic hyperplasia symptoms.

Common side effects may include orthostatic hypotension, dizziness, fatigue, bradycardia, cold extremities, and gastrointestinal disturbances.

Serious side effects can include heart block, exacerbation of bronchospasm, exacerbation of heart failure, and masking of hypoglycaemic symptoms in diabetic patients.

Prostaglandins are hormone-like substances that play a role in various bodily functions, including inflammation, pain, fever, blood clotting, and smooth muscle contraction and relaxation.

Histamine is a chemical messenger that is released from mast cells and other cells in response to injury or allergic reactions. It plays a crucial role in inflammation, immune responses, and gastric acid secretion.

Serotonin is a neurotransmitter that influences various physiological functions, including mood regulation, sleep-wake cycles, appetite, and gastrointestinal motility. It's often referred to as the "happiness hormone."

Leukotrienes are potent inflammatory mediators, particularly involved in asthma. They contribute to airway narrowing, increased mucus production, and airway inflammation.

Prostaglandin analogues are medications that mimic the actions of naturally occurring prostaglandins. They are used to prevent gastric ulcers, induce labor, and facilitate medical abortions.

Antihistamines are medications that block histamine receptors, preventing histamine from binding and triggering allergic reactions. They are used to relieve allergy symptoms like itching, sneezing, and runny nose.

Serotonin agonists are drugs that stimulate serotonin receptors, often used for treating migraines and cluster headaches. They enhance the effects of serotonin.

Serotonin antagonists are drugs that block serotonin receptors, used to prevent nausea and vomiting, especially associated with chemotherapy or surgery. They block the actions of serotonin.