Introduction to Pharmacology

Pharmacology is the study of the effect, action, and fate of drugs in the body

A drug is any agent used in the clinical context for diagnosis, cure, mitigation, treatment, or prevention of disease

In lay terminology, a drug is any agent that produces a desired effect on the body

Cocaine and caffeine are considered drugs because of their effects on the body

A drug induces a change in function/action by interacting with the body through a specific mechanism of action

Most drugs produce their effect by binding to a specific receptor, which is a type of molecule in the body

Whether a drug acts as an agonist or antagonist depends on the nature of its interaction with the receptor

Drugs are classified based on origin as either endogenous (produced within the body) or exogenous (introduced from outside the body)

A poison is a substance that produces exclusively harmful effects when administered to the body

"The dose makes the poison" principle attributed to Paracelsus, the father of toxicology

Digoxin becomes toxic when administered above 2 mg/kg, despite its therapeutic use in heart failure

Botox, although used therapeutically for migraines and wrinkles, can cause severe toxicity at high concentrations

The chemical name of a drug describes its molecular structure, such as N-acetyl-para-aminophenol

The generic name of a drug is a standardized name, such as acetaminophen, used regardless of manufacturer

The trade name of a drug, such as Tylenol, is the brand name given by a specific manufacturer

Acetaminophen is the generic name for the drug with the chemical structure N-acetyl-para-aminophenol

The physical and chemical properties of a drug influence its ability to interact with receptors, which directly affects its pharmacological activity

The physical and chemical properties of a drug affect its transport to the target site, impacting how much of the active compound reaches its site of action

The physical and chemical properties of a drug determine how it undergoes inactivation and elimination from the body

The physical state of a drug (solid, liquid, or gas) influences its route of administration

A drug's solubility and transport properties influence its absorption and ability to reach the target site

Natural vs. synthetic drugs and their enantiomeric forms can produce different pharmacological effects

The size, selectivity, and movement of a drug molecule can affect its activity and site of administration

Drug-receptor bonds vary in strength: covalent > electrostatic > hydrophobic, hydrogen, van der Waals

Weak drug-receptor bonds require greater selectivity and specific molecular fit because they need a more specific fit

Drug molecules interact with receptors via a lock-and-key model, emphasizing the importance of molecular shape

Chirality refers to the presence of enantiomers, which can differ in activity, selectivity, metabolism, and duration of action

The action of a drug refers to its molecular mechanism, which may or may not be known

Drug action is not observable, whereas drug effect is observable

The effect of a drug includes both its therapeutic outcomes and undesired side effects

Drug effects are usually known, while drug actions may or may not be understood

Pharmacokinetics describes the processes that determine the time course and movement of a drug throughout the body

The four major components of pharmacokinetics are absorption, distribution, metabolism, and excretion

After administration, a drug must enter the systemic circulation through absorption before it can reach tissues

The distribution phase describes how a drug moves from the blood into tissues, including the site of action

Drug elimination involves the processes of metabolism and excretion, which reduce drug levels in the body

Pharmacodynamics begins once the drug reaches its site of action and interacts with biological targets

A drugs clinical response and overall effectiveness result from both pharmacokinetic and pharmacodynamic factors

Pharmacokinetics describes what the body does to the drug

Pharmacodynamics explains what the drug does to your body

In pharmacokinetics, the site of drug administration is often far from the site of drug action

Orally ingested alcohol must travel from the gastrointestinal tract to the brain to exert its effects

ACE inhibitors are taken via the gastrointestinal tract but act primarily in the lungs, illustrating distribution from the administration site to the action site

Pharmacokinetics studies how the body interacts with the drug, including absorption, metabolism, and drug concentration over time

One core focus of pharmacokinetics is understanding how the body converts an active drug into metabolites for eventual elimination

The minimum effective concentration (MEC) is the lowest plasma concentration at which a drug produces a desired therapeutic effect

The minimum toxic concentration (MTC) is the plasma concentration above which the drug produces undesired or toxic effects

The therapeutic range is the concentration range between the MEC and MTC

The duration of action is the time span during which the drug concentration remains above the MEC

The Tmax is the time after administration when the maximum plasma concentration (Cmax) is reached