Pharmacology for Anaesthesia and Intensive Care Flashcards

Comprehensive vocabulary flashcards covering the basic principles of pharmacology, kinetics, and key clinical concepts for anaesthesia and intensive care.

Phospholipid bilayer

A common feature of all cell membranes, about $10\,nm$ thick, arranged with hydrophilic heads on the outside and lipophilic chains facing inwards.

Graham’s law

A principle stating that the rate of passive diffusion of a molecule is inversely proportional to the square root of its molecular size.

Fick’s law

A law stating that the rate of drug transfer across a membrane is proportional to the concentration gradient across that membrane.

pKa

The $pH$ at which $50\%$ of drug molecules are ionised, where the concentrations of ionised and unionised portions are equal.

Bioavailability

The fraction of a drug dose reaching the systemic circulation compared with the same dose given intravenously.

Extraction ratio (ER)

The fraction of drug removed from blood by the liver, which depends on hepatic blood flow, hepatocyte uptake, and metabolic capacity.

Hofmann degradation

A spontaneous metabolic process by which cisatracurium breaks down in a $pH$- and temperature-dependent manner in the plasma.

Prodrug

A drug that has no inherent activity before metabolism but is converted by the body to an active moiety, such as enalapril or diamorphine.

Enterohepatic circulation

A process where drugs excreted in the bile are hydrolysed by bacteria in the small bowel, reabsorbed into the portal circulation, and returned to the liver.

Affinity

A property of a drug describing how well or avidly it binds to its specific receptor.

Intrinsic activity (IA)

A measure of the magnitude of effect a drug has once bound to a receptor, also known as efficacy, valued between $0$ and $1$.

Tachyphylaxis

A rapid decrease in pharmacological response to repeated doses of a drug over a short time period, often due to transmitter store depletion.

Isomerism

The phenomenon where molecules with the same atomic formulae possess different structural arrangements.

Chiral centre

A carbon atom or quaternary nitrogen surrounded by four different chemical groups, allowing for two mirror-image configurations.

Volume of distribution ($V_d$)

The apparent volume into which a drug disperses in order to produce the observed plasma concentration.

Clearance ($Cl$)

The volume of plasma from which a drug is completely removed per unit of time, usually expressed in $ml\,min^{-1}$.

Context-sensitive half-time (CSHT)

The time taken for the plasma concentration to fall by half when an infusion designed to maintain a constant plasma concentration is stopped.

Minimum Alveolar Concentration (MAC)

The steady-state concentration of an inhaled anaesthetic at one atmosphere that prevents reaction to a standard surgical stimulus in $50\%$ of subjects.

Concentration effect

An observed phenomenon describing the disproportionate rate of rise of the alveolar fraction compared with the inspired fraction when high concentrations of $N_2O$ are inspired.

Ryanodine receptor (RYR1)

The specific $Ca^{2+}$ channel on the sarcoplasmic reticulum membrane that, when abnormal, is responsible for Malignant Hyperthermia.

Dibucaine number

The percentage of inhibition of plasma cholinesterase by the local anaesthetic dibucaine, used to identify genetic variants of the enzyme.

Red man syndrome

A histamine-mediated flushing of the face and neck caused by an overly rapid infusion rate of the glycopeptide vancomycin.

Refeeding syndrome

Potentially fatal clinical complications including hypophosphataemia and hypokalaemia resulting from fluid and electrolyte shifts during nutritional rehabilitation of malnourished patients.