1. Active drug or metabolite can be excreted in the feces 2. Drugs can be secreted and subsequently reabsorbed 3. Metabolites can be secreted and then reconverted to the active drug in the intestinal lumen by bacterial enzymes and reabsorbed (e.g. oral contraceptives)

Exam 1 Terms Flashcards by Ryan Schwanke

Topical Route of Drug Administration

Dermal, Intranasal, Mucous Membrane, Eyes

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Enteral Route of Drug Administration

Buccal, Sublingual, Oral, Rectal

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Parenteral Route of Drug Administration

Intravenous, Intramuscular, Subcutaneous, Transdermal, etc.

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Membrane proteins that control the influx of essential nutrients and ions and the efflux of cellular waste, environmental toxins, and drugs.

Transporters

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Include Organic Anion Transporting Polypeptides (OATPs), Organic Anion (OATs), and Organic Cation (OCTs) transporters.

SLC (Solute Carrier)

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Active transporters that rely on ATP Hydrolysis to actively pump their substrates across membranes.

ABC (ATP Binding Cassette)

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Pharmaceutical factors involved in GI absorption via passive diffusion.

Solubility/Concentration, Stability, and Controlled Release Preparations

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Chemical properties of drugs involved in GI absorption via passive diffusion.

Molecular Size, Lipid Solubility, and Ionization Coefficient (pKa)

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Drugs that cross membranes by passive diffusion tend to accumulate in compartments where the degree of ionization is the greatest.

Ion Trapping

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Relates the amount of drug in the body to the concentration of drug in the vascular compartment.

Volume of Distribution (Vd)

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Normal Vd in the vascular compartment.

3-5 L

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Normal Vd in the extracellular compartment.

10-20 L

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Normal Vd in the total body water compartment.

35-50 L

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Important plasma proteins for drug binding.

Albumin (acidic drugs), Alpha1 Acid Glycoprotein (basic drugs), Lipoproteins, Specific hormone carrier proteins

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Consequences of drug binding to plasma proteins.

Reduces the concentration of unbound drug, may slow the distribution and elimination of the drug (depot), and represents a potential site of drug interaction.

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There is an increased risk of an adverse drug reaction (ADR) with:

Increased protein binding, decreased Vd, and decreased elimination kinetics.

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Reaction that results in relatively minor chemical modification of the parent compound.

Phase I Reaction; metabolite more polar

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These reactions are conjugations.

Phase II Reaction; metabolites are pharmacologically inactive

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Enzyme located in liver and several other organs that oxidatively metabolizes most drugs.

Cytochrome-P450; localized in the sER; dependent on NADPH and molecular O2; low degree of specificity

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Quantitatively most important phase II reaction.

Glucuronidation

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Type of drugs that can be secreted by the liver into the bile (Biliary-fecal route).

Amphipathic, lipid-soluble conjugated metabolites, with a MW > 300

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Enterohepatic Cycle

Active drug or metabolite can be excreted in the feces
Drugs can be secreted and subsequently reabsorbed
Metabolites can be secreted and then reconverted to the active drug in the intestinal lumen by bacterial enzymes and reabsorbed (e.g. oral contraceptives)

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Renal Clearance

Cl = (U x V) / P

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Intrinsic ability of the liver to eliminate a drug in the absence of limitations imposed by blood flow.

Intrinsic Clearance

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Orally administered drugs must pass through the liver before gaining access to the systemic circulation.

First Pass Effect

Cl = 0

Drug filtered and completely reabsorbed

Cl = ~120 ml/min

Drug filtered and not reabsorbed

Cl = ~650 ml/min

Drug filtered and maximally secreted

The study of the time course of drug concentration in the body, usually as reflected in the plasma concentration.

Pharmacokinetics

Characterized by a constant fractional change per unit time.

First order kinetics (exponential kinetics); rate constant (ke)

Characterized by a constant amount of change per unit time.

Zero order kinetics (saturation kinetics)

The time required for 50% of the drug remaining in the body to be eliminated.

Half-life (t1/2); for first order kinetics

The volume of biological fluid such as blood or plasma that would have to be completely freed of drug to account for the rate of elimination.

Clearance; expressed in volume per unit

One Compartment Model

1. Body is a single compartment 2. Distribution of drugs is uniform and rapid 3. Elimination of drugs conforms to first order kinetics

Two Compartment Model

1. Body contains two compartments 2. All kinetics are first order 3. Elimination is from the central compartment

When a drug is administered intravenously, the plasma concentration will increase until the rate of elimination and administration are equal.

Plateau Principle

Steady-State Concentration

Css = dosing rate / Cl

Number of half-lives required to reach steady state.

4-6

The amount of drug required to achieve a given steady-state value in plasma is the amount that must be in the body when the desired steady-state is reached.

Loading Dose

This remains relatively unaltered in elderly patients.

Absorption

This is slower on average in elderly patients.

Hepatic Metabolism

This decreases in general with elderly patients.

Glomerular Filtration Rate

The study of the biochemical and physiological effects of drugs and their mechanism of action, including the relationship between the dose (or concentration) of a drug and the effect it produces.

Pharmacodynamics

Drugs that mimic the effects of endogenous ligands by interaction with the same receptors.

Agonists

Compounds that inhibit the response of a specific agonist by competition for binding sites.

Antagonist

D + R (D-R) --> E

Occupation Theory

A maximal effect can be produced by a drug when only a small proportion of receptor is occupied.

Spare-Receptor Concept

The maximum effect of a drug.

Efficacy; refers to the stimulus properties of the drug receptor complex

A comparative measure that refers to the different doses of two drugs that are needed to produce the same effect.

Potency

A drug that will generate a response that is less than maximal.

Partial Agonist

The dose causing an effect that is 50% of the maximum or a response in 50% of the population.

ED-50

The dose that is lethal (or toxic) for 50% of the population.

LD-50

Therapeutic Index

LD-50 / ED-50

Drugs that stabilize normally active receptors in an inactive conformation.

Inverse Agonist

A condition in which increasing doses of a drug are required to generate the same effect.

Tolerance

Acute tolerance (i.e. within minutes to hours)

Tachyphylaxis

The effect of genetic variation on drug response.

Pharmacogenetics

The application of genomics to the study of human variability in drug response and development of new drugs.

Pharmacogenomics

The observed characteristic of a drug (e.g. clearance or rate of metabolism).

Phenotype

A variation in the DNA sequence that is present at an allele frequency of >1% of the population.

Polymorphism

Has two defective alleles and lacks functional enzymes.

Poor Metabolizer

Heterozygous for one functional allele; has two partially defective alleles that cause reduced metabolism.

Intermediate Metabolizer

Two normal alleles.

Efficient/Extensive Metabolizer

Duplicated or multiduplicated functional alleles.

Ultra-Rapid Metabolizer

Major mediator of inflammation, anaphylaxis, and gastric acid secretion.

Histamine

Predominant storage site for histamine in most tissues.

Mast cells and Basophils (in blood)

H1 Histamine Receptor effects

Vascular and Extravascular smooth muscle, endothelial cells, glands, CNS; most abundant receptor

H2 Histamine Receptor effects

Gastric parietal cells, cardiac muscle

Triple Response

Histamine released intradermally; 1. localized red spot, 2. brighter red flush (flare), 3. a wheal that is discernible in 1-2 mins

15 steps to reduce risk of hospital infection

1. Clean hands 2. Clean stethoscope 3. Antibiotic catheter 4. Choose low infection rate surgeon 5. Prepare for surgery by showering with chlorhexidine soap (get rid of skin bugs) 6. Get tested for MRSA 7. Stop smoking 8. Remind doc that antibiotic may be needed before first incision 9. Ask doc about keeping patient warm during surgery 10. Use clippers rather than a razor for surgical site 11. Avoid touching hands to mouth, don't leave food or utensils on bed sheets 12. Monitor glucose constantly 13. Avoid UT catheter if possible, remove ASAP if used 14. Make sure IV is clean and changed every 3-4 days 15. Follow this during Cesarean surgery

Ascariasis

1. Caused by intestinal nematode 2. Acquired by ingesting contaminated vegetables and drinking-water 3. Most prevalent helminthes infection in the world