Pharmacology for APNs Study Guide
Understand the following concepts:
Pharmacokinetics / Pharmacodynamics- you do NOT have to do any calculations!
· Define and understand the concepts of: pharmacokinetics, pharmacodynamics, pharmacology, pharmacotherapeutics, toxicology, legend drug vs OTC drug
Pharmacokinetics- the actions of the body on the drug. Pharmacokinetic process governs the absorption, distribution, and elimination of drugs. Katzung pg 5
Pharmacodynamic -the actions of the drug on the body. Katzung pg 5
Pharmacology- the study of substances that interact with living systems through chemical processes. These interactions usually occur by binding of the substance to regulatory molecules and activating or inhibiting normal body processes. These substances may be chemicals administered to achieve a beneficial therapeutic effect on
some process within the patient or for their toxic effects on regulatory processes in parasites infecting the patient. Katzung pg 1
Pharmacotherapeutics- therapeutic uses and effects of drugs.
Toxicology- is the branch of pharmacology that deals with the undesirable effects of chemicals on living systems. Katzung pg 1
All substances have the potential for toxicity. Legend drug vs OTC drug
Legend drug- is a drug, by law, can be obtained only by prescription.
OTC drug- sold directly to consumer without prescription.
· Understand the different ways drugs are classified- By sources- (derived from plant – chemical- animal), chemical structure & receptor type (beta- agonists, calcium channel antagonists etc.) pharmacotherapeutic category/classification (antihypertensives, antimicrobials etc.
· Pharmacokinetics: understand concepts of Absorption, Distribution, Metabolism, Elimination
Absorption- Entry of pharmacologic agents into plasma.
Distribution- agents leave bloodstream and distribute to interstitial and intracellular fluids.
Metabolism- Agent must be metabolized via liver, kidney or other tissue.
Elimination- Agent metabolites must be eliminated from the body (urine, bile, feces.)
-powerpoint
· Understand concepts of pharmacodynamics - Physiologic effect, Mechanism
of action- Drug concentration at site of action → pharmacologic effect → clinical response → effectiveness or toxicity. · Know the what factors impact drug absorption
Factors that affect drug absorption may be lack of absorption from the gut. Other drugs are either too hydrophilic or too lipophilic to be absorbed easily, and their low bioavailability is also doe to incomplete absorption. If too hydrophilic, the drug cannot cross the lipid cell membrane; if too lipophilic, the drug is not soluble enough to cross the water layer adjacent to the cell. Drugs may not be absorbed because of a reverse transporter associated with P-glycoprtein. This process actively pumps drugs out of gut wall cell back into gut lumen. Inhibition of P-glycoprotein and gut wall metabolism, ex grapefruit juice, may be associated with substantially increase drug absorption. Katzung
pg 47
Factors influencing GI absorption Blood flow, intestinal blood flow > stomach blood flow.
pH, especially with H2 receptor blocker or proton pump inhibitors (PPI).
Intestinal surface area (microvilli), 1000x more than stomach.
Contact time with absorptive surface; Variables, rapid vs slow GI transport, Parasympathetic input- increase rate of gastric emptying, Sympathetic input- delay gastric emptying, food→ delay absorption. Power point · Concept of bioavailability - relationship between drug route and bioavailabilty
Bioavailability is defined as the fraction of unchanged drug reaching the systemic circulation following administration by any route. For an IV dose, bioavailability is assumed to be equal to unity, 100%. For PO route bioavailability is less than 100% for two reasons- incomplete extent of absorption across the gut wall and first-pass elimination by the liver. Katzung pg 47
· What are the physiologic variables in absorption and distribution
· Know the chemical properties of drugs that affect absorption and distribution
Chemical properties
Solubility, hydrophilic (lipophobic), or lipophilic (hydrophobic).
Chemical nature- pH and pKa
Molecular weight
Partition coefficient - the ratio of lipid solubility to aqueous solubility. The higher the partition coefficient, the more membrane soluble is the substance. Powerpoint
· Concept of volume of distribution (Vd)
Hypothetical volume of fluid into which a drug is dispersed. Volume of distribution relates the amount of drug in the body to the concentration of drug in blood or plasma.
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