Conjugation reactions associated with phase II enzymes:
Substrates for these reactions usually require the presence of oxygen e.g. hydroxyl or epoxide, nitrogen or sulfur atoms.
If a drug undergoes a conjugation reaction, The conjugated form of the original drug has limited biological effects given that it typically is unable to bind to its receptor.
Both
Neither
An example of the conjugation reaction important clinically in the case of neonates: neonates may be unable to fully support conjugation reactions. For example, UDP-glucuronyltransferase enzyme activity is required for conjugating bilirubin in the liver and promoting its excretion. Neonates exhibit comparative enzyme deficiency of the time of birth and as a consequence there is a higher risk of neonatal jaundice. Neonatal jaundice is due to elevated unconjugated bilirubin levels.
True
False
Unconjugated bilirubin:
Water insoluble; highly lipophilic
May cause neonatal brain damage In the form of bilirubin encepalopathy or kernicterus.
Both
Neither
Neonatal hyperbilirubinemia (unconjugated):
Phototherapy promotes conversion of circulating bilirubin to a form that is easier to excrete.
Administration of small barbiturate doses (phenobarbital) increases the concentration of UDP glucouronosyltransferase, the enzyme activity of which decreases unconjugated bilirubin serum levels.
Both
Neither
The most important consequence of drug metabolism is promotion of renal drug excretion.
True
False
Excretion of drug-glucuronide conjugates
Renal
Biliary secretion with subsequent access to the duodenum (by way the bile duct) with ultimate excretion in the feces.
Both
Neither
The metabolic transformation of codeine into morphine is associated with a notable increase in analgesic effect.
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Source Material:
Buxton ILO Chapter
2: Pharmcokinetics: The Dynamics of Drug Absorption,
Distribution, Metabolism, and Elimiation in Goodman & Gilman's:
The Pharmacological Basis of Therapeutics, 14e, (Brunton LL H
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Gonzalez FJ
Coughtrie M Chapter 5: Drug Metabolism in Goodman & Gilman's:
The Pharmacological Basis of Therapeutics, 14e, (Brunton LL H
Knollmann BC, eds) McGraw-Hill Education, 2023.
Holford NHG Chapter
3: Pharmacokinetics & Pharmacodynamics: Rational Dosing &
the Time Course of Drug Action: in Basic & Clinical
Pharmacology (Katzung BG, Editor; Vanderah TW, Associate
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Correia MA Chapter 4
Drug Biotransformation in Basic &
Clinical Pharmacology (Katzung BG, Editor; Vanderah TW, Associate
editor) 15e McGraw Hill 2021.
Baca QJ Golan DE
Pharmacokinetics Chapter 3: Principles of Pharmacology:
The Pathophysiologic Basis of Drug Therapy. (Golan DE, editor-in
chief, Armstrong EJ Armstrong AW, associate editors) 4e Wolters
Kluwer 2017.
Guengerich FP
Chapter 4: Drug Metabolism in
Principles of Pharmacology: The Pathophysiologic Basis of Drug Therapy. (Golan DE, editor-in
chief, Armstrong EJ Armstrong AW, associate editors) 4e Wolters
Kluwer 2017.
Flood P Shafer SL
Chapter 2 Basic Principles of Pharmacology in Stoelting's
Pharmacology & Physiology in Anesthetic Practice (Glood P
Rathmell JP Urman RD, eds) 6e Wolters Kluwer 2022.
Burchum JR Rosenthal
LD Lehne's Pharmacology for Nursing Care Unit II Chapter 4
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