Obesity and Bariatric Surgery Pharmacokinetics Flashcards
What are the physiologic alterations in obesity?
- organ hypertrophy
- increased adipose mass
- increased lean body mass
- increased levels of alpha-1 glycoprotein
- fatty infiltration to the liver
- increased blood volume
- increased plasma lipids
- increased extracellular volume
- alterations in cardiac output
When may the use of IBW be preferred over actual bodyweight?
- drugs with low Vd estimates
- distribution favors lean bodyweight
How is the absorption of a drug affected by obesity?
- accelerated gastric emptying = increased rate of absorption
- increased cardiac output =
- alterations in enterohepatic cycling =
How is subcutaneous administration in obesity effect the absorption?
decreased, due to poor blood flow/perfusion to fat
What physiologic alterations in obesity can impact distribution?
- increased adipose tissue
- increased lean body mass
- altered plasma protein levels
- altered cardiac output
- altered tissue perfusion
- increased extracellular fluid
- altered regional blood flow
Which body weight should be used if the ratio of Vd/TBW(obese pt):Vd/TBW (nonobese pt)is ~1 or >1?
TBW
How does fatty inflitration of the liver in obesity effect metabolism?
may induce liver damage which is proportional to the degree of obesity which can cause alterations in phase I and phase II enzyme activity
Which body weight should be used if the ratio of Vd/TBW(obese pt):Vd/TBW (nonobese pt) is <1?
ideal body weight
Where does a majority of drug absorption occur?
prominal small intestine (duodenum and jejumun)
What is short bowel syndrome?
malabsorptive state caused by physical or functional loss of significant portions of the small intestine
What is intestinal failure?
intestinal function is insufficent to meet the bodys nutrition and hydration needs and supplementary parenteral nutrition and/or IV fluid is required
What are the causes of short bowel syndrome?
intestinal resection associated with Crohn’s disease, mesenteric vascular events, trauma, volvulus, malignancy, and complications with previous abdominal surgerys
common intestinal resections:
- jejuno-ileal anastomosis
- jejuno-colonic anastomosis
- end-jejunostomy
What are the pharmacokinetic considerations following resection surgery?
- post-operative gastric acid hypersecretion may impact the rate and extent of drug absorption
- gastric emptying time is accelerated and may impact the rate of drug absorption
- GI transit time may be reduced which decrease the extent of drug absorption
- surface area is reduced which reduces the extent of drug absorption
- reduce in first pass metabolism capacity affects the extent of drug absorption
- drugs that undergo enterhepatic circulation may have altered bioavaliability
What are the most common bariatric procedures?
gastric sleeve (GS) and Roux-en-Y gastric bypass (RYGB)
What are the complications associated with the RYGB procedure?
malabsorptive of nutrients and vitamins, alterations in absorption, distribution, and clearance
