A 28-year-old man with a 10-year history of ulcerative colitis undergoes total proctocolectomy with ileostomy after an acute perforation. Three weeks postoperatively, he is started on propranolol 80 mg orally twice daily for essential tremor. His family reports that unlike his previous treatment with intravenous propranolol in the hospital, the oral medication produces minimal reduction in his tremor. Laboratory studies show normal creatinine and liver function tests. Serum propranolol levels are significantly lower than expected for his oral dose. Which of the following pharmacokinetic parameters best explains the reduced clinical effect observed in this patient?

1. A)Decreased volume of distribution due to reduced total body water
2. B)Decreased bioavailability secondary to reduced intestinal absorption surface areaGABARITO
3. C)Decreased half-life resulting in rapid drug elimination
4. D)Decreased hepatic clearance due to portosystemic shunting
5. E)Increased first-pass metabolism by residual colonic tissue