In the case of the majority of studied drugs , an increased absorption rate was observed early after RYGBP .
The effect on systemic exposure allows for a low degree of extrapolation , including between drugs subjected to the same major metabolic and transporter pathways .
Anatomical changes in the gastrointestinal tract and subsequent weight loss may influence drug disposition and thus drug dosing following bariatric surgery .
This review systematic ally examines the effects of bariatric surgery on drug pharmacokinetics , focusing especially on the mechanisms involved in restricting oral bioavailability .
Caffeine as a probe for CYP1A2 activity: potential influence of renal factors on urinary phenotypic trait measurements.
Two established caffeine-based urinary methods for measuring CYP1A2 activity were compared with each other , and also with the systemic clearance of caffeine which served as a st and ard of reference for such activity . Following a st and ardized dose , caffeine ( 137X ) and its metabolites were measured in urine and plasma of 39 healthy subjects . The measurements allowed determinations of : ( 1 ) systemic caffeine clearance ( CL(caff ) ) ; ( 2 ) the caffeine metabolite ratio ( AFMU + 1X + 1U)/17U determined in an overnight-urine specimen and referred to as CMR , and ( 3 ) the ratio ( 17X + 17U)/137X measured in urine collected between 4 and 5 h after caffeine intake and referred to as PCUR for ' paraxanthine-caffeine urinary ratio ' . The PCUR showed a bimodal distribution and a relatively wide variation , CL(caff ) and CMR were both normally distributed . The correlation between CL(caff ) and CMR was r = 0.77 ( p < 0.001 ) , between CLcaff and PCUR r = 0.46 ( p < 0.01 ) , and between CMR and PCUR r = 0.40 ( p < 0.02 ) . The difference between the correlation coefficients 0.77 and 0.46 was statistically significant ( z-test ; p < 0.05 ) . The well established decrease of caffeine metabolism by oral contraceptive use was observed with both CL(caff ) and CMR but not with PCUR . Examination of possible explanations for the differences between PCUR and CMR led to the finding of a correlation between PCUR and the renal clearance of caffeine ( CLr ) with r = -0.47 ( p < 0.01 ) . Further scrutiny demonstrated that a bimodal or non-normal frequency distribution as shown by PCUR was also shown by CLr and by urine flow rate . ( ABSTRACT TRUNCATED AT 250 WORDS
In the case of the majority of studied drugs , an increased absorption rate was observed early after RYGBP .
The effect on systemic exposure allows for a low degree of extrapolation , including between drugs subjected to the same major metabolic and transporter pathways .
Anatomical changes in the gastrointestinal tract and subsequent weight loss may influence drug disposition and thus drug dosing following bariatric surgery .
This review systematic ally examines the effects of bariatric surgery on drug pharmacokinetics , focusing especially on the mechanisms involved in restricting oral bioavailability .