Evaluation of sex differences in the pharmacokinetics of ranitidine in humans

Histamine H2-Receptor Antagonist Use Is Associated With Lower Prevalence of Nonalcoholic Fatty Liver Disease: A Population-based Study From the National Health and Nutrition Examination Survey, 2001-2006

BACKGROUND & AIM

Recent basic mechanistic studies found that proton-pump inhibitors (PPIs) or histamine antagonists inhibited multiple pathways involved in nonalcoholic fatty liver disease (NAFLD) development. The aim of this study was to investigate an association between PPIs or H1/H2-receptor antagonist (H1RA/H2RA) use and NAFLD prevalence in the general US population.

METHODS

We conducted a cross-sectional analysis of data from the National Health and Nutrition Examination Survey, 2001-2006. We included 10,398 adults aged 20 to 74 years who had alanine aminotransferase data; of those, 2058 were identified as having NAFLD and 8340 as controls. PPI or H1RA/H2RA use was defined as use of prescription medications in the preceding month. The length of use was categorized as ≤60 days and >60 days. NAFLD was defined as elevated serum aminotransferases without any indication of other causes of chronic liver disease.

RESULTS

In the multivariate unconditional logistic regression analysis, H2RA use was inversely associated with prevalent NAFLD [odds ratio (OR)=0.43, 95% confidence interval (CI), 0.18-0.99], a finding that was primarily limited to men (OR=0.18, 95% CI, 0.04-0.79) and those with insulin resistance (OR=0.22, 95% CI, 0.05-0.95). However, no significant associations were found between PPI or H1RA use and prevalent NAFLD.

CONCLUSIONS

These findings, from the first human study to investigate an association of PPI or H1RA/H2RA use with NAFLD, suggest that H2RA use may be associated with a lower prevalence of NAFLD, primarily among men with insulin resistance.

Pharmacokinetics of ranitidine in preterm and term neonates with gastroesophageal reflux

Background

The aim of this study was to determine the effect of gestational age on pharmacokinetics of ranitidine in newborns with gastroesophageal reflux.

Methods

A prospective, descriptive and pharmacokinetic study was carried out in 30 pre-term and 20 full-term babies. 3 mg/kg of ranitidine was administered intravenously to all the babies and at 0.25, 0.5, 1, 2, 4, and 8 h following the administration, samples of blood were drawn to assess ranitidine levels using high performance liquid chromatographic technique.

Results

Pharmacokinetics of ranitidine had a bi-exponential behavior with a half-life elimination of (t_1/2el) 2.79 h, area under curve (AUC) of 1688 ng/mL, volume of distribution (Vd) of 1.44 L/kg, and clearance (Cl) of 5.9 L/kg/h. The median plasmatic concentration in pre-terms was 1113 ng/mL and 280 ng/mL in full-terms. Vd, t1/2 and Cl presented high values in preterm although the correlation of Cl with glomerular filtration in term newborns was better.

Conclusions

Plasma levels of ranitidine depend on the gestational age of the newborns. However, the possible relationship between after-birth age and pharmacokinetics of the neonates as their internal organs get matured without minding their gestational background.

Polyethylene glycol 400 enhances the bioavailability of a BCS class III drug (ranitidine) in male subjects but not females

PURPOSE

The aim of this study was to investigate the effects of different doses of polyethylene glycol 400 (PEG 400) on the bioavailability of ranitidine in male and female subjects.

METHOD

Ranitidine (150 mg) was dissolved in 150 ml water with 0 (control), 0.5, 0.75, 1, 1.25 or 1.5 g PEG 400 and administered to 12 healthy human volunteers (six males and six females) in a randomized order. The cumulative amount of ranitidine and its metabolites excreted in urine over 24 h was determined for each treatment using a validated HPLC method.

RESULTS

In the male volunteers, the mean cumulative amount of ranitidine excreted in the presence of 0, 0.5, 0.75, 1, 1.25 and 1.5 g PEG 400 were 35, 47, 57, 52, 50 and 37 mg respectively. These correspond to increases in bioavailability of 34%, 63%, 49%, 43% and 6% over the control treatment. In the female subjects, the mean cumulative quantity of ranitidine excretion in the absence and presence of increasing amounts of PEG 400 were 38, 29, 35, 33, 33 and 33 mg, corresponding to decreases in bioavailability of 24%, 8%, 13%, 13% and 13% compared to the control. The metabolite excretion profiles followed a similar trend to the parent drug at all concentrations of PEG 400.

CONCLUSIONS

All doses of PEG 400 enhanced the bioavailability of ranitidine in male subjects but not females, with the most pronounced effect in males noted with the 0.75 g dose of PEG 400 (63% increase in bioavailability compared to control, p < 0.05). These findings have significant implications for the use of PEG 400 in drug development and also highlight the importance of gender studies in pharmacokinetics.