Mathematical modeling of oral absorption and bioavailability of a fluoroquinolone after its precipitation in the gastrointestinal tract

Effect of excipients on oral absorption process according to the different gastrointestinal segments

INTRODUCTION

Excipients are necessary to develop oral dosage forms of any Active Pharmaceutical Ingredient (API). Traditionally, excipients have been considered inactive and inert substances, but, over the years, numerous studies have contradicted this belief. This review focuses on the effect of excipients on the physiological variables affecting oral absorption along the different segments of the gastrointestinal tract. The effect of excipients on the segmental absorption variables are illustrated with examples to help understand the complexity of predicting their in vivo effects.

AREAS COVERED

The effects of excipients on disintegration, solubility and dissolution, transit time, and absorption are analyzed in the context of the different gastrointestinal segments and the physiological factors affecting release and membrane permeation. The experimental techniques used to study excipient effects and their human predictive ability are reviewed.

EXPERT OPINION

The observed effects of excipient in oral absorption process have been characterized in the past, mainly in vitro (i.e. in dissolution studies, in vitro cell culture methods or in situ animal studies). Unfortunately, a clear link with their effects in vivo, i.e. their impact on Cmax or AUC, which need a mechanistic approach is still missing. The information compiled in this review leads to the conclusion that the effect of excipients in API oral absorption and bioavailability is undeniable and shows the need of implementing standardized and reproducible preclinical tools coupled with mechanistic and predictive physiological-based models to improve the current empirical retrospective approach.

Recommended antibiotic prophylaxis regimen in retrograde intrarenal surgery: evidence from a randomised controlled trial

OBJECTIVE

To study the incidence of postoperative systemic inflammatory response syndrome (SIRS) following different antibiotic prophylaxis (ABP) regimens in retrograde intrarenal surgery (RIRS).

PATIENTS AND METHODS

Single-centre, randomised, controlled trial (August 2014-September 2017) including 426 patients with renal stones with preoperative sterile urine managed by RIRS (ClinicalTrials.gov NCT02304822). Different ciprofloxacin-based ABP regimens were used and included a zero dose, single dose (30 min before surgery) or two doses (first dose at 30 min before RIRS and additional dose within 6 h after RIRS). The incidence of SIRS was compared using intention-to-treat (ITT) and per-protocol (PP) analyses.

RESULTS

Each group enrolled 142 patients. In the ITT analysis, a zero dose of ABP was statistically similar to the two ABP regimes for the incidence of SIRS (9.9% vs single dose 4.9%, P = 0.112; vs two doses 4.2%, P = 0.062). There were also no relevant differences across groups in the PP analysis; no urosepsis was recorded. In subgroup analysis with stratification by stone area, the three regimens all had a low and similar incidence of SIRS for stones of ≤200 mm² in the ITT analysis with a sufficient power value (5.4% vs 6.2% vs 3.6%, P = 0.945 vs single dose and P = 0.553 vs two doses). However, there was a greater chance of SIRS in patients who received no ABP with stones of >200 mm² (18% vs single dose 4.3%, P = 0.036; vs two doses 5.5%, P = 0.044). Similar trends were seen in the PP analysis.

CONCLUSIONS

For patients with preoperative sterile urine, ABP is not strongly recommended in patients with stones of ≤200 mm² , but for stones >200 mm² single-dose ABP is still required.

Antibiotic prophylaxis in ureteroscopic lithotripsy: a systematic review and meta-analysis of comparative studies

OBJECTIVE

To explore the efficacy of antibiotic prophylaxis and the different strategies used to prevent infection in ureteroscopic lithotripsy (URL) by conducting a systematic review and meta-analysis.

MATERIALS AND METHODS

A systematic literature search using Pubmed, Embase, Medline, the Cochrane Library, and the Chinese CBM, CNKI and VIP databases was performed to find comparative studies on the efficacy of different antibiotic prophylaxis strategies in URL for preventing postoperative infections. The last search was conducted on 25 June 2017. Summarized unadjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the efficacy of different antibiotic prophylaxis strategies.

RESULTS

A total of 11 studies in 4 591 patients were included in this systematic review and meta-analysis. No significant difference was found in the risk of postoperative febrile urinary tract infections (fUTIs) between groups with and without antibiotic prophylaxis (OR: 0.82, 95% CI 0.40-1.67; P = 0.59). Patients receiving a single dose of preoperative antibiotics had a significantly lower risk of pyuria (OR: 0.42, 95% CI 0.25-0.69; P = 0.0007) and bacteriuria (OR: 0.25, 95% CI 0.11-0.58; P = 0.001) than those who did not. Intravenous antibiotic prophylaxis was not superior to single-dose oral antibiotic prophylaxis in reducing fUTI (OR: 1.00, 95% CI 0.26-3.88; P = 1.00).

CONCLUSIONS

We concluded that preoperative antibiotic prophylaxis did not lower the risk of postoperative fUTI, but a single dose could reduce the incidence of pyuria or bacteriuria. A single oral dose of preventive antibiotics is preferred because of its cost-effectiveness. The efficacy of different types of antibiotics and other strategies could not be assessed in our meta-analysis. Randomized controlled trials with a larger sample size and more rigorous study design are needed to validate these conclusions.

Tailoring of alginate-gelatin microspheres properties for oral Ciprofloxacin-controlled release against Pseudomonas aeruginosa

CONTEXT

Ciprofloxacin (Cip) is a broad spectrum antibiotic frequently used in the treatment of infectious diseases caused by Pseudomonas aeruginosa. Cip oral administration is commonly associated with poor drug biodisponibility, gastrointestinal tract irritation, and toxic undesirable side effects.

OBJECTIVE

The aim of this work is to provide an oral biopolymeric system for controlled release of Cip.

MATERIALS AND METHODS

Alginate-gelatin blend microspheres were crosslinked in the presence of 1,2-propylene glycol, calcium, and glutaraldehyde. Studies of Cip encapsulation and release were performed. Matrix characteristics were studied simultaneously by optical microscopy and Fourier transform infrared spectroscopy (FTIR) using synchrotron light, and by texturometric analysis. Microsphere surface topologies were observed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and epifluorescence microscopy.

RESULTS

Microspheres crosslinked with glutaraldehyde showed about 80% Cip encapsulation and less than 10% Cip release under simulated gastric conditions in 15 min, while a controlled release profile was observed at intestinal environment conditions. Antimicrobial activity against P. aeruginosa showed an increasing bacterial growth inhibition in time. Finally, bovine serum albumin (BSA) was used as model protein for binding of macromolecules onto active surface of microspheres, with a consequently modulation of Cip release.

DISCUSSION AND CONCLUSIONS

The results are indicating that alginate/gelatin matrix crosslinked via Ca(2+) and glutaraldehyde can be tailored by decorating the microsphere surface with biological active molecules useful for targeting, making a potential tool to improve Cip oral administration for infection diseases.