Stereoselective pharmacokinetics of ibuprofen and its lysinate from suppositories in rabbits

In vivo and in vitro transdermal availability of Ibuprofen using novel solubility enhancing fluid nanosized carrier systems

The objective of this study was to explore the benefits of transdermal drug delivery systems as an alternative option for patients who are unable to tolerate oral administration of drugs, such as ibuprofen (IB). To achieve this, nonionic surfactants and three cosolvents were employed to develop new microemulsions (MEs) that contained IB as nanocarriers. The aim was to enhance the solubility and bioavailability of the drug after transdermal administration. The MEs were characterised by droplet size, polydispersity index (PDI), and rheological properties. Furthermore, the flux of IB was evaluated by Franz diffusion cells using excised rat skin and in vivo bioavailability using rats. The results showed that the MEs had ideal viscosity and droplet size below 100 nm. Moreover, using the developed MEs, an improvement in the solubility (170 mg/mL) and flux through the rat skin (94.6 ± 8.0 µg/cm2.h) was achieved. In addition, IB demonstrated a maximum plasma level of 0.064 mg/mL after 8 h of transdermal administration in rats using the ME with an increase in the bioavailability of about 1.5 times in comparison to the commercial IB gel. In conclusion, the developed nonionic MEs containing IB can be ideal nanocarriers and promising formulations for the transdermal administration of IB.

Preparation, Characterization and Pharmacokinetics Evaluation of the Compound Capsules of Ibuprofen Enteric-Coated Sustained-Release Pellets and Codeine Phosphate Immediate-Release Pellets

The objective of this study was to prepare ibuprofen enteric-coated sustained-release pellets (IB-SRPs) and codeine phosphate immediate-release pellets (CP-IRPs) to play a synergistic role in analgesia. The pellets were developed by extrusion-spheronization and fluidized bed coating technology. The single-factor investigation was used to determine the optimal prescription and process. The sustained-release membrane of IB-SRPs was water-insoluble ethyl cellulose (EC), triethyl citrate (TEC) was used as plasticizer, and hydroxypropyl methylcellulose (HPMCP) was chose as porogen. Besides, the immediate-release layer of CP-IRPs was gastric-soluble coating film. The ibuprofen and codeine phosphate compound capsules (IB-CP SRCs) were prepared by IB-SRPs and CP-IRPs packed together in capsules with the optimum doses of 200 and 13 mg, respectively. The prepared pellets were evaluated by scanning electron microscopy and dissolution test. Pharmacokinetic studies in beagle dogs indicated that the optimized IB-CP SRCs had smaller individual differences and better reproducibility comparing with commercial available tablets. Additionally, IB-CP SRCs achieved consistency with in vivo and in vitro tests. Therefore, IB-CP SRCs could play a great role in rapid and long-term analgesic.

Thermosensitive In Situ Gel Based on Solid Dispersion for Rectal Delivery of Ibuprofen

The objective of this study was to develop a thermosensitive in situ gel based on solid dispersions (SDs) for rectal delivery of ibuprofen (IBU). Thermosensitive (poloxamer 407) and mucoadhesive (hydroxypropylmethyl cellulose E5 and sodium alginate) polymers were used to prepare the in situ gel and the sol-gel transition temperature (T _sol-gel) and gel strength were optimized. The in vitro release performance and in vivo pharmacokinetic properties of the in situ gel after their rectal administration to rabbits were investigated. Compared with the solid suppository, the cumulative release of the IBU SDs loaded in situ gel was significantly increased. The in vivo pharmacokinetics indicated that in situ gel had a higher peak plasma concentration (C _max) and area under the curve (AUC_(0-∞)) in plasma than the solid suppositories. Histopathology results showed that the IBU in situ gel given at a dose of 15 mg/kg did not produce any irritation. In conclusion, this study suggested that the in situ gel could be an effective rectal formulation for IBU.

Determination of (S)-(+)- and (R)-(-)-ibuprofen enantiomers in human plasma after chiral precolumn derivatization by reversed-phase LC–ESI-MS/MS

Background: A selective, sensitive and high-throughput LC–ESI-MS/MS method has been developed and validated for the chromatographic separation and quantitation of (S)-(+)-ibuprofen and (R)-(-)-ibuprofen after derivatization with (S)-(-)-1-(1-napthyl)ethylamine using 1-hydroxybenzotriazole as the activator of the carboxylic acid group and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide as the coupling reagent in human plasma. Results: Both the analytes were chromatographically separated with a resolution factor of 1.27 on a Kinetex PFP (50 × 4.6 mm, 2.6 µm) analytical column. The method was validated over the concentration range of 0.10–32.0 µg/ml for both the enantiomers. The magnitude of matrix effect was assessed by post-column analyte infusion and also by precision (%CV) values for the calculated slopes of calibration curves. The mean extraction recovery was >91% for both the enantiomers. Conclusion: The method was successfully applied to a bioequivalence study in 34 healthy human subjects. The assay reproducibility was confirmed by reanalysis of 130 subject samples.

Development of novel ibuprofen-loaded solid dispersion with enhanced bioavailability using cycloamylose

To develop a novel ibuprofen-loaded solid dispersion with enhanced bioavailability using cycloamylose, it was prepared using spray-drying techniques with cycloamylose at a weight ratio of 1:1. The effect of cycloamylose on aqueous solubility of ibuprofen was investigated. The physicochemical properties of solid dispersions were investigated using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared with ibuprofen powder. This ibuprofen-loaded solid dispersion improved about 14-fold drug solubility. Ibuprofen was present in an unchanged crystalline state, and cycloamylose played the simple role of a solubilizing agent in this solid dispersion. Moreover, the dispersion gave 2-fold higher AUC (area under the drug concentration-time curve) value compared with a ibuprofen powder, indicating that it improved the oral bioavailability of ibuprofen in rats. Thus, the solid dispersion may be useful to deliver ibuprofen with enhanced bioavailability without crystalline change.

Enhanced Oral Bioavailability of Ibuprofen in Rats by Poloxamer Gel Using Poloxamer 188 and Menthol

To improve the oral bioavailability of poorly water-soluble ibuprofen with poloxamer and menthol, the effects of menthol and poloxamer 188 on the aqueous solubility of ibuprofen were investigated. The dissolution and pharmacokinetic study of ibuprofen delivered by the ibuprofen-loaded preparations composed of poloxamer 188 and menthol were then performed. In the absence of poloxamer, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6 followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that four parts menthol formed eutectic mixture with six parts ibuprofen. In the presence of poloxamer, the solutions with the same ratio of menthol to ibuprofen showed an abrupt increase in the solubility of ibuprofen. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2 mg/mL. The simultaneous addition of menthol and poloxamer 188 significantly improved the dissolution rates of ibuprofen from aqueous solution due to the ibuprofen solubility-improving effect of menthol in the presence of poloxamer. Furthermore, the ibuprofen-loaded preparation with menthol and poloxamer 188 gave significantly higher initial plasma concentrations, Cmax, and AUC of ibuprofen than did the preparation without menthol and poloxamer 188, indicating that the simultaneous addition of menthol and poloxamer 188 could improve the oral bioavailability of ibuprofen in rats. In modern pain management it is always desirable for the ibuprofen-loaded preparation with poloxamer 188 and menthol to show a rapid onset of action with a minimal phase of lag time to feel the decreased pain. From an industry point of view, it is more desirable for a formulation to be fast acting, easy to use, and cost effective. Thus, the ibuprofen-loaded preparation with poloxamer 188 and menthol was a more effective oral dosage form for poorly water-soluble ibuprofen.

Retarded dissolution of ibuprofen in gelatin microcapsule by cross-linking with glutaradehyde

Ibuprofen-loaded gelatin microcapsule, a solid form of microcapsules simultaneously containing ethanol and ibuprofen in water-soluble gelatin shell was previously reported to improve the dissolution of drug. In this study, to retard the initial high dissolution of ibuprofen from gelatin microcapsule, the ibuprofen-loaded cross-linked gelatin microcapsule was prepared by treating an ibuprofen-loaded gelatin microcapsule with glutaraldehyde and its dissolution was evaluated compared to ibuprofen powder and gelatin microcapsule. The ibuprofen-loaded cross-linked microcapsule treated with glutaraldehyde for 10 and 60 sec gave significantly higher dissolution rates than did ibuprofen powder. Furthermore, the dissolution rate of ibuprofen from the cross-linked microcapsule treated for 10 sec was similar to that from gelatin microcapsule. However, the dissolution rate of ibuprofen from the cross-linked microcapsule treated for 60 sec decreased significantly compared to gelatin microcapsule, suggesting that the treatment of gelatin microcapsule with glutaraldehyde for 60 sec could cross-link the gelatin microcapsule. Furthermore, the cross-linking of gelatin microcapsule markedly retarded the release rate of ibuprofen in pH 1.2 simulated gastric fluid compared to gelatin microcapsule. However, the cross-linking of gelatin microcapsule with glutaraldehyde hardly changed the size of gelatin microcapsules, ethanol and ibuprofen contents encapsulated in gelatin microcapsule. Thus, the ibuprofen-loaded cross-linked gelatin microcapsule could retard the initial high dissolution of poorly water-soluble ibuprofen.

Preparation of ibuprofen-loaded liquid suppository using eutectic mixture system with menthol

To prepare an ibuprofen-loaded liquid suppository using eutectic mixture with menthol, the effects of menthol and poloxamer 188 (P 188) on the aqueous solubility of ibuprofen were investigated. The physicochemical properties such as gelation temperature, gel strength and bioadhesive force of various formulations composed of ibuprofen, menthol and P 188 were investigated. Then, the pharmacokinetic study of ibuprofen delivered by the liquid suppositories composed of P 188 and menthol were then performed. In the absence of P 188, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6 followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that four parts of ibuprofen formed eutectic mixture with six parts of menthol. In the presence of P 188, the solutions with the same ratio showed abrupt increase in the solubility of ibuprofen. Furthermore, the solution with ratio of 4:6 showed more than 2.5- and 6-fold increase in the solubility of ibuprofen compared with that without additives and that without menthol, respectively. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2mg/ml. Ibuprofen increased the gelation temperature and weakened the gel strength and bioadhesive force of liquid suppositories. However, menthol did the opposite due to forming the eutectic mixture with ibuprofen. The ibuprofen-loaded liquid suppository [P 188/menthol/ibuprofen (15/0.25/2.5%)] with the maximum ibuprofen solubility of 1.2mg/ml was administered easily to the anus and to remain at the administered site without leakage after the dose. Furthermore, it gave significantly higher initial plasma concentrations, Cmax and AUC of ibuprofen than did solid suppository, indicating that the drug from poloxamer gel could be more absorbed than that from solid one in rats. Thus, the liquid suppository system with P 188 and menthol, a more convenient and effective rectal dosage form for ibuprofen will be expected to enhance the rectal bioavailability of ibuprofen.

Enhanced rectal bioavailability of ibuprofen in rats by poloxamer 188 and menthol

To improve the bioavailability of poorly water-soluble ibuprofen in the rectum with poloxamer and menthol, the effects of menthol and poloxamer 188 on the aqueous solubility of ibuprofen were investigated. The dissolution and pharmacokinetic study of ibuprofen delivered by the poloxamer gels composed of poloxamer 188 and menthol were then performed. In the absence of poloxamer, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6 followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that four parts menthol formed eutectic mixture with six parts ibuprofen. In the presence of poloxamer, the solutions with the same ratio of menthol to ibuprofen showed abrupt increase in the solubility of ibuprofen. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2mg/ml. Menthol improved the dissolution rates of ibuprofen from poloxamer gels. Release mechanism showed that the release rate of ibuprofen from the poloxamer gels without menthol was independent of the time but the drug might be released from the poloxamer gels with menthol by Fickian diffusion. Furthermore, the poloxamer gel with menthol (poloxamer/menthol/ibuprofen (15%/0.25%/2.5%)) gave significantly higher initial plasma concentrations, C(max) and AUC of ibuprofen than did solid suppository, indicating that the drug from poloxamer gel could be more absorbed than that from solid one in rats. Thus, the poloxamer gel with poloxamer 188 and menthol was a more effective rectal dosage form for ibuprofen.

Effects of absorption rate on the pre-systemic chiral inversion of ibuprofen in rabbits

The chiral inversion kinetics of ibuprofen was evaluated after intraduodenal administration of racemic ibuprofen in conventional powder form and sustained-released granules compared with intravenous administration in rabbits. The AUC ratios of the S-(+) and R-(-) enantiomers remained almost constant values with time up to 2 h after administration of sustained-release formulation, while those after administration of the powder increased with time. R-(-) enantiomer to S-(+) enantiomer inversion ratios after intraduodenal administration of the powder form and the sustained-release form, and after intravenous injection were calculated to be 1.63, 1.94 and 1.19, respectively, indicating that pharmacological effects may depend on the absorption rate in rabbits.

Recent applications of stereoselective chromatography

Some recent applications of stereoselective chromatography in the fields of clinical pharmacy, drug analysis, food, and natural products are reviewed. The review is documented with up-to-date literature, which will assist further expansion of research in these areas.