Preparation and In Vitro Release of Dual-Drug Resinates Containing Equivalent Content Dextromethorphan and Diphenhydramine

Improvement of drug loading onto ion exchange resin by cyclodextrin inclusion complex

CONTEXT

Ion exchange resins have ability to exchange their counter ions for ionized drug in the surrounding medium, yielding "drug resin complex." Cyclodextrin can be applied for enhancement of drug solubility and stability.

OBJECTIVE

Cyclodextrin inclusion complex of poorly water-soluble NSAIDs, i.e. meloxicam and piroxicam, was characterized and its novel application for improving drug loading onto an anionic exchange resin, i.e. Dowex® 1×2, was investigated.

METHODS

β-Cyclodextrin (β-CD) and hydroxypropyl β-cyclodextrin (HP-β-CD) were used for the preparation of inclusion complex with drugs in solution state at various pH. The inclusion complex was characterized by phase solubility, continuous variation, spectroscopic and electrochemistry methods. Then, the drug with and without cyclodextrin were equilibrated with resin at 1:1 and 1:2 weight ratio of drug and resin.

RESULTS AND DISCUSSION

Solubility of the drugs was found to increase with increasing cyclodextrin concentration and pH. The increased solubility was explained predominantly due to the formation of inclusion complex at low pH and the increased ionization of drug at high pH. According to characterization studies, the inclusion complex was successfully formed with a 1:1 stoichiometry. The presence of cyclodextrin in the loading solution resulted in the improvement of drug loading onto resin.

CONCLUSIONS

Enhancing drug loading onto ion-exchange resin via the formation of cyclodextrin inclusion complex is usable in the development of ion-exchange based drug delivery systems, which will beneficially reduce the use of harmful acidic or basic and organic chemicals.

Preparation and in vitro release of dual-drug resinate complexes containing codeine and chlorpheniramine

OBJECTIVE

To develop the dual-drug resinate complexes containing codeine and chlorpheniramine with a novel batch processing, characterize the dual-drug resinate complexes, and study its drug release behavior in vitro.

METHODS

A procedure of simultaneous dual-drug loading using combination solutions composed of different proportions of codeine phosphate and chlorpheniramine maleate was performed to achieve the specific resinate, and the dual-drug loading content was determined by high-performance liquid chromatography method. The dual-drug resinate complexes were characterized by a scanning electron microscope, and the formation mechanisms were confirmed with X-ray diffraction analyses and differential scanning calorimetric analyses. The release behavior of the two drugs from the dual-drug resinate complexes in vitro was studied in the media simulating in vivo environments (simulated gastric fluid: pH = 1.2 HCl, simulated in vivo ionic strength: 0.15 M NaCl, and simulated intestinal fluid: pH = 6.8 buffer solution containing KH2PO4-NaOH).

RESULTS

Scanning electron microscopic analyses proved that the dual-drug resinate complexes had the same appearance and characters as the initiative ion exchange resins (IERs). Via X-ray diffraction and differential scanning calorimetric analyses, it is found that the two drugs in dual-drug resinate complexes were combined with IERs by chemical bond. The drug-resinate complex, like IER, was in amorphous state. More than 90% of codeine phosphate was released in 15 minutes in three different media, whereas little amount of chlorpheniramine maleate was released in all the release time in the medium pH = 1.2 HCl, and the release equilibrium time was about 5 minutes, only 40% was released in the medium 0.15 M NaCl, and the equilibrium time was 40 minutes, and about 90% was released in the medium pH = 6.8 KH2PO4-NaOH. The increased ionic strength generally accelerated the release of the two drugs from the dual-drug resinate complexes.

CONCLUSION

The dual-drug resinate complexes were formed through the reaction between the drugs and the IERs by chemical bond. The release behavior of the drug from the dual-drug resinate complexes in vitro was mainly correlated with the drug molecular structure, the eluting ionic strength, composition, and ionic strength of the release media. The novel dual-drug resinate complexes could be used to deliver two drugs in one therapeutic dose.

Preparation of Codeine-Resinate and Chlorpheniramine-Resinate Sustained-Release Suspension and its Pharmacokinetic Evaluation in Beagle Dogs

Using ion exchange resins (IERs) as carriers, a dual-drug sustained release suspension containing codeine, and chlorpheniramine had been prepared to elevate drug safety, effectiveness and conformance. The codeine resinate and chlorpheniramine resinate beads were prepared by a batch process and then impregnated with Polyethylene glycol 4000 (PEG 4000), respectively. The PEG impregnated drug resinate beads were coated with ethylcellulose as the coating polymer and di-n-butyl-phthalate as plasticizer in ethanol and methylene chloride mixture by the Wurster process. The coated PEG impregnated drug resinate beads were dispersed in an aqueous suspending vehicle containing 0.5% w/w xanthan gum and 0.5% w/w of hydroxypropylmethylcellulose of nominal viscosity of 4000 cps, obtaining codeine resinate and chlorpheniramine resinate sustained-release suspension (CCSS). Codeine phosphate and chlorpheniramine maleate were respectively loaded onto AMBERLITE IRP 69, and PEG 4000 was used to impregnate drug resinate beads to maintain their geometry. Ethylcellulose with di-n-butyl-phthalate in ethanol and methylene chloride mixture for the coating of drug resinate beads was performed in Glatt fluidized bed coater, where the coating solution flow rate was 8-12 g/min, the inlet air temperature was 50-60 degrees C, the outlet air temperature was 32-38 degrees C, the atomizing air pressure was 2.0 bar and the fluidized air pressure was adjusted as required. Few significant agglomeration of circulating drug resinate beads was observed during the operation. The film weight gained 20% w/w and 15% w/w were suitable for the PEG impregnated codeine resinate and chlorpheniramine resinate beads, respectively. Residual solvent content increased with coating level, but inprocess drying could reduce residual solvent content. In the present study, the rates of drug release from both drug resinate beads were measured in 0.05 M and 0.5M KCl solutions. The increased ionic strength generally accelerated the release rate of both drugs. But the release of codeine from its resinate beads was much more rapid than chlorpheniramine released from its resinate beads in the same ionic strength release medium. The drug release specification of the CCSS, where release mediums were 0.05 M KCl solution for codeine and 0.5 M KCl solution for chlorpheniramine, was established to be in conformance with in vivo performance. Relative bioavailability and pharmacokinetics evaluation of the CCSS, using commercial immediate-release tablets as the reference preparation, were performed following a randomized two-way crossover design in beagle dogs. The drug concentrations in plasma were measured by a validated LC-MS/MS method to determine the pharmacokinetic parameters of CCSS. This LC-MS/MS method demonstrated high accuracy and precision for bioanalysis, and was proved quick and reliable for the pharmacokinetic studies. The results showed that the CCSS had the longer value of Tmax and the lower value of Cmax, which meant an obviously sustained release effect, and its relative bioavailability of codeine and chlorpheniramine were (103.6 +/- 14.6)% and (98.1 +/- 10.3)%, respectively, compared with the reference preparation. These findings indicated that a novel liquid sustained release suspension made by using IERs as carriers and subsequent fluidized bed coating might provide a constant plasma level of the active pharmaceutical ingredient being highly beneficial for various therapeutic reasons.

Effect of a pharmaceutical cationic exchange resin on the properties of controlled release diphenhydramine hydrochloride matrices using Methocel K4M or Ethocel 7cP as matrix formers

This work was aimed at evaluating the effect of a pharmaceutical cationic exchange resin (Amberlite IRP-69) on the properties of controlled release matrices using Methocel K4M (HPMC) or Ethocel 7cP (EC) as matrix formers. Diphenhydramine hydrochloride (DPH), which was cationic and water soluble, was chosen as a model drug. HPMC- and EC-based matrices with varying amounts (0-40%w/w) of resin incorporation were prepared by a direct compression. Matrix properties including diameter, thickness, hardness, friability, surface morphology and drug release were evaluated. The obtained matrices were comparable in diameter and thickness regardless of the amount of resin incorporation. Increasing the incorporated resin decreased the hardness of HPMC- and EC-based matrices, correlating with the degree of rupturing on the matrix surfaces. The friability of HPMC-based matrices increased with increasing the incorporated resin, corresponding to their decreased hardness. In contrast, the EC-based matrices showed no significant change in friability in spite of decreasing hardness. The incorporated resin differently influenced DPH release from HPMC- and EC-based matrices in deionized water. The resin further retarded DPH release from HPMC-based matrices due to the gelling property of HPMC and the ion exchange property of the resin. In contrast, the release from EC-based matrices initially increased because of the disintegrating property of the resin, but thereafter declined due to the complex formation between released drug and dispersed resin via the ion exchange process. The release in ionic solutions was also described. In conclusion, the incorporated resin could alter the release and physical properties of matrices.

Wet granulation as innovative and fast method to prepare controlled release granules based on an ion‐exchange resin

The goal of this work was to evaluate the suitability of wet granulation as an innovative and fast method for the preparation of granules containing a drug-resin complex (resinate), having cholestyramine as resin and potassium diclofenac (KD) as drug. Resinate and granules were prepared directly by steam granulation in high shear mixer (method A), using two different amount of resin (granules 1 and 2). For comparison granules 1 were also prepared by conventional batch method followed by steam granulation (method B). All granules showed quite irregular shape, main size fractions between 75 and 500 microm, good flowability and uniform KD distribution. Granules 1A exhibited controlled release profiles at pH 7.4, while granules 2A showed a burst effect due to KD free crystals. FT-IR studies confirmed the complete complexation between resin and KD during the granulation process with method A for granules 1. Finally, the dissolution test of granules 1A in different media revealed a controlled drug release in 12 h, providing the utility of this system for enteric drug delivery. Granules 1B evidenced similar characteristics to those of granules 1A; the drawback of the multistep procedure was related to the long processing time.

The pH-controlled dual-drug release from mesoporous bioactive glass/polypeptide graft copolymer nanomicelle composites

Dual-drug delivery systems are investigated for combined therapy with drugs having distinct therapeutic effects. However, the majority of current dual-drug delivery systems are designed for simultaneous release of two different drugs; the release of each individual drug cannot be controlled. In this study, we have demonstrated a novel dual-drug delivery system based on mesoporous bioactive glass/polypeptide graft copolymer nanomicelle composites. Water-soluble gentamicin and fat-soluble naproxen were used as model drugs in the study of this system. A pH-controlled release of individual drugs was achieved by the predominant release of gentamicin from mesoporous bioactive glass in an acid environment and fast release of naproxen in an alkaline environment from polypeptide nanomicelles. Our results suggest that the mesoporous bioactive glass/PBLG-g-PEG nanomicelle composites can be used as a dual-drug delivery system, and that the individual drug release can be controlled by the pH of the surrounding environment.