Studies on the Acute Toxicity, Pharmacokinetics and Pharmacodynamics of Paliperidone Derivatives - Comparison to Paliperidone and Risperidone in Mice and Rats

Hyaluronidase impacts exposures of long-acting injectable paliperidone palmitate in rodent models

A significant challenge in the development of long-acting injectable drug formulations, especially for anti-infective agents, is delivering an efficacious dose within a tolerable injection volume. Co-administration of the extracellular matrix-degrading enzyme hyaluronidase can increase maximum tolerable injection volumes but is untested for this benefit with long-acting injectable formulations. One concern is that hyaluronidase could potentially alter the tissue response surrounding an injection depot, a response known to be important for drug release kinetics of long-acting injectable formulations. The objective of this pilot study was to evaluate the impact of co-administration of hyaluronidase on the drug release kinetics, pharmacokinetic profiles, and injection site histopathology of the long-acting injectable paliperidone palmitate for up to four weeks following intramuscular injection in mouse and rat models. In both species, co-administration of hyaluronidase increased paliperidone plasma exposures the first week after injection but did not negate the overall long-acting release nature of the formulation. Hyaluronidase-associated modification of the injection site depot was observed in mice but not in rats. These findings suggest that further investigation of hyaluronidase with long-acting injectable agents is warranted.

Novel risperidone orally disintegrating minitablets for pediatric use: patient acceptance and dose adjustment

OBJECTIVE

Risperidone is a potent psychotropic agent has been approved for symptomatic treatment of irritability in children and adolescents with autism spectrum disorders. However, its bitter taste and dose adjustment of liquid dosage forms are a main hurdle for patient acceptance.

SIGNIFICANCE

Thus, this recent study investigate the formulation of taste masked risperidone orally disintegration minitablets (ODMT) as a way of enhancing patient acceptance.

METHODS

Taste masked risperidone hydrogenated castor oil or Cetyl alcohol based granules were prepared using a simple melt granulation technique in different drug to lipid ratios; drug release, bitterness score of the prepared granular formulations were evaluated. DSC was also performed to detect the possible drug lipid interaction. The selected lipid-based granules were further compressed into ODMT formulations. Bitterness score was assessed by gustatory sensation test and results were compared to marketed liquid formulations of risperidone.

RESULTS

All the prepared ODMT formulations showed high content uniformity, with minimum dose fluctuation compared to marketed oral liquid preparations.

CONCLUSION

In conclusion, risperidone lipid-based granules could be formulated in different ratios by simple techniques and commonly used excipients into taste masked risperidone ODMT with accurate and flexible doses suitable for pediatric use with high taste preference and acceptability.

Designed proteinoid polymers and nanoparticles encapsulating risperidone for enhanced antipsychotic activity

BACKGROUND

Nanoparticles (NPs) incorporating drug formulations can be used to facilitate passage through biological barriers including the blood-brain barrier (BBB) and increase drug delivery and bioavailability. Hence, NP-based administration may enhance the efficiency of current antipsychotics. Encapsulation within NPs can resolve aqueous solubility problems that not only reduce permeability through the BBB but also affect targeting. The present study describes a new drug delivery system based on proteinoid NPs to explore the possibility of improving drug efficacy. Risperidone (RSP) is a commonly used atypical antipsychotic medication, and was therefore selected for encapsulation by proteinoid NPs.

RESULTS

Proteinoid polymers with high molecular weight and low polydispersity were synthesized from L-amino acids and poly-L-lactic acid (PLLA) by thermal step-growth polymerization mechanism. RSP-loaded proteinoid NPs were then prepared using a self-assembly process in the presence of RSP, followed by PEGylation. The optimal PEGylated RSP-loaded NPs were characterized in terms of diameter and size distribution, drug loading, ζ-potential, cytotoxicity, biodistribution, and psychopharmacological effects. The findings indicate significantly higher antipsychotic activity of drug-loaded proteinoid NPs compared to free RSP.

CONCLUSIONS

Proteinoid NPs enhance RSP delivery and may potentially increase drug efficiency by reducing dosage and side effects.

Proteinoid Nanocapsules as Drug Delivery System for Improving Antipsychotic Activity of Risperidone

Risperidone (RSP) is an atypical antipsychotic drug widely used to treat schizophrenia and bipolar disorder. Nanoparticles (NPs) are being developed as in vivo targeted drug delivery systems, which cross the blood-brain barrier and improve pharmacokinetics and drug effectiveness. Here, biodegradable proteinoids were synthesized by thermal step-growth polymerization from the amino acids l-glutamic acid, l-phenylalanine and l-histidine and poly (l-lactic acid). Proteinoid NPs containing RSP were then formed by self-assembly, overcoming the insolubility of the drug in water, followed by PEGylation (poly ethylene glycol (PEG) conjugation to increase the stability of the NPs in the aqueous continuous phase. These NPs are biodegradable owing to their peptide and ester moieties. They were characterized in terms of diameter, size distribution, drug loading, and long-term storage. Behavioral studies on mice found enhanced antipsychotic activity compared to free RSP.

New Approach in Ulcer Prevention and Wound Healing Treatment using Doxycycline and Amoxicillin/LDH Nanocomposites

Doxycycline (DOX) and amoxicillin (AMOX) are important Broad-spectrum antibiotics used in treating multiple human and animal diseases. For the sake of exploring novel medical applications, both antibiotics were loaded into magnesium aluminium layer double hydroxide (Mg-Al)/LDH nanocomposite through the co-precipitation method. The synthesized materials were characterized by XRD, FT-IR, particle size analysis, FESEM and HRTEM. Acute toxicological studies were conducted using median lethal dose LD50, where a total number of 98 rats (200-150 gm) of both sexes were used. An experimental wound was aseptically incised on the anterior-dorsal side of each rat, while 98% of pure medical ethanol was used for ulcer induction. Acute toxicity, wound closure rate, healing percentages, ulcer index, protective rate and histopathological studies were investigated. Antibiotic Nanocomposites has significantly prevented ulcer formation and improved wound healing process to take shorter time than that of the typical processes, when compared with that of same drugs in microscale systems or commercial standard drugs. These results were confirmed by the histopathological findings. By converting it into the Nanoform, which is extremely important, especially with commonly used antibiotics, novel pharmacological properties were acquired from the antibiotics. The safe uses of DOX/LDH and AMOX/LDH Nanocomposites in this study were approved for biomedical applications.

Physiologically Based Modeling Approach to Predict Dopamine D2 Receptor Occupancy of Antipsychotics in Brain: Translation From Rat to Human

Receptor occupancy (RO) is a translational biomarker for assessing drug efficacy and safety. We aimed to apply a physiologically based pharmacokinetic (PBPK) modeling approach to predict the brain dopamine D2 RO time profiles of antipsychotics. Clozapine and risperidone were modeled together with their active metabolites, norclozapine and paliperidone, First, in PK‐Sim a rat PBPK model was developed and optimized using literature plasma PK data. Then, blood‐brain barrier parameters including the expression and efflux transport kinetics of P‐glycoprotein were optimized using literature microdialysis data on brain extracellular fluid (brainECF), which were further adapted when translating the rat PBPK model into the human PBPK model. Based on the simulated drug and metabolite concentrations in brainECF, drug‐D2 receptor binding kinetics (association and dissociation rates) were incorporated in MoBi to predict RO. From an extensive literature search, 32 plasma PK data sets (16 from rat and 16 from human studies) and 23 striatum RO data sets (13 from rat and 10 from human studies) were prepared and compared with the model predictions. The rat PBPK‐RO model adequately predicted the plasma concentrations of the parent drugs and metabolites and the RO levels. The human PBPK‐RO model also captured the plasma PK and RO levels despite the large interindividual and interstudy variability, although it tended to underestimate the plasma concentrations and RO measured at late time points after risperidone dosing. The developed human PBPK‐RO model was successfully applied to predict the plasma PK and RO changes observed after risperidone dose reduction in a clinical trial in schizophrenic patients.

Butyl stearate prolongs the drug release period of isoperidone‑loaded poly (lactic‑co‑glycolic acid) microspheres: In vitro and in vivo investigation

The present study aimed to investigate the effects of butyl stearate on t-butoxyl paliperidone derivative (isoperidone)-loaded poly(lactide-co-glycolide) (PLGA) microspheres. The mechanism of drug release rate delay by butyl stearate was examined by accelerated testing, morphological observation, thermal and fluorescence analyses. In vivo pharmacokinetic study was conducted on female beagle dogs. Spherical microspheres with smooth surfaces, small internal pores and shell structures were initially prepared. It was found that 3% (w/w) butyl stearate prolonged the in vitro drug release period from 46 to 82 days, and in vivo release period from 20 to 27 days. Furthermore, the results demonstrated that the green fluorescence imaging of isoperidone approaching the cores of microspheres with 3% butyl stearate was brighter than in microspheres without additives. In conclusion, it was shown that butyl stearate affected the microsphere structure, isoperidone microsphere distribution and isoperidone crystallinity. The results of the present study thus provide a potential method to develop sustained-release preparations.

Paliperidone-loaded spherical solid lipid nanoparticles

Gelucire® 50/13, a macrogol glyceride, was used as a surfactant for the preparation and stabilization of paliperidone-loaded Capmul® GMS-50K matrix-based solid lipid nanoparticles (SLNs). The homogeneously distributed paliperidone did not affect the crystal structure of the lipid matrix in the SLNs.

Paliperidone extended-release: does it have a place in antipsychotic therapy?

Paliperidone (9-hydroxy-risperidone), the active metabolite of risperidone, was approved for treating schizophrenia worldwide in 2006 as paliperidone extended-release (PER), and became the first second-generation antipsychotic specifically licensed for treating schizoaffective disorder in 2009. However, at the same time, its comparatively high cost gave rise to concerns about the cost-effectiveness of PER as compared with its precursor, risperidone. This paper reviews the existing knowledge of the pharmacology, kinetics, efficacy, tolerability, and fields of application of PER, and compares PER with risperidone in order to determine whether it has a place in antipsychotic therapy. An independent assessment of all relevant publications on PER published until July 2010 was undertaken. PER has a unique pharmacological profile, including single dosing, predominantly renal excretion, low drug-drug interaction risk, and differs from risperidone in terms of mode of action and pharmacokinetics. High-level evidence suggests that PER is efficacious and safe in schizophrenia, schizoaffective disorder, and acute manic episodes. There is a striking lack of published head-to-head comparisons between PER and risperidone, irrespective of indication. Low-level evidence shows a lower risk for hyperprolactinemia and higher patient satisfaction with PER than with risperidone. PER adds to the still limited arsenal of second-generation antipsychotics. In the absence of direct comparisons with risperidone, it remains difficult to come to a final verdict on the potential additional therapeutic benefits of PER which would justify its substantially higher costs as compared with risperidone. However, in terms of pharmacology, the available evidence cautiously suggests a place for PER in modern antipsychotic therapy.