Comparison of the stability of split and intact gabapentin tablets

[Prescription of split doses in a nursing home: Contribution of an automated dose-dispensing machine]

OBJECTIVES

The territorial pharmacy of the West of Paris carries out an automated dose dispensing for a nursing home. The machine overpacks dry oral forms in unit doses and dispenses them in named pillboxes. Tablets prescribed in fractions are currently dispensed in whole unit doses, fractioned in advance by a nurse, then administered by a caregiver. These operations present a number of risks, including a break in dose identification right through to administration. The objective was therefore to extend the automated dose dispensing to split tablets by repackaging.

METHODS

The development of this new process, its software qualification and its evaluation after six months of routine use are described.

RESULTS

This process is composed of three steps, secured by pharmaceutical controls: manual production of fractions in the preparatory area, automated repackaging using a barrel and automated dispensing in pillboxes. In total, 2000 fractions were produced in six months with a non-compliance rate lower than 5% and a negligible financial loss. Following the assumption of this activity by the pharmacy, the care team declares themselves satisfied by the gain in time and safety.

CONCLUSIONS

Automated dispensing of unit doses in fractions ensures identification of the dose from prescription to administration, thus limiting administration errors.

Concerns regarding tablet splitting: a systematic review

BACKGROUND

Tablet splitting can provide dose flexibility and cost savings; however, pharmaceutical representatives typically discourage the practice.

AIM

To identify and summarise all published concerns related to tablet splitting and to present the experimental evidence that investigates those concerns.

DESIGN & SETTING

Systematic review and qualitative synthesis of tablet-splitting concerns and evidence.

METHOD

Medline and EMBASE databases were searched over all years of publication for articles in English discussing the splitting of tablets. Eligible articles included original research, narrative reviews, systematic reviews, and expert opinion.

RESULTS

After removing duplicates, 1837 potentially relevant articles underwent dual review, whereupon 1612 articles were excluded based on title and abstract. After examination of 225 full texts, 138 articles were included (one systematic review, four narrative reviews, 101 original research articles, and 32 opinion articles). The described concerns included difficulty breaking tablets, loss of mass, weight variability, chemical instability, overly rapid dosing if sustained-release medications are split, non-compliance, and patient confusion resulting in medication errors. No substantive evidence was found to support concerns regarding loss of mass, weight variability, chemical instability, or non-compliance. Evidence does support some older adults struggling to split tablets without tablet splitters, and the inappropriateness of splitting sustained-release preparations, given the potential for alteration of the rate of drug release for some products.

CONCLUSION

With the exception of sustained-release tablets, which should not be split, and excepting those older people who may struggle to split tablets based on physical limitations, there is little evidence to support tablet-splitting concerns.

The subdivision behavior of polymeric tablets

The subdivision behavior of polymeric tablets produced with the well-known polymers Soluplus® (SOL), polyvinyl pyrrolidone co-vinyl acetate (PVPVA) and hydroxypropyl methylcellulose (HPMC) was evaluated in this study. The polymeric tablets were submitted to different post-treatments (aging, thermal and exposure to compressed gaseous carbon dioxide) and its mechanical, spectroscopic and microstructure properties were assessed. SOL tablets showed the best results for tablet subdivision, particularly, the mean mass variation (3.9%) was significantly lower than the other two polymeric tablets (7.2% and 9.1% for PVPVA and HPMC, respectively), and showed better results than common tablets produced from powder matrices (7-14%). SOL tablets were also more sensitive to the different post-treatments applied, which reduced the mass loss and friability from 1.5% and 0.8%, respectively, to values close to zero and without altering their porosity. The thermal treatment of PVPVA tablets, in turn, also led to similar subdivision results, with mass loss of 0.3% and friability of 0.02%. In contrast, the granules of HPMC presented compaction difficulties making its tablets unsuitable for the subdivision process, even after additional post-treatment. Polymeric matrices with uniform internal structure and appropriate mechanical strength are the key to a better adaptation for the tablet subdivision.

Compounded gabapentin for neuropathic pain: Stability and beyond-use date (BUD) in some commonly used bases

OBJECTIVES

To investigate the stability and beyond-use date (BUD) of topical gabapentin in 3 commonly used bases.

METHODS

Lipoderm cream, Versabase gel, and Emollient cream were used to compound gabapentin (10%). The products were stored in Ecolojars, kept at 25°C, 4°C, and 40°C, and samples were collected on different days (days 0, 14, 28, and 90). Potency, stability, and organoleptic changes were monitored.

RESULTS

At 25°C and 40°C, the potency of gabapentin in Lipoderm cream significantly increased (P < 0.05) after 28 and 90 days, respectively. In contrast, gabapentin degraded in Emollient cream (P < 0.05). At 25°C, the organoleptic properties of the drug compounded with Lipoderm cream (25°C) remained consistent for up to 28 days but showed signs of physical changes in other bases. Gabapentin recrystallized from Versabase gel and Emollient cream within 14 days.

CONCLUSION

Gabapentin compounded with Lipoderm cream for topical use was stable in Ecolojars for 28 days at 25°C. Under the same conditions, the drug was not stable in Versabase gel and Emollient cream. Based on our stability and potency data, the beyond-use date of currently dispensed gabapentin (10%) formulations with Lipoderm cream should not be extended beyond the currently assigned 30-day mark, even when refrigerated. It is unclear whether the stability of these formulations is improved if stored in air-tight containers.

Investigating the Mechanism of L-Valine in Improving the Stability of Gabapentin Combining Chemical Analysis Experiments with Computational Pharmacy

The mechanism of L-Val on how to improve the stability of gabapentin (GBP) was described by the combination of chemical analysis experiments and computer simulations. Scanning electron microscope (SEM), powder X-ray diffraction (PXRD), and differential scanning calorimeter (DSC), coupled with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), were used to identify β-GBP prepared by rapid solvent removal method. The reaction barriers on crystal planes, β-GBP (100) and β-GBP (10-1), are smaller than α-GBP and γ-GBP, reaching 276.65 kJ/mol and 299.57 kJ/mol, respectively. Thus, it was easier for β-GBP to form lactam, and the occurrence of β-GBP would lead the worse stability of α-GBP. The addition of neutral amino acids such as L-Val could improve the stability of α-GBP effectively. The adsorption energy of α-GBP (002) crystal plane with L-Val is larger than that of other crystal planes, reaching 42.17 kJ/mol. Hydrogen bond was the combination of L-Val and GBP main crystal planes, which could inhibit the crystal transformation of α-GBP. These results suggest that neutral amino acid protectants, such as L-Val, could improve the stability of α-GBP effectively, and inhibition of crystal transformation is one of the effective methods to improve the stability of polymorphic drugs.

Tablet Splitting of Antiepileptic Drugs in Pediatric Epilepsy: Potential Effect on Plasma Drug Concentrations

INTRODUCTION

Tablet splitting is the process of dividing a tablet into portions to obtain a prescribed dose of medication. Very few studies have investigated whether split parts of a tablet deliver the expected amount of drug to patients.

OBJECTIVE

Our objectives were to evaluate the split parts of adult-dose tablet formulations for percentage of weight deviation, weight uniformity, weight loss, drug content, and the content uniformity of four antiepileptic drugs (AEDs) prescribed to pediatric patients. We also measured AED plasma concentrations in the children.

METHODS

We chose to study first-line AEDs (phenytoin sodium [PHE], sodium valproate [SVA], carbamazepine, and phenobarbitone) as they are routinely prescribed in India. We asked caregivers to perform the same splitting process they follow in their homes on three whole tablets during their routine visit to the outpatient department. After caregivers split the tablets, we studied the weight and content of the split parts. We also used high-performance liquid chromatography to study plasma drug concentrations in children who had received split AEDs for at least 4 months.

RESULTS

A total of 168 caregivers participated in the study, and we analyzed 1098 split tablet parts. In total, 539 (49.0 %) split parts were above the specified limit of the 2010 Indian Pharmacopeia (IP) acceptable percentage weight deviation (PHE 169 [48.8 %], SVA 187 [51.9 %], carbamazepine 56 [41.1 %], phenobarbitone 127 [49.6 %]); 456 (41.5 %) split parts were outside the proxy IP specification for drug content (PHE 135 [39.0 %], SVA 140 [38.8 %], carbamazepine 51 [37.5 %], phenobarbitone 130 [50.7 %]), and 253 split parts were outside the acceptable content uniformity range of <85 % and >115 % (PHE 85 [24.5 %], SVA 98 [27.2 %], carbamazepine 14 [10.2 %], phenobarbitone 56 [21.8 %]). In total, 130 (72.2 %) patients had plasma drug concentrations outside the therapeutic range (PHE 36 [72.0 %], SVA 39 [78.0 %], carbamazepine 34 [68.0 %], phenobarbitone 21 [70.0 %]).

CONCLUSIONS

Splitting adult-dosage formulations of AEDs results in patients not receiving the optimal dose. Plasma drug concentrations are also not optimal. Pediatric dosage formulations should be preferred to splitting adult-dosage formulations in pediatric epilepsy.

The stabilizing effect of moisture on the solid-state degradation of gabapentin

Gabapentin is known to undergo intramolecular cyclization to form a lactam (gaba-L) with concomitant loss of water. Gabapentin was milled in a planetary mill for 15-60 min. Unmilled and milled gabapentin were stored at 50°C with relative humidity ranged between 5% and 90%. The unmilled and milled samples were assayed for gabapentin and gaba-L by reversed phase-high-performance liquid chromatography and also subjected to powder X-ray diffraction, solid-state nuclear magnetic resonance and surface area analyses. The rates of lactamization in the milled gabapentin samples correlated to increased surface area, milling duration, and in-process lactam levels. This effect of milling could not be explained solely by the increase in surface area with increased milling time but was more likely due to increased regions of crystal disorder caused by the mechanical and thermal milling stresses. The lactamization rate of milled gabapentin samples was greatest in the presence of the lowest humidity conditions and dramatically decreased with increasing humidity. In particular, milled gabapentin appeared to be much more stable at humidity levels greater than 31% RH. This finding could not be attributed to the possibility of lactam hydrolysis at high humidity but rather to a competitive annealing process wherein milling-induced crystal defects were lost upon exposure to atmospheric moisture thereby stabilizing the milling-damaged drug substance.