Tablet splitting of narrow therapeutic index drugs: a nationwide survey in Taiwan

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 effectiveness of split tablet dosing versus alternate-day dosing of warfarin: a randomized control trial

Due to large dosage variation, a variety of warfarin prescription regimens are utilized for specific doses such as tablet splitting, or pill strength alternating. The clinical comparison between the two is lacking. We hypothesize that both approaches result in different times in therapeutic range. We randomized patients with specific warfarin dosage and stable INR for 6 months or longer to receive the whole tablet, alternate-day dosing or the split tablet, same daily-dosing regimen without initial dose change and followed them every 6 weeks for 6 months. The primary outcome was a time in therapeutic range of 2.0–3.0. The secondary outcomes included dosage, compliance, INR, anticoagulant-related events. A total of 66 patients were enrolled, 32 randomly assigned to the split tablet regimen (group S) and 34 to the alternate-day regimen (group A) with two withdrawers. The mean age was 58.6 ± 8.5 years. All baseline characteristics of both groups were similar. The average time in therapeutic range was 72.8 ± 25.4% in group S and 74.9 ± 22.0% in group A (p = 0.72). There were no significant differences in warfarin dosage, compliance, INR and, complications between the two groups. Both warfarin prescription methods, the split tablet and the alternate-day had comparable time in the therapeutic range.

Prescriber compliance to direct oral anticoagulant labels and impact on outcomes in Thailand

AIMS

This study aimed to evaluate the prescriber compliance to the approved labels of direct oral anticoagulants (DOACs) and impact of appropriateness of dosing on clinical outcomes.

METHODS

A retrospective study was conducted using simple-stratified random sampling of adult patients receiving ≥6 months of DOACs for various indications during 2013-2017 in 10 tertiary care hospitals. Patients were classified into 3 dosing groups including approved dose, underdosing and overdosing based on the Thai Food and Drug Administration-approved labels. Cox proportional hazard models were used to evaluate the impact of different dosings on thromboembolic and bleeding events.

RESULTS

From 1200 patients included in the data analysis, prescribing of DOACs was consistent with the approved indications in 1130 cases (94.2%) while 70 patients (5.8%) received DOACs despite having contraindications or with off-label usage. Among 1026 cases of dosing evaluation cohort, 688 patients (67.1%) received approved doses. There were 227 (21.9%) and 110 (10.7%) cases of underdosing and overdosing, respectively. Multivariate analysis showed that underdosing was associated with an increased risk of thromboembolism 3.023 (95% confidence interval [CI]: 1.291-7.080; P = .011) while overdosing was associated with an increased risk of bleeding requiring hospitalization (adjusted hazard ratio, 3.045; 95% CI, 1.501-6.178; P = .002) and Bleeding Academic Research Consortium type 2 or more (adjusted hazard ratio, 2.196; 95% CI, 1.083-4.452; P = .029).

CONCLUSION

Prescribers' compliance to approved indications were high. However, 1/3 of DOAC prescriptions were inconsistent with approved dosing. Dosing deviation was associated with an increase in adverse clinical outcomes.

Effect of different splitting techniques on the characteristics of divided tablets of five commonly split drug products in Jordan

Objective

To determine the accuracy, variability, and weight uniformity of tablet subdivision techniques utilized to divide the tablets of five drug products that are commonly prescribed for use as half tablets in Jordan.

Methods

Ten random tablets of five commonly subdivided drug products were weighed and subdivided using three subdivision techniques: hand breaking, kitchen knife, and tablet cutter. The five commonly subdivided drug products (warfarin 5 mg, levothyroxine 50 μg, levothyroxine 100 μg, candesartan 16 mg, and carvedilol 25 mg) were weighed. The weights were analyzed for acceptance, accuracy, and variability. Weight variation acceptance criteria were adopted in this work as a tool to indicate the properness of the subdivision techniques used to produce acceptable half tablets. Other relevant physical characteristics of the five products such as tablet shape, dimensions, face curvature, score depth, and crushing strength were measured.

Results

All tablets were round in shape, had weights that ranged between 100.63 mg (standard deviation=0.99) and 379.04 mg (standard deviation=3.00), and had crushing strengths that ranged between 23.29 N (standard deviation=3.58)and 103.35 N (standard deviation=14.98). Both candesartan and carvedilol were bi-convex in shape with an extent of face curvature equal to about 33%. In addition, percentage score depth of the tablets had a range between 0% and 24%. The accuracy and variability of subdivision varied according to the subdivision technique used and tablet characteristics. Accuracy range was between 81% and 109.8%. Moreover, the relative standard deviation was between 1.5% and 17.4%. Warfarin 5 mg subdivided tablets failed the weight variation test regardless of the subdivision technique used. Subdivision by hand produced half tablets that were acceptable for levothyroxine 50 μg and levothyroxine 100 μg. Subdivision by knife produced half tablets that were acceptable only for candesartan tablets. However, the tablet cutter produced half tablets that passed the weight variation test for four out of the five drug products tested in this study.

Conclusions

The tablet cutter performed better than the other subdivision techniques used. It produced half tablets that passed the weight uniformity test for four drug products out of the five.

Recent trends in tablet subdivision and factors affecting subdivision in South Korea: A cross-sectional study

Tablet subdivision by physicians or patients frequently occurs in various clinical settings for multiple reasons, including dose adjustment, alleviation of swallowing difficulties, or cost savings. However, not all tablets are suitable for subdivision, and it might cause side effects. It is informative to know which medicines are regularly subdivided, which healthcare institutions prescribe subdivided medicines, and to whom the medicines are prescribed from the perspectives of quality of care and patient safety. In this study, we aimed to examine recent trends in tablet subdivision and to address factors associated with subdivision of tablets both at the patient and healthcare institution levels.The yearly claims data in 2016 retrieved from the National Patients Sample provided by the Health Insurance Review and Assessment (HIRA-NPS). This study used descriptive statistics to examine characteristics of medicines that were frequently prescribed in subdivided forms, and retrieved information regarding the medicines to assess the appropriateness for tablet splitting. Then, we selected five medicines, and performed a multivariate logistic regression analysis to estimate the effect of the variables of interest on tablet subdivision.We presented the top 25 medicines prescribed in subdivided forms in 2016, and confirmed these medicines could be relevantly halved according to their Summary of Product Characteristics. Of the 25 medicines, 14 (56%), 5 (20%), and 3 (12%) medicines belonged to the respiratory system (R), nervous system (N), and systemic hormonal preparations (H), according to the first category of Anatomical Therapeutic Chemical (ATC) classification system, respectively. Being female at the patient level and tertiary healthcare institutions and private owned institutions at the institution level were positively associated with subdivision of medicines.Subdivision of tablets frequently occurred for vulnerable populations with various reasons. Female and geriatric patients are prescribed split medicines for clinical reasons, while low-income patients are prescribed nonsplit medicines for cost savings. It would be better if medicines were not so small, and if they had dividing lines on their surfaces to enable successful splitting of the tablet and to protect the health of vulnerable patients. Furthermore, avoid splitting those pharmacotherapies with a narrow therapeutic range, and provide a pharmacist assistance and a splitting device for unavoidable splitting.

Comparing Two Methods of Tablet Manipulation to Adjust the Warfarin Dose in Paediatric Care

Tablets containing prescribed doses are not always available, and this is of particular importance in paediatric care where suitable age-appropriate formulations are generally lacking. To obtain a child-adjusted dose, tablets are manipulated in several ways; e.g., they may be dispersed in water before a fraction is extracted, or they may be split before the resulting fragment is dispersed. In this study, the accuracy attained through these manipulation methods was investigated for two generic tablets containing the anticoagulant warfarin. Tablets were dispersed in water (10 mL) before a fraction (10%) was withdrawn, alternatively tablets were split in half or quarter fragments before the fragments were dispersed in water. To investigate the contribution of variability from the different steps in the manipulation processes, the amount of warfarin recovered from the various dispersions was determined, as was the accuracy of the splitting. A validated UHPLC-method was used for quantitative determination of warfarin. Splitting of the tablets could result in deviation >30% from the ideal, theoretical weight. The amount of drug substance extracted as a fraction from the dispersed tablets deviated no more than 10% from the intended amount. To obtain the most accurate child-adjusted fraction dose of warfarin, the tablets investigated in this study should be dispersed and the desired proportion extracted. Practices that involve splitting tablets are likely to increase the variation, and should be avoided.

Comparison of Treatment Response Achieved by Tablet Splitting Versus Whole Tablet Administration of Levothyroxine in Patients with Thyroid Cancer

Objectives

TSH suppression by Levothyroxine consumption is a mainstay of thyroid cancer treatment. Tablet-splitting is a worldwide approach in dose adjustment in patients. However, it is highly recommended to evaluate the validity of tablet splitting for each distinctive drug by clinical trials before routinely using tablet halves in clinical practice. In this study we compared the effect of 150 µg dose of Levothyroxine by use of a100 and a 50 µg tablets or one and half 100 µg tablets in Differentiated thyroid cancer (DTC) patients.

Methods

One hundred DTC patients treated with one and half 100 µg Levothyroxine tablets were randomly divided into two groups. The first group continued taking medication as before and the second group received the same daily dose by taking one 100 and one 50 microgram Levothyroxine tablets. The mean changes in TSH and T3 levels and patients weight were compared between the groups.

Results

91 patients completed the study. Levothyroxine consumption pattern, age, gender distribution, weight and TSH levels were comparable between groups at the beginning of the study. The mean change of body weights, serum levels of T3 and TSH showed no significant difference between groups in different time points during the study (P>0.05).

Conclusion

This study showed similar efficacy of tablet splitting and two tablets administration for Levothyroxine; however, patients preferred two tablets at the end of the study. It can be concluded that tablet splitting can be used as an alternative way when the 50 µg tablet is not available.

The influence of physical division of tablets on the variability of release kinetics of gliclazide

Abstract

Tablets are often used in splitting process when the appropriated, registered dose is not available on the market or patients exhibit swallowing difficulties caused by the size of the tablet. The aim of the work was to assess the impact of physical division of tablets on the kinetics of in vitro gliclazide release from the intact and divided tablets. Gliclazide was released from prolonged release tablets containing 30 or 60 mg of the drug into a phosphate buffer, pH 7.4 and the amount of the drug in acceptor fluid was determined by UV–Vis spectrophotometry. The dissolution profiles were fit to zero- and first-order kinetics as well as to the Korsmeyer-Peppas equation. The largest discrepancy in the values of rate constants was obtained in the case of the release of gliclazide from intact and from splitting tablets using zero- and first-order kinetics. The values of the rate constants k₀ obtained from the release of the drug from the intact tablets and from fragments with a dose of the drug of 30 mg were (4.2 ± 0.1) × 10⁻⁵ g min⁻¹ and (5.8 ± 0.1) × 10⁻⁵ g min⁻¹, respectively, and k₁ were (2.3 ± 0.1) × 10⁻³ min⁻¹ and (4.7 ± 0.6) × 10⁻³ min⁻¹, respectively. These discrepancies were confirmed by the value of f₂ coefficient that was 45.9. The results suggest that physical division of tablets accelerate the release of gliclazide from its prolonged form.

Graphical abstract

Comparative Effect of Divided Doses of Adult Solid and Liquid Oral Formulations of Antiepileptic Drugs in the Management of Pediatric Epilepsy

Objective:

To compare the differences in the efficacy and safety of the commonly prescribed AEDs in the management of epilepsy in children when using divided doses of adult solid oral formulations (DDSF) with the liquid oral formulations (LFs).

Materials and Methods:

Patients who had one or more seizures per month and prescribed with DDSF were recruited. Initially the patients were continued on DDSF for 4 months following which they were switched over to LF for the subsequent 4 months. Seizure frequencies and adverse drug effects (ADRs) were recorded every month for 8 months and plasma AED levels were estimated at the end of 4^th and 8^th months.

Results:

A total of 200 patients completed the study protocol. The median seizure frequencies per month with DDSF and LF were: partial seizures (20.5, 9.0; P < 0.001), generalized tonic-clonic seizures (6.5, 2.0; P < 0.001), myoclonic seizures (58.5, 29.0; P < 0.001). Mean plasma drug levels ± SD (μg/ml) with DDSF and LF were: sodium valproate (48.2 ± 13.7, 69.1 ± 16.3; P < 0.001), phenytoin sodium (5.0 ± 2.4, 12.8 ± 3.8; P < 0.001), carbamazepine (4.5 ± 2.0, 11.5 ± 4.8; P < 0.001) and phenobarbitone (14.1 ± 5.2, 25.4 ± 12.3, P < 0.001). The incidence of treatment emergent ADRs was poor scholastic performance (25.5%), behavioral problems and dizziness/sedation (21.0%), somnolence/sleep disorders (19.5%).

Conclusion:

Patients treated with LF had better seizure control and optimal therapeutic drug levels and less adverse effects when compared to DDSF.

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.

Evaluation of Certain Pharmaceutical Quality Attributes of Lisinopril Split Tablets

Tablet splitting is an accepted practice for the administration of drugs for a variety of reasons, including dose adjustment, ease of swallowing and cost savings. The purpose of this study was to evaluate the physical properties of lisinopril tablets as a result of splitting the tablets either by hand or with a splitting device. The impact of the splitting technique of lisinopril (Zestril^® tablets, 20 mg) on certain physical parameters such as weight variation, friability, disintegration, dissolution and drug content were studied. Splitting the tablets either by hand or with a splitter resulted in a minute but statistically significant average weight loss of <0.25% of the tablet to the surrounding environment. The variability in the weight of the hand-split tablet halves was more pronounced (37 out of 40 tablet halves varied by more than 10% from the mean weight) than when using the tablet splitter (3 out of 40 tablet halves). The dissolution and drug content of the hand-split tablets were therefore affected because of weight differences. However, the pharmacopoeia requirements for friability and disintegration time were met. Hand splitting of tablets can result in an inaccurate dose and may present clinical safety issues, especially for drugs with a narrow therapeutic window in which large fluctuations in drug concentrations are undesirable. It is recommended to use tablets with the exact desired dose, but if this is not an option, then a tablet splitter could be used.