Mini-tablets: a contemporary system for oral drug delivery in targeted patient groups

Reflection on the Pharmaceutical Formulation Challenges Associated with a Paediatric Investigation Plan for an Off-Patent Drug

In Europe, the development of pediatric medicines for new patent protected products is mandatory and applicants are required to submit a Paediatric Investigation Plan (PIP) to the regulatory authorities. The process is voluntary for off-patent medicines and despite the availability of incentives, there is still a huge unmet need for the development of off-patent pediatric medicines. The aim of the EU grant funded "Labeling of Enalapril from Neonates to Adolescents" (LENA) project is to develop a new pediatric dosage form of the off-patent drug enalapril, for the treatment of heart failure in patients aged from birth to 18 years. This article provides an overview of some of the key formulation challenges that were faced during the product development programme and PIP process, including selection of dosage form and excipients, methodology for administration of the product and evaluation of patient acceptability.

Formulating a poorly water soluble drug into an oral solution suitable for paediatric patients; lorazepam as a model drug

INTRODUCTION

Many drugs are unavailable in suitable oral paediatric dosage forms, and pharmacists often have to compound drugs to provide paediatric patients with an acceptable formulation in the right dose. Liquid formulations offer the advantage of dosing flexibility and ease of administration to young patients, but drug substances often show poor aqueous solubility. The objective of this work was to study different solvents and matrices to design a liquid formulation for poorly water soluble drugs, using lorazepam as model drug.

METHODS

Three different formulation strategies were explored to improve the solubility. Firstly, water-soluble organic solvents were used to improve the aqueous solubility directly, secondly, ionic surfactants were used to solubilise the model drug, and thirdly, complexation of lorazepam with cyclodextrin was studied. Specific attention was paid to excipients, adequate taste correction and palatability. For the final formulation, physical and chemical stability and microbiological quality were assessed for 12months.

RESULTS

An organic solvent based formulation, containing a mixture of polyethylene glycol and glycerol 85%, with a minimum amount of propylene glycol, proved to be physically and chemically stable. Development of the non-ionic surfactants formulation was discontinued due to taste problems. The cyclodextrin formulations were physically stable, but lorazepam content declined to 90% within five months. The final formulation contained in volume concentration (%v/v) 87% glycerol, 10% polyethylene glycol 400 and 3% propylene glycol. Orange essence was the preferred taste corrector. The formulation remained stable for 12months at 4°C, with lorazepam content remaining >95%. Related substances increased during the study period but remained below 2%. In-use stability was proven up to 4weeks.

CONCLUSION

An organic solvent based oral formulation was shown to be superior to a non-ionic surfactant based formulation or a cyclodextrin formulation. These results may help to formulate paediatric formulations of other poorly water soluble drugs, to aid pharmacy compounding.

Prolonged-release minitablets with carbamazepine – preliminary observations in vitro

Objective

The aim was to develop prolonged-release minitablets (MT) with carbamazepine (CBZ).

Methods

Matrix-type 3-mm MT (5 mg CBZ) were prepared by direct compression using hydrophilic (hypromellose) or hydrophobic polymers (ethylcellulose, Kollidon SR, glyceryl behenate). Coated prolonged-release MT (2.5 mm/3 mg of CBZ) were produced using ethylcellulose or Eudragit RL/RS. The release tests were performed in a basket apparatus with water or 1% sodium lauryl sulphate solution as dissolution media.

Key findings

High-viscosity hypromellose used as a matrix polymer resulted in slow release of CBZ (80% released during 12 h). Dissolution was slower from hydrophobic matrices. Non-swelling MT cores were successfully coated with Eudragit RL/RS, which resulted in the prolonged release of CBZ (80%/14 h), depending on the film thickness and Eudragit composition. Careful choice of pore formers in the coating film allowed to reduce lag time. Ethylcellulose was unsuitable as coating polymer due to low permeability to CBZ and unsatisfying mechanical resistance of the films modified with hypromellose.

Conclusion

Prolonged release of CBZ was obtained from both matrix-type and coated MT. Further development of MT as a single unit or multicompartment prolonged-release new dosage form especially suitable for children has been justified.

An optimised age-based dosing regimen for single low-dose primaquine for blocking malaria transmission in Cambodia

BACKGROUND

In 2012, the World Health Organization recommended the addition of single low-dose primaquine (SLDPQ, 0.25 mg base/kg body weight) to artemisinin combination therapies to block the transmission of Plasmodium falciparum without testing for glucose-6-phosphate dehydrogenase deficiency. The targeted group was non-pregnant patients aged ≥ 1 year (later changed to ≥ 6 months) with acute uncomplicated falciparum malaria, primarily in countries with artemisinin-resistant P. falciparum (ARPf). No dosing regimen was suggested, leaving malaria control programmes and clinicians in limbo. Therefore, we designed a user-friendly, age-based SLDPQ regimen for Cambodia, the country most affected by ARPf.

METHODS

By reviewing primaquine's pharmacology, we defined a therapeutic dose range of 0.15-0.38 mg base/kg (9-22.5 mg in a 60-kg adult) for a therapeutic index of 2.5. Primaquine doses (1-20 mg) were tested using a modelled, anthropometric database of 28,138 Cambodian individuals (22,772 healthy, 4119 with malaria and 1247 with other infections); age distributions were: 0.5-4 years (20.0 %, n = 5640), 5-12 years (9.1 %, n = 2559), 13-17 years (9.1 %, n = 2550), and ≥ 18 years (61.8 %, n = 17,389). Optimal age-dosing groups were selected according to calculated mg base/kg doses and proportions of individuals receiving a therapeutic dose.

RESULTS

Four age-dosing bands were defined: (1) 0.5-4 years, (2) 5-9 years, (3) 10-14 years, and (4) ≥15 years to receive 2.5, 5, 7.5, and 15 mg of primaquine base, resulting in therapeutic doses in 97.4 % (5494/5640), 90.5 % (1511/1669), 97.7 % (1473/1508), and 95.7 % (18,489/19,321) of individuals, respectively. Corresponding median (1st-99th centiles) mg base/kg doses of primaquine were (1) 0.23 (0.15-0.38), (2) 0.29 (0.18-0.45), (3) 0.27 (0.15-0.39), and (4) 0.29 (0.20-0.42).

CONCLUSIONS

This age-based SLDPQ regimen could contribute substantially to malaria elimination and requires urgent evaluation in Cambodia and other countries with similar anthropometric characteristics. It guides primaquine manufacturers on suitable tablet strengths and doses for paediatric-friendly formulations. Development of similar age-based dosing recommendations for Africa is needed.

Safe and effective pharmacotherapy in infants and preschool children: importance of formulation aspects

Safe and effective paediatric pharmacotherapy requires careful evaluation of the type of drug substance, the necessary dose and the age-appropriateness of the formulation. Generally, the younger the child, the more the attention that is required. For decades, there has been a general lack of (authorised) formulations that children are able to and willing to take. Moreover, little was known on the impact of pharmaceutical aspects on the age-appropriateness of a paediatric medicine. As a result of legislative incentives, such knowledge is increasingly becoming available. It has become evident that rapidly dissolving tablets with a diameter of 2 mm (mini-tablets) can be used in preterm neonates and non-rapidly dissolving 2 mm mini-tablets in infants from 6 months of age. In addition, uncoated 4 mm mini-tablets can be used in infants from the age of 1 year. Also, there is some evidence that children prefer mini-tablets over a powder, suspension or syrup. Other novel types of age-appropriate oral formulations such as orodispersible films may further add to the treatment possibilities. This review provides an overview of the current knowledge on oral formulations for infants and preschool children, the advantages and disadvantages of the different types of dosage forms and the age groups by which these can likely be used.

Comparison of metoprolol tartrate multiple-unit lipid matrix systems produced by different technologies

The aim of this study was to develop, evaluate and compare extended release mini-matrices based on metoprolol tartrate (MPT) and either glyceryl behenate (GB) or glyceryl palmitostearate (GPS). Mini-matrices were produced by three different techniques: hot melt extrusion, compression of melt granulates and prilling. Hot-melt extrusion and compression of granules obtained from melted material proved to be reliable, robust and reproducible techniques with aim of obtaining extended release matrices. Prilling tended to be susceptible to increased melt viscosity. Direct compression was not applicable for mini-matrix production due to poor powder flow. In general MPT release from all matrices was affected by its loading and the size of the units/particles. Processing of GB-MPT mixtures by different techniques did not lead to different drug release rates and patterns, while in case of GPS differently obtained matrices provided diverse MPT release outcomes. Matrices based on GB tended to have higher porosity compared to ones composed of GPS and thus most of the GB-based formulations showed faster drug delivery. FT-IR analysis revealed no interactions between primary components used for matrix production and Raman mapping outlined uniform MPT distribution throughout the units. DSC and X-ray studies revealed significant changes in the crystallinity of glycerides after storage under room conditions (GPS samples) and at increased temperature (GB and GPS samples), which was correlated to the changes seen in drug release rate and pattern after storage. Media composition in general tended to insignificantly affect GB matrices, while in case of GPS matrices increasing the pH and presence of biorelevant compounds induced faster drug release.

Formulation approaches to pediatric oral drug delivery: benefits and limitations of current platforms

Introduction: Most conventional drug delivery systems are not acceptable for pediatric patients as they differ in their developmental status and dosing requirements from other subsets of the population. Technology platforms are required to aid the development of age-appropriate medicines to maximize patient acceptability while maintaining safety, efficacy, accessibility and affordability.

Areas covered: The current approaches and novel developments in the field of age-appropriate drug delivery for pediatric patients are critically discussed including patient-centric formulations, administration devices and packaging systems.

Expert opinion: Despite the incentives provided by recent regulatory modifications and the efforts of formulation scientists, there is still a need for implementation of pharmaceutical technologies that enable the manufacture of licensed age-appropriate formulations. Harmonization of endeavors from regulators, industry and academia by sharing learning associated with data obtained from pediatric investigation plans, product development pathways and scientific projects would be the way forward to speed up bench-to-market age appropriate formulation development. A collaborative approach will benefit not only pediatrics, but other patient populations such as geriatrics would also benefit from an accelerated patient-centric approach to drug delivery.