Model-dependent pharmacokinetic analysis of enalapril administered to healthy adult volunteers using orodispersible minitablets for use in pediatrics

Orally disintegrating drug carriers for paediatric pharmacotherapy

Non-compliance, dosing inaccuracy, choking risk, flavour, and instability, are some of the issues associated with paediatric, oral dosage forms - tablets, capsules, solutions, and suspensions. Orally disintegrating drug carriers, a dosage form with growing interest, are thought to overcome several of the challenges associated with these conventional formulations by rapidly disintegrating within the buccal cavity without the need for water. This review serves as an up-to-date report on the various types of orodispersible delivery systems, currently being developed or commercialized, by detailing their characteristics, manufacturing processes, and applications in the paediatric population. Mentioned are orodispersible tablets, films, wafers and lyophilisates, mini-tablets, capsules, granules, electrospun fibers and webs. Also highlighted are the choice of excipients, quality control requirements, and expected pharmacokinetics of orally disintegrating drug carriers concerning the paediatric population. Overall, orodispersible formulations, particularly tablets, films, and lyophilisates/wafers, have shown to be a valuable addition to medication administration in minors, thus the execution of more targeted research and development activities is expected to lead to enhanced paediatric care and outcomes.

Enalapril and Enalaprilat Pharmacokinetics in Children with Heart Failure Due to Dilated Cardiomyopathy and Congestive Heart Failure after Administration of an Orodispersible Enalapril Minitablet (LENA-Studies)

Angiotensin-converting enzyme inhibitors (ACEI), such as enalapril, are a cornerstone of treatment for pediatric heart failure which is still used off-label. Using a novel age-appropriate formulation of enalapril orodispersible minitablets (ODMTs), phase II/III open-label, multicenter pharmacokinetic (PK) bridging studies were performed in pediatric patients with heart failure due to dilated cardiomyopathy (DCM) and congenital heart disease (CHD) in five participating European countries. Children were treated for 8 weeks with ODMTs according to an age-appropriate dosing schedule. The primary objective was to describe PK parameters (area under the curve (AUC), maximal concentration (Cmax), time to reach maximal concentration (t-max)) of enalapril and its active metabolite enalaprilat. Of 102 patients, 89 patients (n = 26, DCM; n = 63 CHD) were included in the primary PK endpoint analysis. Rate and extent of enalapril and its active metabolite enalaprilat were described and etiology and age could be identified as potential PK modifying factors. The dosing schedule appeared to be tolerated well and did not result in any significant drug-related serious adverse events. The PK analysis and the lack of severe safety events supports the applied age-appropriate dosing schedule for the enalapril ODMTs.

Transfer and scale-up of the manufacturing of orodispersible mini-tablets from a compaction simulator to an industrial rotary tablet press

Orodispersible mini-tablets (ODMTs) are a promising dosage form for the pediatric use showing increasing interest from pharmaceutical industry. However, a scale-up process for ODMTs from a compaction simulator to a rotary tablet press following FDA and EMA guidelines has not been performed and investigated yet. Isomalt (galenIQ™721) and Ludiflash® both excipients with proven suitability for the development of ODMTs have been investigated in transfer and scale-up from a compaction simulator to a rotary tablet press. ODMTs with isomalt and Ludiflash® were produced on the rotary tablet press monitoring the product temperature over time and assessing the properties of the residual powder in the feed shoe. Critical quality attributes like tensile strength, mass and disintegration time were evaluated. The transfer from compaction simulator to rotary tablet press succeeded as for both excipients similar disintegration times, tabletability and compactibility profiles were obtained. However, during scale-up, disintegration time significantly increases over time for both excipients. Monitoring of the product temperature revealed that with increasing batch size the product temperature increases as well having a significant impact on disintegration time. The properties of ODMTs produced with the residual powder are comparable in tabletability and disintegration time compared with ODMTs produced from fresh powder.

Effect of CES1 genetic variation on enalapril steady-state pharmacokinetics and pharmacodynamics in healthy subjects

AIMS

Enalapril is a prodrug and needs to be activated by carboxylesterase 1 (CES1). A previous in vitro study demonstrated the CES1 genetic variant, G143E (rs71647871), significantly impaired enalapril activation. Two previous clinical studies examined the impact of G143E on single-dose enalapril PK (10 mg); however, the results were inconclusive. A prospective, multi-dose, pharmacokinetics and pharmacodynamics (PK/PD) study was conducted to determine the impact of the CES1 G143E variant on enalapril steady-state PK and PD in healthy volunteers.

METHODS

Study participants were stratified to G143E non-carriers (n = 15) and G143E carriers (n = 6). All the carriers were G143E heterozygotes. Study subjects received enalapril 10 mg daily for seven consecutive days prior to a 72 hour PK/PD study. Plasma concentrations of enalapril and its active metabolite enalaprilat were quantified by an established liquid chromatography-tandem mass spectrometry (LC-MS/MS) method.

RESULTS

The CES1 G143E carriers had 30.9% lower enalaprilat C_max (P =  0.03) compared to the non-carriers (38.01 vs. 55.01 ng/mL). The carrier group had 27.5% lower AUC_0-∞ (P =  0.02) of plasma enalaprilat compared to the non-carriers (374.29 vs. 515.91 ng*h/mL). The carriers also had a 32.3% lower enalaprilat-to-enalapril AUC_0-∞ ratio (P =  0.003) relative to the non-carriers. The average maximum reduction of systolic blood pressure in the non-carrier group was approximately 12.4% at the end of the study compared to the baseline (P =  0.001). No statistically significant blood pressure reduction was observed in the G143E carriers.

CONCLUSIONS

The CES1 loss-of-function G143E variant significantly impaired enalapril activation and its systolic blood pressure-lowering effect in healthy volunteers.

Pharmacology of enalapril in children: a review

Enalapril is an angiotensin-converting enzyme (ACE) inhibitor that is used for the treatment of (paediatric) hypertension, heart failure and chronic kidney diseases. Because its disposition, efficacy and safety differs across the paediatric continuum, data from adults cannot be automatically extrapolated to children. This review highlights paediatric enalapril pharmacokinetic data and demonstrates that these are inadequate to support with certainty an age-related effect on enalapril/enalaprilat pharmacokinetics. In addition, our review shows that evidence to support effective and safe prescribing of enalapril in children is limited, especially in young children and heart failure patients; studies in these groups are either absent or show conflicting results. We provide explanations for observed differences between age groups and indications, and describe areas for future research.

Orodispersible minitablets of enalapril for use in children with heart failure (LENA): Rationale and protocol for a multicentre pharmacokinetic bridging study and follow-up safety study

Introduction

Treatment of paediatric heart failure is based on paradigms extensively tested in the adult population assuming similar underlying pathophysiological mechanisms. Angiotensin converting enzyme inhibitors (ACEI) like enalapril are one of the cornerstones of treatment and commonly used off-label in children. Dose recommendations have been extrapolated from adult experience, but the relationship between dose and pharmacokinetics (PK) in (young) children is insufficiently studied. Furthermore, appropriate paediatric formulations are lacking. Within the European collaborative project LENA, a novel formulation of enalapril orodispersible minitablets (ODMT), suitable for paediatric administration, will be tested in (young) children with heart failure due to either dilated cardiomyopathy or congenital heart disease in two pharmacokinetic bridging studies. Paediatric PK data of enalapril and its active metabolite enalaprilat will be obtained. In a follow-up study, the safety of enalapril ODMTs will be demonstrated in patients on long-term treatment of up to 10 months. Furthermore, additional information about pharmacodynamics (PD) and ODMT acceptability will be collected in all three studies.

Methods and Analysis

Phase II/III, open-label, multicentre study. Children with dilated cardiomyopathy (DCM) (n = 25; 1 month to less than 12 years) or congenital heart disease (CHD) (n = 60; 0 to less than 6 years) requiring or already on ACEI will be included. Exclusion criteria include severe heart failure precluding ACEI use, hypotension, renal impairment, hypersensitivity to ACEI. For those naïve to ACEI up-titration to an optimal dose will be performed, those already on ACEI will be switched to an expected equivalent dose of enalapril ODMT and optimised. In the first 8 weeks of treatment, a PK profile will be obtained at the first dose (ACEI naïve patients) or when an optimal dose is reached. Furthermore, population PK will be done with concentrations detected over the whole treatment period. PD and safety data will be obtained at least at 2-weeks intervals. Subsequently, an intended number of 85 patients will be followed-up up to 10 months to demonstrate long-term safety, based on the occurrence of (severe) adverse events and monitoring of vital signs and renal function.

Ethics and dissemination

Clinical Trial Authorisation and a favourable ethics committee opinion were obtained in all five participating countries. Results of the studies will be submitted for publication in a peer-reviewed journal.

Trial registration numbers

EudraCT 2015-002335-17, EudraCT 2015-002396-18, EudraCT 2015-002397-21.

Simultaneous Semi-Mechanistic Population Pharmacokinetic Modeling Analysis of Enalapril and Enalaprilat Serum and Urine Concentrations From Child Appropriate Orodispersible Minitablets

Enalapril is recommended as the first line of therapy and is proven to improve survival rates for treatment of Pediatric Heart Failure; however, an approved drug and child appropriate dosage formulation is still absent. The present analysis was conducted to perform a detailed model informed population pharmacokinetic analysis of prodrug enalapril and its active metabolite enalaprilat in serum and urine. Further, a model informed dosage form population-pharmacokinetic analysis was conducted to evaluate differences in pharmacokinetics of enalapril and its active metabolite enalaprilat when prodrug was administered to 24 healthy adults in a crossover, two periods, two treatments, phase I clinical trial using child-appropriate orodispersible mini-tablets (ODMT) and reference (Renitec®) dosage formulation. A simultaneous semi-mechanistic population-pharmacokinetic model was developed using NONMEM software, which predicted full profile serum and urine concentrations of enalapril and enalaprilat. First-order conditional estimation with interaction was used for parameter estimation. Transit compartments added using Erlang distribution method to predicted enalapril absorption and enalaprilat formation phases. Normalized body weight was identified as covariate related to enalapril volume of distribution. Visual predictive check (VPC) plots and conducted bootstrap analysis validated the model. The data from the two formulations were pooled for population-pharmacokinetic analysis and covariate effect of the formulation was found on mean transit time (MTT1) of enalapril absorption. In addition, data of each formulation were modeled separately and the estimated parameters of each individual administered both formulations were correlated using paired samples Wilcoxon rank test (p < 0.05 = significant) which also showed only a significant difference (p = 0.03) in MTT1 i.e., 5 min early appearance of enalapril from ODMT compared to reference tablets. No difference in the pharmacokinetics of active enalaprilat was found from the ODMT compared to the reference formulation. The population pharmacokinetic analysis provided detailed information about the pharmacokinetics of enalapril and enalaprilat, which showed that the ODMT formulation might have similar pharmacodynamic response compared to the reference formulation.