Retrospective analysis of the biopharmaceutics characteristics of solid oral Modified-Release drug products in approved US FDA NDAs designated as Extended-Release or Delayed-Release formulations

BACKGROUND

Modified Release (MR) orally administered drugs products [Extended-Release (ER) and Delayed-Release (DR)] differ from Immediate-Release (IR) drug products in their drug release site and/or rate to offer therapeutic advantages. It is important to understand the biopharmaceutics factors that determine how a drug works in the gastrointestinal tract and the various pharmacokinetic properties that determine a drug's rate of absorption and release in the human body. To better understand the biopharmaceutics characteristics of ER and DR drug products, this study retrospectively analyzed submissions approved by the US Food and Drug Administration (FDA), from 2001 to 2021, and their corresponding review documents. This review work is expected to enhance the readers' understanding regarding the biopharmaceutics properties that supported approval of these products' ER claims, as per 21 CFR 320.25(f), and DR claims.

METHODS

A comprehensive search was conducted using the FDA's internal New Drug Application (NDA) database for ER and DR oral drug products approved between 2001 and 2021. The search yielded 87 ER applications (23 ER capsules and 64 ER tablets) and 21 DR applications (10 DR capsules, 11 DR tablets) for which electronic records were accessible. These products were analyzed for overall drug product design, dosing frequency compared to the reference (if applicable), degree of fluctuation, dissolution method, and alcohol dose-dumping.

RESULTS

Out of 87 total applications for ER drug products that were assessed, 62% of the ER tablets contained a polymer matrix formulation, and hypromellose (HPMC) was used in 50% of these products. 52% of the ER capsules consisted of polymer beads while about half of the DR drug products contained a non-bead formulation with a combination of polymers. The majority of ER drug products were found to have a reduction in dosing frequency and a decrease in the degree of fluctuation when compared to the IR reference product. The 13 ER drug products that exhibited an increase in degree of fluctuation exhibited general and pharmacodynamic benefits, such as reduced dosing frequency and reduced pill burden. The majority of DR formulations were developed to prevent drug degradation in the stomach, followed by to decrease potential stomach irritation, and lastly for localized release in the colon. The majority of ER drug products had 1:1 ratios of dissolution duration compared to dosing frequency (i.e., the majority of ER drug products had a dissolution duration of 24 h and were dosed every 24 h while those with a dissolution duration of 12 h were dosed every 12 h). The majority of ER applications had single-stage dissolution methods while most DR drug products used biphasic dissolution methods. All of the DR dissolution methods incorporated an acid stage of 2 h and a buffer stage with various timeframes. 53% the DR drug products had a ratio of dissolution duration to dosing frequency of 1:4 (e.g. a dissolution duration of 2 h to a dosing frequency of 8 h) or 1:8 (e.g. a dissolution duration of 2 h to a dosing frequency of 16 h). Of the ER tablets and DR drug products, 72% exhibited no alcohol dose-dumping under in vitro testing conditions. ER capsules, however, did not yield similar results-most of which exhibited alcohol induced dose-dumping. Alcohol dose dumping was mitigated by either in vivo studies or warnings on the drug product label.

CONCLUSION

The results of this study help the reader understand the design, characteristics, and pharmacological advantages of the ER and DR drug products for patient benefit; as well as the regulations governing the FDA's assessment of ER claims.

Novel treatments for congenital adrenal hyperplasia

Patients with classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21OHD) need life-long medical treatment to replace the lacking glucocorticoids and potentially lacking mineralocorticoids and to lower elevated adrenal androgens. Long-term complications are common, including gonadal dysfunction, infertility, and cardiovascular and metabolic co-morbidity with reduced quality of life. These complications can be attributed to the exposure of supraphysiological dosages of glucocorticoids and the longstanding exposure to elevated adrenal androgens. Development of novel therapies is necessary to address the chronic glucocorticoid overexposure, lack of circadian rhythm in glucocorticoid replacement, and inefficient glucocorticoid delivery with concomitant periods of hyperandrogenism. In this review we aim to give an overview about the current treatment regimens and its limitations and describe novel therapies especially evaluated for 21OHD patients.

Development and verification of an endogenous PBPK model to inform hydrocortisone replacement dosing in children and adults with cortisol deficiency

The goal of hormone replacement is to mirror physiology. Hydrocortisone granules and modified release formulations are being developed to optimise cortisol replacement in the rare disease of adrenal insufficiency. To facilitate clinical development, we built and verified a physiologically based pharmacokinetic (PBPK) model for the endogenous hormone cortisol (hydrocortisone) in healthy adults, and children and adults with adrenal insufficiency. The model predicted immediate-release hydrocortisone pharmacokinetics in adults across the dose range 0.5 to 20 mg, with predicted/observed AUCs within 0.8 to 1.25-fold.  The model also tightly predicted pharmacokinetic parameters for modified-release formulations, with AUCs within 0.8 to 1.25-fold after single and multiple dosing.  Predicted modified-release formulation pharmacokinetics (PK) in 12 to 18-year olds showed PK to be similar to adults. This hydrocortisone PBPK model is a useful tool to predict adult and paediatric pharmacokinetics of both immediate- and modified-release hydrocortisone formulations, and develop clinical dosing regimens.

Polymeric-based drug delivery systems for veterinary use: State of the art

One of the challenges to the success of veterinary pharmacotherapy is the limited number of drugs and dosage forms available exclusively to this market, due to the interspecies variability of animals, such as anatomy, physiology, pharmacokinetics, and pharmacodynamics. For this reason, studies in this area have become a highlight, since they are still scarce in comparison with those on human drug use. To overcome many limitations related to the bioavailability, efficacy, and safety of pharmacotherapy in animals, especially livestock and domestic animals, polymers-based drug delivery systems are promising tools if they guarantee greater selectivity and less toxicity in dosage forms. In addition, these tools may be developed according to the great interspecies variability. To contribute to these discussions, this paper provides an updated review of the major polymer-based drug delivery systems projected for veterinary use. Traditional and innovative drug delivery systems based on polymers are presented, with an emphasis on films, microparticles, micelles, nanogels, nanoparticles, tablets, implants and hydrogel-based drug delivery systems. We discuss important concepts for the veterinarian about the mechanisms of drug release and, for the pharmacist, the advantages in the development of pharmaceutical forms for the animal population. Finally, challenges and opportunities are presented in the field of pharmaceutical dosage forms for veterinary use in response to the interests of the pharmaceutical industry.

Preformulation-Assisted Design and Characterization of Modified Release Gastroretentive Floating Extrudates Towards Improved Bioavailability and Minimized Side Effects of Baclofen

Baclofen immediate release mode of administration exhibit sharp plasma peaking that results in the emergence of side effects like hypotension. This research employs preformulation studies to design an optimum dosage form for baclofen to enhance therapeutic outcomes. These studies include partition coefficient and ex-vivo permeation studies. Partition coefficient was found to be 1.27 at pH 7.4. Permeation studies confirmed the presence of specialized transport mechanism through the GIT. It was concluded that an ideal formulation of baclofen should provide slow-release of the drug to avoid sharp peaking. Modified-release floating extrudates of baclofen were prepared using Carbopol 934 and HPMC with different gas-forming agents. Different release-retarding materials (Eudragit L100, Eudragit RS100 and Cetyl alcohol) were used as ingredients in the binder solutions. The prepared extrudates were assessed for their drug content, floating ability, friability properties and in vitro release properties. The prepared extrudates recorded buoyance characteristics for 24 h with a floating lag time varying from 0 to 73.34 s. The optimized extrudates manifested extended baclofen release for up to 8 h compared to 0.2 h for marketed baclofen tablets. This approach was found efficient to provide greater bioavailability and minimize hypotension associated with commercial baclofen tablets.

Development and validation of a Level A in-vitro in-vivo correlation for tofacitinib modified-release tablets using extrudable core system osmotic delivery technology

PURPOSE

To determine if a validated Level A in-vitro in-vivo correlation (IVIVC) could be achieved with the extrudable core system (ECS) osmotic tablet platform. Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis.

METHODS

Fast-, medium-, and slow-release modified-release formulations of 11 mg tofacitinib ECS tablets, and one formulation of 22 mg tofacitinib ECS tablet, were manufactured. In vitro dissolution of the tofacitinib ECS tablets was performed using USP Apparatus 2 (paddles) and in vivo pharmacokinetic (PK) data were obtained from a Phase 1 study in healthy volunteers. A 5 mg immediate-release formulation tablet was included to support deconvolution of the tofacitinib ECS PK tablet data to obtain the in vivo absorption profiles. A linear, piecewise correlation and a simple linear correlation were used to build and validate two IVIVC models.

RESULTS

The prediction errors (PEs) for the linear, piecewise correlation met the Food and Drug Administration's criteria for establishing a Level A IVIVC, with a maximum absolute individual internal PE of 4.6%, a maximum absolute average internal PE of 3.9%, and a maximum absolute external PE of 8.4% obtained.

CONCLUSIONS

This study demonstrates that the tofacitinib ECS osmotic tablet platform can achieve a Level A IVIVC, similar to other osmotic delivery systems.

Using zeta potential to study the ionisation behaviour of polymers employed in modified-release dosage forms and estimating their pKa

A range of enteric polymers is used in pharmaceutical industry for developing gastro-resistant formulations. It is generally implied that these coatings are interchangeable due to similar dissolution pH thresholds reported by suppliers. Despite rapid dissolution in compendial phosphate buffers, these products can take up to 2 h to disintegrate in-vivo in the human small intestine. The factors primarily responsible for such variability in dissolution of these polymeric coatings are the differences in ionisation of acidic functional groups on polymer chains and their interplay with ions and buffer species present in gastrointestinal fluids. In this study, we aim to develop a novel, simple and inexpensive technique that can be used under various in-vitro conditions to study the ionisation behaviour of commonly used polymers (EUDRAGIT-E100, L100, S100, HPMC AS-LF, AS-HF, HP-50, HP-55) and to estimate their pK_a. Moreover, this method was successfully applied to study the ionisation behaviour of a range of natural polymers (Guar, Tara, locust bean, Konjac gums, gum Arabic, citrus pectin, chitosan and alginate) and their pK_a was also estimated. The proposed method would allow a better understanding of the dissolution behaviour of these polymers within gastrointestinal tract and will aid rational design of modified release dosage forms.

Modified-release oral calcifediol corrects vitamin D insufficiency with minimal CYP24A1 upregulation

Vitamin D insufficiency is prevalent in chronic kidney disease (CKD) and associated with secondary hyperparathyroidism (SHPT) and increased risk of bone and vascular disease. Unfortunately, supplementation of stage 3 or 4 CKD patients with currently recommended vitamin D2 or D3 regimens does not reliably restore serum total 25-hydroxyvitamin D to adequacy (≥30ng/mL) or effectively control SHPT. Preclinical and clinical studies were conducted to evaluate whether the effectiveness of vitamin D repletion depends, at least in part, on the rate of repletion. A modified-release (MR) oral formulation of calcifediol (25-hydroxyvitamin D3) was developed which raised serum 25-hydroxyvitamin D3 and calcitriol levels gradually. Single doses of either bolus intravenous (IV) or oral MR calcifediol were administered to vitamin D deficient rats. Bolus IV calcifediol produced rapid increases in serum 25-hydroxyvitamin D3, calcitriol and FGF23, along with significant induction of CYP24A1 in both kidney and parathyroid gland. In contrast, oral MR calcifediol produced gradual increases in serum 25-hydroxyvitamin D3 and calcitriol and achieved similar hormonal exposure, yet neither CYP24A1 nor FGF23 were induced. A 10-fold greater exposure to bolus IV than oral MR calcifediol was required to similarly lower intact parathyroid hormone (iPTH). Single doses of oral MR (450 or 900μg) or bolus IV (450μg) calcifediol were administered to patients with stage 3 or 4 CKD, SHPT and vitamin D insufficiency. Changes in serum 25-hydroxyvitamin D3 and calcitriol and in plasma iPTH were determined at multiple time-points over the following 42 days. IV calcifediol produced abrupt and pronounced increases in serum 25-hydroxyvitamin D3 and calcitriol, but little change in plasma iPTH. As in animals, these surges triggered increased vitamin D catabolism, as evidenced by elevated production of 24,25-dihydroxyvitamin D3. In contrast, MR calcifediol raised serum 25-hydroxyvitamin D3 and calcitriol gradually, and meaningfully lowered plasma iPTH levels. Taken together, these studies indicate that rapid increases in 25-hydroxyvitamin D3 trigger CYP24A1 and FGF23 induction, limiting effective exposure to calcitriol and iPTH reduction in SHPT. They also support further investigation of gradual vitamin D repletion for improved clinical effectiveness. This article is part of a Special Issue entitled "17th Vitamin D Workshop".