Best practices for the development, scale-up, and post-approval change control of IR and MR dosage forms in the current quality-by-design paradigm

In this whitepaper, the Manufacturing Technical Committee of the Product Quality Research Institute provides information on the common, best practices in use today in the development of high-quality chemistry, manufacturing and controls documentation. Important topics reviewed include International Conference on Harmonization, in vitro-in vivo correlation considerations, quality-by-design approaches, process analytical technologies and current scale-up, and process control and validation practices. It is the hope and intent that this whitepaper will engender expanded dialog on this important subject by the pharmaceutical industry and its regulatory bodies.

In vitro and in vivo characterization of amorphous, nanocrystalline, and crystalline ziprasidone formulations

Ziprasidone, commercially available as Geodon capsules, is an atypical antipsychotic used in the treatment of schizophrenia and bipolar disorder. It is a BCS Class II drug that shows up to a 2-fold increase in absorption in the presence of food. Because compliance is a major issue in this patient population, we developed and characterized solubilized formulations of ziprasidone in an effort to improve absorption in the fasted state, thereby resulting in a reduced food effect. Three formulations utilizing solubilization technologies were studied: (1) an amorphous inclusion complex of ziprasidone mesylate and a cyclodextrin, (2) a nanosuspension of crystalline ziprasidone free base, and (3) jet-milled ziprasidone HCl coated crystals made by spray drying (CCSD) the drug with hypromellose acetate succinate. The formulations were characterized by in vitro methods appropriate to each particular solubilization technology. These studies confirmed that ziprasidone mesylate - cyclodextrin was an amorphous inclusion complex with enhanced dissolution rates. The ziprasidone free base crystalline nanosuspension showed a mean particle size of 274 nm and a monomodal particle size distribution. In a membrane permeation test, the CCSD showed a 1.5-fold higher initial flux compared to crystalline ziprasidone HCl. The three formulations were administered to fasted beagle dogs and their pharmacokinetics compared to Geodon capsules administered in the fed state. The amorphous complex and the nanosuspension showed increased absorption in the fasted state, indicating that solubilized formulations of ziprasidone have the potential to reduce the food effect in humans.

Challenges and opportunities in establishing scientific and regulatory standards for assuring therapeutic equivalence of modified release products: workshop summary report

Modified release products are complex dosage forms designed to release drug in a controlled manner to achieve desired efficacy and safety. Inappropriate control of drug release from such products may result in reduced efficacy or increased toxicity. This workshop provided an opportunity for pharmaceutical scientists from academia, industry, and regulatory agencies to discuss current industry practices and regulatory expectations for demonstrating pharmaceutical equivalence and bioequivalence of MR products, further facilitating the establishment of regulatory standards for ensuring therapeutic equivalence of these products.

Formulation design and pharmaceutical development of a novel controlled release form of azithromycin for single-dose therapy

BACKGROUND

Azithromycin's long serum half-life (approximately 68 hours) allows for a short 5-day, 3-day, and now 1-day course therapy with a large 2-g dose. Although the single-dose, 1-day therapy offers the advantage of 100% patient compliance, tolerance of such large dose becomes an issue.

METHODS

The dosage form discussed in this article employed a melt-congealing process to produce matrix microspheres with a 3-hour, first-order release. The vehicle blend included alkalizing agents to minimize GI side effects, minimize loss of bioavailability, and mask the bitter taste of azithromycin.

RESULTS

Azithromycin microspheres are small (approximately 200 microm) with a narrow particle size distribution. Drug release was optimized by controlling the amount of dissolution enhancer in the microspheres and by the addition of proper amount of alkalizing agents in the vehicle blend. The final formulation was selected based on a balance between bioavailability and tolerability.

CONCLUSIONS

Drug release from the microspheres was shown to occur via diffusion through the larger pores formed by dissolution of azithromycin crystals and the smaller interconnected pores formed by dissolution of poloxamer. Several clinical studies have been conducted with the formulation to evaluate its pharmacokinetics and to demonstrate its safety and efficacy. The combined suspension formulation for a 2-g dose of azithromycin provided taste-masking and good tolerability.

Assessment of the feasibility of oral controlled release in an exploratory development setting

Controlled release (CR) formulations have generally been considered as follow-ons to conventional immediate release formulations to manage the life cycle of a product. Although significant opportunities exist to use CR as an enabling technology for certain exploratory drug candidates, they have not been fully exploited. However, progress made in assessing CR feasibility based on the physicochemical and biopharmaceutical properties of the drug, together with advances made in understanding the various CR technologies and developing formulations in a fast and efficient manner, have increasingly made it possible to consider CR in an exploratory development setting.

Oral delivery of medications to companion animals: palatability considerations

There is an increased need for highly palatable solid oral dosage forms for companion animals, which are voluntarily accepted by the dog or cat, either from a feeding bowl or from the outstretched hand of the pet owner. Such dosage forms represent an emerging trend in companion animal formulations with major impact on medical needs such as convenience and compliance, particularly for chronically administered medications, and on marketing needs such as product differentiation. This review focuses on the science of taste, food and flavor preferences of dogs and cats, and palatability testing, in the context of applying these principles to the development of an oral palatable tablet for companion animals.

Osmotic drug delivery using swellable-core technology

Swellable-core technology (SCT) formulations that used osmotic pressure and polymer swelling to deliver drugs to the GI tract in a reliable and reproducible manner were studied. The SCT formulations consisted of a core tablet containing the drug and a water-swellable component, and one or more delivery ports. The in vitro and in vivo performance of two model drugs, tenidap and sildenafil, formulated in four different SCT core configurations: homogeneous-core (single layer), tablet-in-tablet (TNT), bilayer, and trilayer core, were evaluated. In vitro dissolution studies showed that the drug-release rate was relatively independent of the core configuration but the extent of release was somewhat lower for the homogeneous-core formulation, particularly under non-sink conditions. The drug-release rate was slower with increasing coating thickness and decreasing coating permeability, and was relatively independent of the drug loading and the number and size of the delivery ports. The drug-release rates were similar for the two model drugs despite significant differences in their physicochemical properties. Tablet-recovery and pharmacokinetic studies conducted in beagle dogs showed that the in vivo release of drug from SCT formulations was comparable to the in vitro drug release.

Delivery of glipizide from asymmetric membrane capsules using encapsulated excipients

The aim of this study was to demonstrate that the asymmetric membrane capsule can be used to deliver a poorly water soluble drug with a pH sensitive solubility such as glipizide. In order to obtain the desired delivery duration, the drug was solubilized with the use of a pH-controlling excipient. In osmotic systems, the release rate of an excipient relative to the release rate of the drug is an important factor that determines the duration of drug release. Thus, highly water-soluble excipients are released much faster than the drug, which can limit their usefulness. In the case of the asymmetric membrane capsule, it was shown that this limitation could be overcome by encapsulating the pH-controlling excipient in a membrane and including the coated excipient in the asymmetric membrane capsule core to prolong its availability within the core. Thus, prolonged release of glipizide could be obtained with the asymmetric membrane capsule.

Asymmetric membrane capsules for osmotic drug delivery. I. Development of a manufacturing process

This paper describes a novel non-disintegrating polymeric capsule and a manual and a semi-automatic process developed for its manufacture. The capsule wall was made by a phase inversion process in which the membrane structure was precipitated on stainless steel mold pins by dipping the mold pins into a coating solution containing a polymer-solvent-nonsolvent system followed by dipping into a quench solution. The resulting asymmetric membrane wall was composed of a thin dense region supported on a thicker porous region. The asymmetric membrane capsules can be filled with a blend of the active agent and excipients for use in osmotically modulated controlled drug delivery applications.

Asymmetric membrane capsules for osmotic drug delivery II. In vitro and in vivo drug release performance

In a previous paper, we described asymmetric membrane capsules and a phase inversion process for manufacturing them. In this paper, we describe the in vitro and in vivo drug release characteristics from these capsules. The capsule formulations were developed with model drugs to understand the variables that influenced drug release. Studies were also conducted to understand the drug release mechanism and it was shown that osmotic drug delivery was possible with asymmetric membrane capsules.

The kinetics of timolol in the rabbit lens: implications for ocular drug delivery

This study examines the uptake and distribution of timolol in the rabbit lens following topical instillation using a heuristic approach. The implications of anisotropic drug diffusion through the lens are presented here and discussed in the context of actual in vivo data. The dynamics of timolol in the lens involve an initial, rapid uptake of the drug by the capsule and epithelium followed by slower, anisotropic diffusion through the cortex body. Kinetically, the capsule and epithelium can be treated as a separate compartment which is distinct from the cortex and which serves to provide a concentration gradient for subsequent diffusion of timolol into the dense interior structures of the lens. Model simulations support the hypothesis that the preferred route of penetration of timolol into the vitreous humor via the lens is the diffusion of drug around the capsule/epithelium and peripheral cortical layers. It is also shown that due to the high and increasing diffusional resistance toward the center of the lens, as well as the diminishing drug concentrations in the capsule and epithelium, steady-state levels in the lens may be extremely difficult to achieve in some therapeutic situations. This phenomenon could have a significant impact on the success or failure of a drug treatment involving the lens and ocular tissues.

Modelling of drug release kinetics from a laminated device having an erodible drug reservoir

The purpose of this communication is to present a preliminary analysis to demonstrate the effect of laminating a drug-containing erodible polymer matrix with a second barrier membrane. A mathematical model for the diffusive release of the drug from an erodible polymer device undergoing surface erosion has been extended to similar devices with a secondary membrane to allow a comparison of the results. The results indicate that the constant rate of release characteristic of erodible devices is not sacrificed with the addition of the secondary membrane; moreover, the membrane provides additional controllable parameters at the disposal of the device designer.

Quantitative evaluation of topically applied pilocarpine in the precorneal area

The bioavailability of topically applied pilocarpine is poor due to various loss mechanisms that serve to lessen delivery of the drug to the aqueous humor. Precorneal drainage and other routes of loss have been investigated qualitatively as well as quantitatively. The mechanistic models proposed to date suffer from the drawback of being dependent on our understanding of the mechanism of drug transport through the corneal membrane. This report quantifies the initial disposition of topically applied drugs and their availability for systemic and local absorption. The rate constant for the conjunctival absorption is determined and is independent of the mechanism of transcorneal transport.