Development of performance matrix for generic product equivalence of acyclovir topical creams

Topical Semisolid Drug Product Critical Quality Attributes with Relevance to Cutaneous Bioavailability and Pharmacokinetics: Part I-Bioequivalence of Acyclovir Topical Creams

PURPOSE

To develop a toolkit of test methods for characterizing potentially critical quality attributes (CQAs) of topical semisolid products and to evaluate how CQAs influence the rate and extent of active ingredient bioavailability (BA) by monitoring cutaneous pharmacokinetics (PK) using an In Vitro Permeation Test (IVPT).

METHODS

Product attributes representing the physicochemical and structural (Q3) arrangement of matter, such as attributes of particles and globules, were assessed for a set of test acyclovir creams (Aciclostad® and Acyclovir 1A Pharma) and compared to a set of reference acyclovir creams (Zovirax® US, Zovirax® UK and Zovirax® Australia). IVPT studies were performed with all these creams using heat-separated human epidermis, evaluated with both, static Franz-type diffusion cells and a flow through diffusion cell system.

RESULTS

A toolkit developed to characterize quality and performance attributes of these acyclovir topical cream products identified certain differences in the Q3 attributes and the cutaneous PK of acyclovir between the test and reference sets of products. The cutaneous BA of acyclovir from the set of reference creams was substantially higher than from the set of test creams.

CONCLUSIONS

This research elucidates how differences in the composition or manufacturing of product formulations can alter Q3 attributes that modulate myriad aspects of topical product performance. The results demonstrate the importance of understanding the Q3 attributes of topical semisolid drug products, and of developing appropriate product characterization tests. The toolkit developed here can be utilized to guide topical product development, and to mitigate the risk of differences in product performance, thereby supporting a demonstration of bioequivalence (BE) for prospective topical generic products and reducing the reliance on comparative clinical endpoint BE studies.

Impact of active pharmaceutical ingredient variables and oleaginous base on the in vitro drug release from ophthalmic ointments: An investigation using dexamethasone as a model drug

The present study systematically investigates the impact of active pharmaceutical ingredient (API) variables and oleaginous base characteristics on the in vitro release (IVR) performance of ophthalmic ointments, utilizing dexamethasone as a model drug. The interplay between selected attributes (i.e., particle size distribution, crystallinity, and polymorphic form for API, and rheological factors for compendial-grade white petrolatum) and IVR performance was investigated. APIs from different vendors exhibited variations in crystallinity and polymorphism. Ointments containing amorphous dexamethasone presented higher release amounts/rates compared to crystalline counterparts, emphasizing the role of physical state in release kinetics. Variations in particle size of this lipophilic API (5.4 - 21.2 µm) did not appear to impact IVR performance significantly. In contrast, white petrolatum's rheological attributes, which varied substantially within USP-grade petrolatum, were found to critically affect the drug release rate and extent of the ointment. The study's comprehensive analysis establishes a coherent connection between the quality attributes of both API and petrolatum and IVR, delineating their intricate interdependent effects on ophthalmic ointment performance. These findings provide reference to formulation design, quality control, and regulatory considerations within the pharmaceutical industry, fostering a robust foundational understanding of commonly overlooked quality attributes in ophthalmic ointments.

Development and Validation of Matrix of Chemistry, Manufacturing, and Control (MoCMC) System for Intramammary Drug Products (IMM)

PURPOSE

Products formulated for intramammary (IMM) infusion are intended for the delivery of therapeutic moieties directly into the udder through the teat canal to maximize drug exposure at the targeted clinical site, the mammary gland, with little to no systemic drug exposure. Currently, to our knowledge, there has been no in-vitro matrix system available to differentiate between IMM formulations. Our goal is to develop A custom tailored in-vitro "Matrix of Chemistry, Manufacturing and Control" (MoCMC) System to be a promising future tool for identifying inequivalent IMM formulations. MoCMC can detect inter and intra batch variabilities, thereby identifying potential generics versus brand product similarities or differences with a single numeric value and a specific & distinctive fingerprint.

METHODS

The FDA-approved IMM formulation, SPECTRAMASTⓇ LC, was selected as the reference product for the MoCMC. Twelve in-house test formulations containing ceftiofur hydrochloride were formulated and characterized. The MoCMC was developed to include six input parameters and three output parameters. The MoCMC system was used to evaluate and compare SPECTRAMASTⓇ LC with its in-house formulations.

RESULTS

Based on the MoCMC generated parameters, the distinctive fingerprints of MoCMC for each IMM formulations, and the statistical analyses of MCI and PPI values, in-house formulations, F-01 and F-02 showed consistency while the rest of in-house formulations (F-03-F-12) were significantly different as compared to SPECTRAMASTⓇ LC.

CONCLUSION

This research showed that the MoCMC approach can be used as a tool for intra batch variabilities, generics versus brand products comparisons, post-approval formulations changes, manufacturing changes, and formulation variabilities.

Equivalence assessment of creams with quali-quantitative differences in light of the EMA and FDA regulatory framework

EMA and FDA are upgrading guidelines on assessing the quality and the equivalence of topically applied drug products for developing copies of originator products and supporting post-marketing variations. For topical products having remarkably similar composition, both EMA and FDA accept the equivalence on the bases of the comparison of rheological properties and in vitro drug release constant (k) and skin permeation flux (J) values, instead of clinical studies. This work aims to evaluate the feasibility to expand this approach to variations of the composition of complex semi-solid preparations. Ibuprofen (IB) creams at two different strengths (i.e., 1 % and 10 %) were used as a model formulation. Two formulative changes were performed: (a) the addition of the humectant to simulate a minor post-marketing variation; (b) the substitution of the emulsifying system to simulate a major one. These variations impacted only in 1 % IB formulations where both the equivalences of rheological data and J-values failed. At the highest concentration, the presence of IB crystals broke down the differences in rheological patterns and lead the IB thermodynamic activity at the maximum figuring out an overlapping of the J-values. Such data suggest the combination of these studies, which are thought mainly for the development of copies, could be also applied to the management of post-marketing variations that involve product composition.

QbD-assisted optimisation of liposomes in chitosan gel for dermal delivery of aceclofenac as synergistic approach to combat pain and inflammation

Aceclofenac (ACE) is a drug that was precisely devised to circumvent the shortcomings associated with diclofenac. However, ACE too corresponds to nonsteroidal anti-inflammatory drug (NSAID)-related adverse effects, but with a lower amplitude. The present investigation seeks to develop liposomes loaded with ACE adopting a central composite design (CCD) and formulate a chitosan-based hydrogel for synergistic anti-inflammatory efficacy and improved ACE dermal administration. On the basis of preliminary vesicle size, Poly Dispersity Index (PDI), and drug entrapment, the composition of lipid, cholesterol, and vitamin E TPGS were chosen as independent variables. The formulation composition met the specifications for an optimum liposomal formulation, with total lipid concentration (13.5% w/w), cholesterol concentration (10% w/w), and surfactant concentration (2% w/w). With particle size and PDI of 174.22 ± 5.46 nm and 0.285 ± 0.01 respectively, the optimised formulation achieved an entrapment effectiveness of 92.08 ± 3.56%. Based on the CCD design, the optimised formulation Acec-Lipo opt was chosen and was subsequently transformed to a chitosan-based gel formulation for in vitro drug release, penetration through the skin, in vivo analgesic therapeutic activity, and skin irritation testing. % age oedema inhibition was found to be greatest with the Acec-Lipo opt gel formulation, followed by Acec gel. These results reinforce the notion that the inclusion of chitosan resulted in a synergistic effect despite the same strength of the drug. The findings suggested that Acec-Lipo incorporated in chitosan gel for skin targeting might be an effective formulation for topical ACE administration in clinical subjects.

Development and Validation of Discriminatory In-vitro Release Method for Intramammary Drug Product

PURPOSE

Intramammary (IMM) formulations are locally acting and delivered intracisternally into the udder. No pharmacopeial in-vitro release method is available to differentiate between the IMM formulations. Our research aim is to develop in-vitro release methods that discriminate different IMM formulations (SPECTRAMAST® LC and in-house formulations).

METHODOLOGY

Different in-house formulations were developed to simulate SPECTRAMAST® LC generics. SPECTRAMAST® LC and the in-house formulations were characterized for physicochemical attributes, such as particle size, rheology, drug content, sedimentation rate, and flocculation rate. The in-vitro release method was optimized by evaluating drug release using USP apparatuses 1, 2 (with and without enhancer/customized cells), and 4. Various test parameters, including medium effect (whole homogenized bovine milk versus aqueous buffer), medium volume (200-900 mL), and rotational speed (50-200 rpm) were investigated.

RESULTS

Two potential in-vitro systems can be used as discriminatory methods for IMM formulations: USP apparatus 2 with the IMM formulation loaded into two containers a) customized formulation container (83.1 cm in height and 56.4 cm in width) or b) enhancer cells with their top adapted with mesh #40 (rotation speed:125 rpm and 900 mL of whole homogenized bovine milk). The release profile of SPECTRAMAST® LC at 1 h (99.8%) was not significantly different from formulations with similar physicochemical characteristics F-01 (99.1%) and F-02 (100.5%). Formulation with different physicochemical characteristics F-03 (44.3%) and F-04 (57.2%) showed slower release (1 h) than SPECTRAMAST® LC (98.8%).

CONCLUSION

The developed in-vitro release methods can be used as a potential tool for in-vitro comparability evaluations for IMM formulations.

Can Continuous Manufacturing of Topical Semisolids by Hot Melt Extrusion Soon Be a Reality?

For more than five decades, pharmaceutical manufacturers have been relying heavily on batch manufacturing that is a sequential, multistep, laborious, and time-consuming process. However, late advances in manufacturing technologies have prompted manufacturers to consider continuous manufacturing (CM) is a feasible manufacturing process that encompasses fewer steps and is less tedious and quick. Global regulatory agencies are taking a proactive role to facilitate pharmaceutical industries to adopt CM that assures product quality by employing robust manufacturing technologies encountering fewer interruptions, thereby substantially reducing product failures and recalls. However, adopting innovative CM is known to pose technical and regulatory challenges. Hot melt extrusion (HME) is one such state-of-the-art enabling technology that facilitates CM of diverse pharmaceutical dosage forms, including topical semisolids. Efforts have been made to continuously manufacture semisolids by HME integrating the principles of Quality by Design (QbD) and Quality Risk Management (QRM) and deploying Process Analytical Technologies (PAT) tools. Attempts have been made to systematically elucidate the effect of critical material attributes (CMA) and critical process parameters (CPP) on product critical quality attributes (CQA) and Quality Target Product Profiles (QTPP) deploying PAT tools. The article critically reviews the feasibility of one of the enabling technologies such as HME in CM of topical semisolids. The review highlights the benefits of the CM process and challenges ahead to implement the technology to topical semisolids. Once the CM of semisolids adopting melt extrusion integrated with PAT tools becomes a reality, the process can be extended to manufacture sterile semisolids that usually involve more critical processing steps.

Assessing and Predicting Physical Stability of Emulsion-Based Topical Semisolid Products: A Review

The emulsion-based topical semisolid dosage forms present a high degree of complexity due to their microstructures which is apparent from their compositions comprising at least two immiscible liquid phases, often times of high viscosity. These complex microstructures are thermodynamically unstable, and the physical stability of such preparations is governed by formulation parameters such as phase volume ratio, type of emulsifiers and their concentration, HLB value of the emulsifier, as well as by process parameters such as homogenizer speed, time, temperature etc. Therefore, a detailed understanding of the microstructure in the DP and critical factors that influence the stability of emulsions is essential to ensure the quality and shelf-life of emulsion-based topical semisolid products. This review aims to provide an overview of the main strategies used to stabilize pharmaceutical emulsions contained in semisolid products and various characterization techniques and tools that have been utilized so far to evaluate their long-term stability. Accelerated physical stability assessment using dispersion analyzer tools such as an analytical centrifuge to predict the product shelf-life has been discussed. In addition, mathematical modeling for phase separation rate for non-Newtonian systems like semisolid emulsion products has also been discussed to guide formulation scientists to predict a priori stability of these products.

Confocal Raman Spectroscopy for Assessing Bioequivalence of Topical Formulations

The evaluation of bioequivalence (BE) for topical dermatological drug products is challenging, and there has been significant interest from regulatory authorities in developing new BE methodologies in recent years. Currently, BE is demonstrated by comparative clinical endpoint studies; these are costly and time-consuming and often lack sensitivity and reproducibility. Previously, we reported excellent correlations between in vivo Confocal Raman Spectroscopy in human subjects and in vitro skin permeation testing (IVPT) with the human epidermis for skin delivery of ibuprofen and a number of excipients. The aim of the present proof-of-concept study was to evaluate CRS as a method to assess BE of topical products. Two commercially available formulations, Nurofen Max Strength 10% Gel and Ibuleve Speed Relief Max Strength 10% Gel, were selected for evaluation. Delivery of ibuprofen (IBU) to the skin was determined in vitro and in vivo by IVPT and CRS, respectively. The formulations examined were found to deliver comparable amounts of IBU across the skin over 24 h in vitro (p > 0.05). Additionally, the formulations resulted in similar skin uptake values measured with CRS in vivo, either at 1 h or 2 h after application (p > 0.05). This is the first study to report the capability of CRS for the demonstration of BE of dermal products. Future studies will focus on the standardisation of the CRS methodology for a robust and reproducible pharmacokinetic (PK)-based evaluation of topical BE.

Formulation and Evaluation of the In Vitro Performance of Topical Dermatological Products Containing Diclofenac Sodium

The selection of an appropriate vehicle in a semi-solid topical product is of utmost importance since the vehicle composition and microstructure can potentially cause changes in drug-vehicle or vehicle-skin interactions and affect drug release and subsequent permeation into and across skin. Hence, the aim of this study was to evaluate different semi-solid formulations containing diclofenac sodium for the physicochemical and structural performance of excipients used and various physiological factors governing permeation of drugs applied to skin. The formulations (emulsion, emulgel, gel, and ointment) were prepared using conventional excipients and were found to be homogenous and stable. Rheological analysis demonstrated characteristic shear-thinning and viscoelastic behavior of formulations. The mean release rate of the gel formulation (380.42 ± 3.05 µg/cm²/h^0.5) was statistically higher compared to all other formulations. In vitro permeation using human skin showed a significantly greater extent of drug permeation and retention for the emulgel formulation (23.61 ± 1.03 µg/cm² and 47.95 ± 2.47 µg/cm², respectively). The results demonstrated that the different formulations influenced product performance due to their inherent properties. The findings of this study demonstrated that a comprehensive physicochemical and structural evaluation is required to optimize the in vitro performance for dermatological formulations depending on the intended therapeutic effect.

API-polymer interactions in Sepineo P600 based topical gel formulation- impact on rheology

In the present study, topical gel and emulsion gel were formulated using Acrylamide/ Sodium Acryloyldimethyl taurate copolymer (Sepineo P600) as a gelling agent, and their rheological attributes and physical stability were evaluated upon incorporation of API. Lidocaine, a free base drug (pK_a 7.92) was used as a model drug in all formulations. Medium- chain Triglycerides (MCT) was used as a dispersed phase to prepare the emulgel. Results show that the rheological properties of both gel and emulgel such as viscosity, elastic moduli and yield stress were significantly influenced by the pH of the topical formulations and API concentration. A lower pH (pH < pKa) leads to the increase in number of cationic species of lidocaine, which results in the weakening of the structure of the gel matrix by charge screening of polymer-polymer repulsions. Interactions between API and polymer chains through electrostatic attraction may play a major role in altering the rheology, which could potentially impact the physical stability against phase separation of the internal phase in emulsion gel samples. This study provides valuable insights into rheological behaviors of Sepineo P600 gel and emulgel which can be modified or tuned though the interplay of the API properties and critical formulation parameters such as pH. The tunable rheological properties with simpler manufacturing process make Sepineo P600 gel and emulsion gel very suitable systems for use in semisolid topical formulations.

Pilot Equivalence Study Comparing Different Batches of Topical 0.025% Capsaicin Emulsion: Product Microstructure, Release, and Permeation Evaluation

The European Medical Agency (EMA) has issued a draft guideline on the quality and equivalence of topical products. The equivalence for complex semisolid formulations involves several steps: the same quantitative content, the same microstructure, the same release, and permeation profile. In this paper, several batches of a low strength topical product, which we used as a reference/comparator product, were evaluated according to the recommendations of the EMA draft guideline. The batches were 0.025% capsaicin emulsions from the same manufacturer that were evaluated in terms of droplet size, X-ray diffraction patterns, rheology, release, and permeation profile. The generated data revealed a large batch-to-batch variability, and if the EMA guideline was applied, these batches would not be considered equivalent, although they were produced by the same manufacturer. The result of this work illustrates the difficulties in obtaining equivalence according to the current draft guidelines. It also highlights that the equivalence guidelines should consider the variability of the comparator product, and in our opinion, the guidelines should allow for claiming equivalence by comparing the limits in the variability of the data generated for the comparator product with the limits in the variability of the data generated for the intended equivalence product.

Comparative in vitro release testing (IVRT) of acyclovir products

The aim was to evaluate whether an in vitro release test (IVRT) could differentiate the release rates from five pharmaceutically equivalent acyclovir cream products and one ointment compared to that from a reference product, Zovirax cream (USA), to identify a test product with an inequivalent drug release rate that could serve as negative control for bioequivalence (BE) in a separate in vivo study. The reference product showed equivalent drug release rates compared to itself. The six test products failed to show equivalent drug release rates compared to the reference product. Aciclovir 1A pharma cream was selected to serve as a negative control for subsequent BE studies, since it exhibited the greatest difference in release rate among all creams, compared to the reference product. The results of this study indicate that IVRT results can be highly sensitive and may discriminate clinically relevant differences between products. Results from an appropriately validated IVRT method can support a demonstration of BE by showing that the drug release rates from test and reference products are statistically equivalent, mitigating the risk that differences may exist between the products which may influence in vivo performance of the drug product.

Are European marketed acyclovir 5% cream products similar? Comparison with EU and US reference product

OBJECTIVE

The aim was to perform a comparative evaluation of composition and in vitro release performance of multisource acyclovir 5% creams.

SIGNIFICANCE

The outcome was analyzed in relation with the principles of the Topical drug Classification System (TCS).

METHODS

The in vitro drug release testing (IVRT) was based on selection of an inert artificial membrane and a medium providing sink conditions, and utilizing the vertical diffusion cells. US and European innovator products, with marked difference in excipients, were used as references for the assessment of the in vitro release similarity. The qualitative composition of the topical semisolid products was inventoried, with no quantitative details being available. A Principal Component Analysis was applied by either dichotomy ranking or grouping the individual excipients into categories according to their functional role.

RESULTS

The results confirmed the sensitivity and discriminative characteristics of IVRT with respect to the qualitative composition, as well as its relevance in the comparative assessment of multisource drug products beyond the current strict requirements of Q1 and Q2 similarity.

CONCLUSIONS

This is in line with the principles of the TCS and with the central role assigned to IVRT.

Rheological and in vitro release measurements of manufactured acyclovir 5% creams: confirming sensitivity of the in vitro release

Previous evaluation of marketed acyclovir 5% creams using in vitro release testing (IVRT) and its correlation with the qualitative composition confirmed the discriminative characteristics of this methodology. This was in line with the principles of Topical drug Classification System (TCS). For the current research, experimental formulations were designed and prepared by applying controlled changes in manufacturing process, sources of raw materials, and amount of the excipients. The topical semisolids were representative for the four classes of TCS. The outcome of the IVRT and rheological assessments was evaluated in relation with the nature of the change and the functional role of the excipients. The variations in propylene glycol content from 5% to 40% impacted both the in vitro release rates (gradual decrease from 16.23 to 8.97 µg/cm²/min^0.5) and the microstructural characteristics (proportional increase of yield stress from 17.98 to 46.40 Pa). The inert excipients e.g. cetostearyl alcohol or white soft paraffin altered majorly the rheological behavior, as their functionality is mainly related to vehicle properties. IVRT was discriminative for the microstructural differences induced by both categories of excipients according to TCS dichotomy. This simple, reliable, and reproducible test reflected the impact of difference in quantitative composition and characteristics of excipients.

Interfacial Effects and the Nano-Scale Disruption in Adsorbed-Layer of Acrylate Polymer-Tween 80 Fabricated Steroid-Bearing Emulsions: A Rheological Study of Supramolecular Materials

The effect of polymer adsorption on the stability and viable shelf life of 55 μm diameter oil-in-water (O/W) emulsions containing the steroid, betamethasone 21-phosphate was investigated. Two acrylate polymers, Carbopol^® 971P and 974P, were added in the role of emulsion stabilizers to a model system, representing a non-ionic low molecular weight surfactant-stabilized emulsion (topically applied medicinal cream). For the purposes of this study the dosage of the viscosifier was maintained below 1% w/v and consequently, the consistency of the emulsion was measured in the diluted form. One of the polymers was responsible for elevated degrees of droplet creaming and coalescence and this was closely linked to its surface tension lowering capacity. This lowering was seen at 62 mN/m compared to the routine values at equivalent concentrations of 68 mN/m and 35 mN/m for the betamethasone drug and non-ionic surfactant-Tween 80, respectively. The same polymer also demonstrated a predisposition to form low-micron and greater sized aggregates of nanoparticles that led to extensive flocculation and the formation of a sedimentary precipitate, formed from an amalgam of the components found in the creamed droplet layer.

The Implications of Regulatory Framework for Topical Semisolid Drug Products: From Critical Quality and Performance Attributes towards Establishing Bioequivalence

Due to complex interdependent relationships affecting their microstructure, topical semisolid drug formulations face unique obstacles to the development of generics compared to other drug products. Traditionally, establishing bioequivalence is based on comparative clinical trials, which are expensive and often associated with high degrees of variability and low sensitivity in detecting formulation differences. To address this issue, leading regulatory agencies have aimed to advance guidelines relevant to topical generics, ultimately accepting different non-clinical, in vitro/in vivo surrogate methods for topical bioequivalence assessment. Unfortunately, according to both industry and academia stakeholders, these efforts are far from flawless, and often upsurge the potential for result variability and a number of other failure modes. This paper offers a comprehensive review of the literature focused on amending regulatory positions concerning the demonstration of (i) extended pharmaceutical equivalence and (ii) equivalence with respect to the efficacy of topical semisolids. The proposed corrective measures are disclosed and critically discussed, as they span from mere demands to widen the acceptance range (e.g., from ±10% to ±20%/±25% for rheology and in vitro release parameters highly prone to batch-to-batch variability) or reassess the optimal number of samples required to reach the desired statistical power, but also rely on specific data modeling or novel statistical approaches.

Complying with the Guideline for Quality and Equivalence for Topical Semisolid Products: The Case of Clotrimazole Cream

Semisolids constitute a significant proportion of topical pharmaceutical dosage forms available on the market, with creams being considered profitable systems for releasing active substances into the skin. This work aimed at the development of a generic Clotrimazole topical cream, based on the assumptions that assist the development of such formulations. First, the critical parameters to obtain a final formulation as similar as possible to the reference product were defined. Then, the percentages of cetyl palmitate and octyldodecanol were identified as critical variables and chosen for optimization in further studies. A "quality by design" approach was then used to identify the effect of process variability on the structural and functional similarity (Q3) of the generic product qualitatively (Q1) and quantitatively (Q2). A two-factor central composite orthogonal design was applied and eleven different formulations were developed and subjected to physicochemical characterization and product performance studies. The results were used to estimate the influence of the two variables in the variation of the responses, and to determine the optimum point of the tested factors, using a design space approach. Finally, an optimized formulation was obtained and analysed in parallel with the reference. The obtained results agreed with the prediction of the chemometric analysis, validating the reliability of the developed multivariate models. The in vitro release and permeation results were similar for the reference and the generic formulations, supporting the importance of interplaying microstructure properties with product performance and stability. Lastly, based on quality targets and response constraints, optimal working conditions were successfully achieved.

Effect of surfactant on quality and performance attributes of topical semisolids

Surfactants are the most common inactive ingredients used in topical drug products. Surfactants in topical products play many functional roles such as emulsifiers, permeation enhancers, and solubilizers. This study was aimed to evaluate the influence of incremental change in the concentration of a surfactant (tween 80) on the quality attributes and performance of semisolid topical products. Four creams were prepared using metronidazole as a model drug using the same manufacturing protocol and similar composition except for the concentration of tween 80, which was increased by 5% w/w across SF1 to SF4. The quality attributes like globule size, pH, drying rate, and in-vitro permeation profile were characterized. The critical quality attributes did not differ significantly across the products. However, there was a significant difference in the permeation profile of the products. The permeation flux (J_max) varied from SF1 to SF4 (51.25 ± 35.29 to 307.98 ± 138.89 ng/cm²/h, respectively). The reason for the difference in the performance of products despite having consistent quality attributes was investigated. One of the major reasons was found to be the difference in the time course of degree of saturation of drug during the evaporative metamorphosis. This study confirms that the time course of degree of saturation is one of the important quality attributes of the topical product that could influence bioavailability and performance of topical products.

Diving into Batch-to-Batch Variability of Topical Products-a Regulatory Bottleneck

PURPOSE

Following the recent European Medicine Agency (EMA) draft guideline on quality and equivalence of topical products, a modular framework for bioequivalence assessment is proposed, wherein the qualitative, quantitative, microstructure and product performance sameness is demanded to support generic applications. Strict regulatory limits are now imposed, but, the suitability of these limits has been subject of intense debate. In this context, this paper aims to address these issues by characterizing a panel of 8 reference blockbuster semisolid topical products.

METHODS

For each product, three batches were selected and, whenever possible, batches retrieved from different manufacturing sites were considered. Product microstructure was evaluated in terms of globule size, pH, rheological attributes and, if required, the thermal behaviour was also assessed. Performance was evaluated through in vitro release testing (IVRT). Finally, an integrated multivariate analysis was performed to highlight the features that most contribute for product variability.

RESULTS

Marked differences were registered within reference products. Statistical analysis demonstrated that if EMA criteria are applied, none of the same product batches can be considered as equivalent. Rheological parameters as well as IVRT indicators account for the majority of batch-to-batch differences.

CONCLUSIONS

Semisolid dosage forms exhibit intrinsic variability. This calls for the attention to the need of establishing reasonable equivalence criteria applied to generic drug products. Graphical abstract.

In Vitro Release Testing of Acyclovir Topical Formulations Using Immersion Cells

The objective of the study was to reinforce the applicability of the immersion cells for the in vitro release testing (IVRT) of topical formulations by using marketed acyclovir 5% cream formulation (Cream 1) as a model. The method employing the immersion cells was optimized by studying the effect of variables, such as membrane type, media temperature and volume, agitation speed, and cell size, on acyclovir release from the formulation. The in-house formulation similar to the qualitative and quantitative composition of Cream 1 and the other trial formulations with variable compositions were prepared and studied by using the immersion cells. Various other brands of acyclovir topical formulations available in the Indian market were also subjected to IVRT by using the optimized method. An increase in the media temperature from 32°C to 37°C and the stirring speed from 50 to 100 to 150 rpm led to an increase in the drug release. As the immersion cell size increased (0.5, 2 and 4 cm² surface area), the release rate also increased. Nitrocellulose membrane showed the highest drug release and Fluoropore^™ the least. The optimized IVRT method could establish the differences in the drug release rates among the formulations with the altered compositions. The method could also prove its discriminatory potential for various marketed formulations. The immersion cell method could serve as a simpler, facile, and reliable aid during product development and also as a quality control tool in assessing stability, aging, and batch-to-batch uniformity of semisolid formulations.

Influence of in vitro release methods on assessment of tobramycin ophthalmic ointments

The current investigation was carried out to identify appropriate parameters for measuring the in vitro release of tobramycin (TOB) ophthalmic ointments and to evaluate the feasibility of in vitro release testing methods to assess the product performance. Drug release was assessed using USP dissolution apparatus IV and a modified USP dissolution apparatus I with simulated tear solution (STS) as the dissolution medium. The study variables included temperature, membrane material, source and pore size. The results demonstrated a significant influence of the membrane source and pore size on the release of TOB from the ointments. A dissolution medium temperature of 40 °C was found to be appropriate for the release studies. Both of the apparatuses were able to discriminate between the release profiles of ointments with different physicochemical/rheological properties. Maximum release rate of TOB was observed in the first hour which followed a logarithmic time dependent release. The correlation between the release rates/amounts and yield stress of the ointments was observed in both the dissolution apparatuses. These results support a rational approach to guide the in vitro release testing of TOB ophthalmic ointments.

Variability of Skin Pharmacokinetic Data: Insights from a Topical Bioequivalence Study Using Dermal Open Flow Microperfusion

PURPOSE

Dermal open flow microperfusion (dOFM) has previously demonstrated its utility to assess the bioequivalence (BE) of topical drug products in a clinical study. We aimed to characterize the sources of variability in the dermal pharmacokinetic data from that study.

METHODS

Exploratory statistical analyses were performed with multivariate data from a clinical dOFM-study in 20 healthy adults evaluating the BE, or lack thereof, of Austrian test (T) and U.S. reference (R) acyclovir cream, 5% products.

RESULTS

The overall variability of logAUC values (CV: 39% for R and 45% for T) was dominated by inter-subject variability (R: 82%, T: 91%) which correlated best with the subject's skin conductance. Intra-subject variability was 18% (R) and 9% (T) of the overall variability; skin treatment sites or methodological factors did not significantly contribute to that variability.

CONCLUSIONS

Inter-subject variability was the major component of overall variability for acyclovir, and treatment site location did not significantly influence intra-subject variability. These results support a dOFM BE study design with T and R products assessed simultaneously on the same subject, where T and R treatment sites do not necessarily need to be next to each other. Localized variation in skin microstructure may be primarily responsible for intra-subject variability.

Franz Cell Diffusion Testing and Quantitative Confocal Raman Spectroscopy: In Vitro-In Vivo Correlation

Previously, we reported the use of Confocal Raman Spectroscopy (CRS) to investigate the topical delivery of actives and excipients. We have also correlated the results from CRS with findings from in vitro diffusion studies in human skin. However, until now CRS has only been used as a semi-quantitative method of determining the skin uptake of molecules, with results expressed as arbitrary units of signal intensity. Clearly, this posed challenges for using CRS to determine skin delivery and to assess the drug bioavailability and bioequivalence of topical formulations. In the present work, the permeation of niacinamide (NIA) from various formulations in human skin was studied in vitro using conventional Franz cells and in vivo using a quantitative CRS method under finite dose conditions. The selection of NIA was based on its wide use in pharmaceutical and personal care formulations for many years. This is the first fully quantitative study to compare these methods. The vehicles investigated were neat Transcutol^® P (TC); binary combinations of propylene glycol (PG) with propylene glycol monolaurate (PGML); and ternary mixtures of PG, PGML, and isopropyl myristate (IPM). These solvents were selected to encompass a range of physicochemical properties. NIA permeation was evident from all formulations in vitro and in vivo. The vehicles PG:PGML and PG:PGML:IPM delivered comparable amounts across the skin in vitro at 24 h (100.3–106.7 µg/cm², p > 0.05) that were significantly higher compared with those of TC (1.3 µg/cm², p < 0.05). An excellent in vitro in vivo correlation (R² = 0.98) was found following the linear regression of the cumulative amounts of NIA permeated in vitro and the amounts of NIA at 2 μm in the skin measured with CRS. A very good correlation between the cumulative permeation of NIA in vitro and the total amount of NIA that penetrated the stratum corneum (SC) per unit of surface area (μg/cm²) in vivo was also observed, with a Pearson correlation coefficient (R²) of 0.94. The findings support the use of CRS for the quantitative measurement of actives delivered to the skin in vivo. Future studies will focus on exploring the reproducibility and reliability of the method by investigating the delivery of different actives from a wider range of vehicles. Additionally, quantitative CRS will be evaluated further as a method for assessing the bioequivalence of topical formulations.

Rheology by Design: A Regulatory Tutorial for Analytical Method Validation

The increasing demand for product and process understanding as an active pursuit in the quality guideline Q8 and, more recently, on the draft guideline on quality and equivalence of topical products, has unveiled the tremendous potential of rheology methods as a tool for microstructure characterization of topical semisolid dosage forms. Accordingly, procedure standardization is a dire need. This work aimed at developing and validating a methodology tutorial for rheology analysis. A 1% hydrocortisone cream was used as model cream formulation. Through a risk assessment analysis, the impact of selected critical method variables (geometry, temperature and application mode) was estimated in a broad range of rheological critical analytical attributes-zero-shear viscosity, upper-shear thinning viscosity, lower-shear thinning viscosity, infinite-shear viscosity, rotational yield point, thixotropic relative area, linear viscoelastic region, oscillatory yield point, storage modulus, loss modulus, and loss tangent. The proposed validation of the approach included the rheometer qualification, followed by the validation of numerous operational critical parameters regarding a rheology profile acquisition. The thixotropic relative area, oscillatory yield point, flow point and viscosity related endpoints proved to be highly sensitive and discriminatory parameters. This rationale provided a standard framework for the development of a reliable and robust rheology profile acquisition.

Progressing Towards the Sustainable Development of Cream Formulations

This work aims at providing the assumptions to assist the sustainable development of cream formulations. Specifically, it envisions to rationalize and predict the effect of formulation and process variability on a 1% hydrocortisone cream quality profile, interplaying microstructure properties with product performance and stability. This tripartite analysis was supported by a Quality by Design approach, considering a three-factor, three-level Box-Behnken design. Critical material attributes and process parameters were identified from a failure mode, effects, and criticality analysis. The impact of glycerol monostearate amount, isopropyl myristate amount, and homogenization rate on relevant quality attributes was estimated crosswise. The significant variability in product droplet size, viscosity, thixotropic behavior, and viscoelastic properties demonstrated a noteworthy influence on hydrocortisone release profile (112 ± 2–196 ± 7 μg/cm²/√h) and permeation behavior (0.16 ± 0.03–0.97 ± 0.08 μg/cm²/h), and on the assay, instability index and creaming rate, with values ranging from 81.9 to 120.5%, 0.031 ± 0.012 to 0.28 ± 0.13 and from 0.009 ± 0.000 to 0.38 ± 0.07 μm/s, respectively. The release patterns were not straightforwardly correlated with the permeation behavior. Monitoring the microstructural parameters, through the balanced adjustment of formulation and process variables, is herein highlighted as the key enabler to predict cream performance and stability. Finally, based on quality targets and response constraints, optimal working conditions were successfully attained through the establishment of a design space.

Fast Screening Methods for the Analysis of Topical Drug Products

Considering the recent regulatory requirements, the overall importance of in vitro release testing (IVRT) methods regarding topical product development is undeniable, especially when addressing particulate systems. For each IVRT study, several hundreds of samples are generated. Therefore, developing rapid reversed-phase high-performance liquid chromatography (RP-HPLC) methods, able to provide a real-time drug analysis of IVRT samples, is a priority. In this study, eight topical complex drug products exhibiting distinct physicochemical profiles were considered. RP-HPLC methods were developed and fully validated. Chromatographic separations were achieved on a XBridgeTM C18 (5 µm particle size, 150 mm × 2.1 mm), or alternatively on a LiChrospher® 100 RP-18 (5 µm particle size, 125 mm × 4.6 mm) at 30 °C, under isocratic conditions using UV detection at specific wavelengths. According to the physicochemical characteristics of each drug, different mobile phases were selected. Irrespective of the drug (hydrocortisone, etofenamate, bifonazole, clotrimazole, acyclovir, tioconazole, clobetasol, and diclofenac) and formulation, retention time values did not exceed 6.5 min. All methods were linear, specific, precise, and accurate at the intraday and interday levels, robust, and stable. These were successfully applied to establish product-specific IVRT profiles, thus providing a key database useful for topical pharmaceutical manufacturers.

Quality and equivalence of topical products: A critical appraisal

The approval of topical generic products is essentially governed by clinical endpoint studies. Is this the most efficient approach to document bioequivalence in these particular dosage forms? This issue has sparked multiple discussions among different stakeholders - academia, industry and several regulatory agencies - in the active pursuit for new and robust surrogate methodologies. This mini review attempts to critically discuss this topic in light of the recently issued European regulatory requirements within the proposed modular framework for bioequivalence assessment.

aQbD as a platform for IVRT method development - A regulatory oriented approach

The EMA draft guideline on quality and equivalence of topical products and the FDA non-binding product specific guidances release has encouraged the establishment of a regulatory background for in vitro release testing (IVRT). Herein, a novel framework applicable to the development of a discriminatory IVRT method is described, according to analytical quality by design (aQbD) principles. A commercially available diclofenac emulgel formulation was used as model product. Through the definition of IVRT analytical target profile, a risk assessment analysis was carried out, in which the critical analytical attributes (in vitro release rate, cumulative amount released at an initial/final point and dose depletion) and critical method variables (medium, membrane and dosage regimen) were identified. Based on this information, a 3 × 2 × 3 full factorial design was performed. Statistical modeling and system desirability assessment enabled the selection of the most suitable IVRT parameters, which were fully validated according with new EMA requirements. These consisted of PBS:Ethanol (80:20, pH = 7.4), Tuffryn membranes and 300 mg of applied product. aQbD provided a comprehensive framework for developing a reliable and effective IVRT method. A thorough analysis of the new EMA draft guideline requirements revealed that some of the established criteria may be challenging to attain.

Developing Cream Formulations: Renewed Interest in an Old Problem

This work aimed at establishing a framework to screen and understand the product variability deeming from factors that affect the quality features of cream formulations. As per Quality by Design - based approach, cream quality target profile and critical quality attributes were identified, and a risk assessment analysis was conducted to qualitatively detect the most critical variables for cream design and development. A Plackett-Burman design was used to screen out unimportant factors, avoiding collecting large amounts of data. Accordingly, 2 designs of experiments (DoE-1 and DoE-2) were performed, and the effects of independent variables on the cream formulations responses were estimated. At different factor combinations, significant variability was observed in droplet size, consistency, hardness, compressibility, and adhesiveness with values ranging from 2.6 ± 0.9 to 10 ± 6 μm, 7.93 ± 0.05 to 13.53 ± 0.14 mm, 27.6 ± 0.3 to 58.4 ± 1.1 g, 38 ± 6 to 447 ± 37 g.s, and 25.7 ± 2.1 to 286 ± 33 g.s, respectively. The statistical analysis allowed determining the most influent factors. This study revealed the potential of Quality by Design methodology in understanding product variability, recognizing the most critical independent variables for the final product quality. This systematic approach in the pharmaceutical field will yield more robust products and processes, provisioning time and cost effective developments.

A quality by design approach to develop topical creams via hot-melt extrusion technology

The advantages of hot-melt extrusion technology (HME) over conventional techniques to develop topical semisolids have been established. However, this technique is not widely used for semisolid production. Therefore, the aim of this novel work was to develop creams using the melt extrusion technology while applying Quality by Design (QbD) principles to study the effects of the extrusion process parameters on the product characteristics. The model drug selected was hydrocortisone acetate. A 2³ factorial design was considered for the factor influence study, which resulted in eight formulations to be extruded. Of the process parameters considered, the temperature of zone 2 had a significant influence on the work of adhesion of the creams. A similar permeation profile was obtained for all the formulations with the formulations following a diffusion based drug release mechanism. The results from the size distribution graph indicated stable cream formulations. In conclusion, this technology coupled with a design of experiments approach could be utilized to study how the extrusion process parameters could be modified to develop consistent topical creams with ideal product characteristics.

Nanostructuring lipid carriers using Ridolfia segetum (L.) Moris essential oil

The therapeutic potential of essential oils is widely recognized since antiquity, due to their antibacterial, antifungal, anti-inflammatory and immuno-modulatory properties. In particular, their physicochemical characteristics, such as lipophilicity and permeation enhancement effect have sparked attention for the development of innovative lipid nanosystems. The present work aimed at developing a differentiated nanostructured lipid carrier (NLC) based formulation for topical application, using the Ridolfia segetum essential oil (REO), isolated by hydrodistillation from this Portuguese aromatic plant, with a dual key function, as active and simultaneously nanostructuring component of the nanoparticles. The incorporation of the essential oil in the solid lipid matrix, followed by the respective hot high-pressure homogenization, led to particles with a size of 143 ± 5 nm, along with a polydispersity index of 0.21, a zeta potential of -16.3 ± 0.6 mV, encapsulation efficacy of ca. 100% and loading capacity of 1.4%. A comprehensive physicochemical characterization of the lipid nanosystem, including morphology, structural, thermal and accelerated stability analysis confirmed its nanostructured nature. REO-NLC was further jellified for designing an appropriate semisolid topical dosage form. In vitro release, permeation and skin retention studies evidenced a sustained release behaviour and a reservoir-like effect, suitable for a prolonged topical delivery. Cytotoxicity studies, performed in fibroblasts and keratinocytes, revealed the biocompatibility of the developed formulations. This work highlights the critical role of REO as a multiaddressable compound, both as active pharmaceutical ingredient and nanostructuring agent, able to tailor the permeation enhancement profile of nanoparticles towards topical delivery purposes and concomitantly presenting a safety profile for cosmetic and/or pharmaceutical purposes.

Innovation for Generic Drugs: Science and Research Under the Generic Drug User Fee Amendments of 2012

Regulatory science is science and research intended to improve decision making in a regulatory framework. Improvements in decision making can be in both accuracy (making better decisions) and in efficiency (making faster decisions). Science and research supported by the Generic Drug User Fee Amendments of 2012 (GDUFA) have focused on two innovative methodologies that work together to enable new approaches to development and review of generic drugs: quantitative models and advanced in vitro product characterization. Quantitative models faithfully represent current scientific understanding. They are tools pharmaceutical scientists and clinical pharmacologists use for making better and faster product development decisions. Advances in the in vitro product comparisons provide the measurements of product differences that are the critical input into the models. This paper outlines four areas where science and research funded by GDUFA support synergistic use of models and characterization at critical decision points during generic drug product development and review.

Biopharmaceutical Development of a Bifonazole Multiple Emulsion for Enhanced Epidermal Delivery

Efficient topical delivery of imidazolic antifungals faces the challenge of overcoming its limited water solubility and its required long-lasting duration of treatments. In this paper, a hydrophilic multiple emulsion (ME) of Bifonazole (BFZ) is shown to maximize its skin retention, minimize its skin permeation, and maintain an acceptable level of being harmless in vivo. The formulations were pharmaceutically characterized and application properties were assessed based on viscosity measurements. Non-Newtonian pseudoplastic shear thinning with apparent thixotropy was observed, facilitating the formulation retention over the skin. The in vitro release profile with vertical diffusion cells showed a predominant square-root release kinetic suggesting an infinite dose depletion from the formulation. Ex vivo human skin permeation and penetration was additionally evaluated. Respective skin permeation was lower than values obtained with a commercial O/W formulation. The combination of amphoteric and non-ionic surfactants increased the bifonazole epidermal accumulation by a factor of twenty. This fact makes the possibility of increasing its current 24 h administration frequency more likely. Eventual alterations of skin integrity caused by the formulations were examined with epidermal histological analysis and in vivo preclinical measurements of skin elasticity and water retrograde permeation. Histological analysis demonstrated that the multiple emulsions were harmless. Additionally, modifications of in vivo skin integrity descriptors were considered as negligible.

Influencing factors on gelatin matrix for chlorhexidine delivery

OBJECTIVE

The objective was to evaluate the influencing factors in the fabrication of gelatin matrix (gelatin chips) for drug delivery. The attributes affecting drug release characteristics of the gelatin products were examined.

SIGNIFICANCE

Understanding the attributes that affect drug release from gelatin matrix could provide the knowledge base for the development, manufacturing, and performance evaluation of gelatin-based drug products for sustained drug delivery.

METHODS

Chlorhexidine (CHX) was the model drug in the gelatin-product testing. The gelatin products were fabricated by two methods: a single-pot mixing of all the components and a two-step gelatin crosslinking followed by drug loading. Different gelatin types (Type A porcine and Type B bovine), glutaraldehyde (GTA) crosslinking conditions, glycerin concentration, and CHX concentration in drug loading and loading time were used to fabricate the products. The cumulative amounts of CHX release from the gelatin products were determined using in vitro release testing (IVRT).

RESULTS

The attributes affecting CHX release from the gelatin products were gelatin type, GTA crosslinking, and CHX loading concentration. The fabrication methods (two-step method of gelatin crosslinking and drug loading by equilibration vs. direct mixing of the components) also affected CHX release. Other attributes such as glycerin and CHX loading time did not show significant effects on drug release under the conditions studied. In addition, the results in the two IVRT methods employed in this study were comparable.

CONCLUSION

Gelatin products of qualitative (Q1) and quantitative (Q2) differences could lead to different drug release behaviors. Drug release was also affected by the ingredient mixing steps during gelatin chip fabrication.

Perspectives on Physicochemical and In Vitro Profiling of Ophthalmic Ointments

Ophthalmic ointments are unique in that they combine features of topical drug delivery, the ophthalmic route and ointment (semisolid) formulations. Accordingly, these complex formulations are challenging to develop and evaluate and therefore it is critically important to understand their physicochemical properties as well as their in vitro drug release characteristics. Previous reports on the characterization of ophthalmic ointments are very limited. Although there are FDA guidance documents and USP monographs covering some aspects of semisolid formulations, there are no FDA guidance documents nor any USP monographs for ophthalmic ointments. This review summarizes the physicochemical and in vitro profiling methods that have been previously reported for ophthalmic ointments. Specifically, insight is provided into physicochemical characterization (rheological parameters, drug content and content uniformity, and particle size of the API in the finished ointments) as well as important considerations (membranes, release media, method comparison, release kinetics and discriminatory ability) in in vitro release testing (IVRT) method development for ophthalmic ointments. Graphical Abstract Summary of the physicochemcial profiling and in vitro drug release testing (IVRT) for ophthalmic ointments.

Bioequivalence of topical generic products. Part 2. Paving the way to a tailored regulatory system

Hitherto, for the approval of a topical generic drug product, the majority of the regulatory agencies require clinical endpoint studies to prove its therapeutic equivalence in relation to a reference product. Pharmacodynamic studies are also available to support bioequivalence, however, these are solely applicable for corticosteroids. The first strategy is considered the "gold standard", since it can be applied to all drug products. Nevertheless, the high variability intrinsic to topical drug delivery makes this analysis relatively insensitive, costly, time-consuming, besides requiring a large number of subjects. There are, however, alternative methods capable of providing a more rigorous analysis and requiring a lower cost. Amongst them, in vitro methods have sparked considerable attention, not only in the academic field, but also in the pharmaceutical industry and regulatory agencies. In this context, this review attempts to discuss the main regulatory constraints and the recent advances in the regulatory science of topical generic drugs bioequivalence assessment. Initiatives, such as the Strawman decision tree and the topical drug classification system are specially referred, since these highlight the importance of establishing a broader concept of pharmaceutical equivalence for topical generic drugs, similar to the one already set for orally administered conventional dosage forms, such as tablets and capsules. Finally, the FDA Product-Specific Guidances for Generic Drug Development released for topical products in recent years and particular European Public Assessment Reports are presented and discussed, to illustrate the change of paradigm which is occurring in this regulatory field.

A Tutorial for Developing a Topical Cream Formulation Based on the Quality by Design Approach

The pharmaceutical industry has entered in a new era, as there is a growing interest in increasing the quality standards of dosage forms, through the implementation of more structured development and manufacturing approaches. For many decades, the manufacturing of drug products was controlled by a regulatory framework to guarantee the quality of the final product through a fixed process and exhaustive testing. Limitations related to the Quality by Test system have been widely acknowledged. The emergence of Quality by Design (QbD) as a systematic and risk-based approach introduced a new quality concept based on a good understanding of how raw materials and process parameters influence the final quality profile. Although the QbD system has been recognized as a revolutionary approach to product development and manufacturing, its full implementation in the pharmaceutical field is still limited. This is particularly evident in the case of semisolid complex formulation development. The present review aims at establishing a practical QbD framework to describe all stages comprised in the pharmaceutical development of a conventional cream in a comprehensible manner.

Formulation characteristics and in vitro release testing of cyclosporine ophthalmic ointments

The aim of the present study was to investigate the relationship between formulation/process variables versus the critical quality attributes (CQAs) of cyclosporine ophthalmic ointments and to explore the feasibility of using an in vitro approach to assess product sameness. A definitive screening design (DSD) was used to evaluate the impact of formulation and process variables. The formulation variables included drug percentage, percentage of corn oil and lanolin alcohol. The process variables studied were mixing temperature, mixing time and the method of mixing. The quality and performance attributes examined included drug assay, content uniformity, image analysis, rheology (storage modulus, shear viscosity) and in vitro drug release. Of the formulation variables evaluated, the percentage of the drug substance and the percentage of corn oil in the matrix were the most influential factors with respect to in vitro drug release. Conversely, the process parameters tested were observed to have minimal impact. An evaluation of the release mechanism of cyclosporine from the ointment revealed an interplay between formulation (e.g. physicochemical properties of the drug and ointment matrix type) and the release medium. These data provide a scientific basis to guide method development for in vitro drug release testing of ointment dosage forms. These results demonstrate that the in vitro methods used in this investigation were fit-for-purpose for detecting formulation and process changes and therefore amenable to assessment of product sameness.

Development of poloxamer gel formulations via hot-melt extrusion technology

Poloxamer gels are conventionally prepared by the "hot" or the "cold" process. But these techniques have some disadvantages such as high energy consumption, requires expensive equipment and often have scale up issues. Therefore, the objective of this work was to develop poloxamer gels by hot-melt extrusion technology. The model drug selected was ketoprofen. The formulations developed were 30% and 40% poloxamer gels. Of these formulations, the 30% poloxamer gels were selected as ideal gels. DSC and XRD studies showed an amorphous nature of the drug after extrusion. It was observed from the permeation studies that with increasing poloxamer concentration, a decrease in drug permeation was obtained. Other studies conducted for the formulations included in-vitro release studies, texture analysis, rheological studies and pH measurements. In conclusion, the hot-melt extrusion technology could be successfully employed to develop poloxamer gels by overcoming the drawbacks associated with the conventional techniques.