Effect of surfactant on the in vitro dissolution and the oral bioavailability of a weakly basic drug from an amorphous solid dispersion

Effect of food on oral pharmacokinetics of edaravone coamorphous dispersion containing bile salts as coformers - Part II

OBJECTIVES

Edaravone (EDR) is an effective neuroprotective agent in various neurological diseases; however, its use is restricted due to poor oral absorption. Bile salts are known for improving solubility and inhibiting drug crystallization in supersaturated conditions of the gastrointestinal tract (GIT). In our previous work, we prepared coamorphous dispersion (COAM) of EDR with sodium taurocholate (NaTC) using spray drying. The optimized EDR COAM exhibited superior in vitro performance compared to plain EDR. EDR is well absorbed in fasted-over-fed conditions.

METHODS

The present work, we conducted a pharmacokinetic study for EDR and EDR COAM in fasted and fed conditions to check effect of food on its oral absorption. The LC-MS/MS-based method was developed and validated to determine the amount of EDR in plasma.

RESULTS

The results suggested that EDR COAM did not show a significant difference in Cmax (P=0.3544) and AUC (P=0.1696) of fasted and fed states. On the other hand, plain EDR showed 2-fold and 3-fold reduced Cmax (P<0.0001) and AUC (P=0.0094) in the fed condition, respectively. The Cmax and AUC of EDR COAM were improved in fasted (AUC: 2.56-fold) and fed states (AUC: 5.74-fold) than plain EDR, suggesting better oral absorption of COAM than crystalline EDR without having the effect of food.

CONCLUSIONS

The unique structural attributes of NaTC had the potential to inhibit the recrystallization of EDR in GIT, while concurrently reducing the impact of food on the oral absorption of EDR.

Synergistic effect of polymers in stabilizing amorphous pretomanid through high drug loaded amorphous solid dispersion

Pretomanid (PTM), an oral antibiotic used in the treatment of adults with pulmonary extensively drug-resistant, nonresponsive multidrug-resistant tuberculosis (MDR-TB). It is a poor glass former, that shows high recrystallization tendency from the amorphous and supersaturated state, resulting in low aqueous solubility and suboptimal absorption through the gastrointestinal tract. The present investigation aimed to develop high drug loaded ternary amorphous solid dispersions (ASDs) of PTM with improved stability and enhanced biopharmaceutical performance by utilizing a combination of polymers. The polymers were comprehensively screened based on drug-polymer miscibility and saturation solubility analysis. A combination of Hydroxypropyl Methylcellulose Acetate Succinate (HPMCAS-HF) and Polyvinylpyrrolidone K-30 (PVP K-30) showed synergism in drug-polymer miscibility as evidenced through pronounced depression in the melting endotherm of PTM. The Powder X-ray Diffraction (P-XRD) diffractograms of 30% w/w PTM loaded ternary ASDs displayed the halo pattern, contrary to the binary ASDs. Drug-polymer interactions (hydrophobic forces) involved between PTM and polymers were detected through Fourier Transform Infrared Spectroscopy (FT-IR) and Nuclear Magnetic Resonance Spectroscopy (13C-NMR) which contributed to the synergistic enhancement in solubility and dissolution of ternary ASDs with sustained release over 12 h. Ternary ASDs demonstrated better in-vivo performance compared to the binary ASDs, showing a 4.63-fold increase in maximum plasma concentration. All ASDs remained stable and resisted phase separation during short-term stability studies for 3 months at ambient conditions. It was concluded that the hydrophobic and hydrophilic polymeric combination (HPMCAS-HF and PVP K-30, respectively) effectively prevented the crystallization and ensured sustained drug release with improved in-vivo absorption of PTM.

Drug Release from Surfactant-Containing Amorphous Solid Dispersions: Mechanism and Role of Surfactant in Release Enhancement

PURPOSE

To understand how surfactants affect drug release from ternary amorphous solid dispersions (ASDs), and to investigate different mechanisms of release enhancement.

METHODS

Ternary ASDs containing ritonavir (RTV), polyvinylpyrrolidone/vinyl acetate (PVPVA) and a surfactant (sodium dodecyl sulfate (SDS), Tween 80, Span 20 or Span 85) were prepared with rotary evaporation. Release profiles of ternary ASDs were measured with surface normalized dissolution. Phase separation morphologies of ASD compacts during hydration/dissolution were examined in real-time with a newly developed confocal fluorescence microscopy method. The water ingress rate of different formulations was measured with dynamic vapor sorption. Microscopy was employed to check for matrix crystallization during release studies.

RESULTS

All surfactants improved drug release at 30% DL, while only SDS and Tween 80 improved drug release at higher DLs, although SDS promoted matrix crystallization. The dissolution rate of neat polymer increased when SDS and Tween 80 were present. The water ingress rate also increased in the presence of all surfactants. Surfactant-incorporation affected both the kinetic and thermodynamics factors governing phase separation of RTV-PVPVA-water system, modifying the phase morphology during ASD dissolution. Importantly, SDS increased the miscibility of RTV-PVPVA-water system, whereas other surfactants mainly affected the phase separation kinetics/drug-rich barrier persistence.

CONCLUSION

Incorporation of surfactants enhanced drug release from RTV-PVPVA ASDs compared to the binary system. Increased drug-polymer-water miscibility and disruption of the drug-rich barrier at the gel-solvent interface via plasticization are highlighted as two key mechanisms underlying surfactant impacts based on direct visualization of the phase separation process upon hydration and release.

Utilizing Drug Amorphous Solid Dispersions for the Preparation of Dronedarone per os Formulations

Dronedarone (DRN), an antiarrhythmic drug, exhibits potent pharmacological effects in the management of cardiac arrhythmias. Despite its therapeutic potential, DRN faces formulation challenges due to its low aqueous solubility. Hence, the present study is dedicated to the examination of amorphous solid dispersions (ASDs) as a strategic approach for enhancing the solubility of DRN. Initially, the glass forming ability (GFA) of API was assessed alongside its thermal degradation profile, and it was revealed that DRN is a stable glass former (GFA III compound) that remains thermally stable up to approximately 200 °C. Subsequently, five commonly used ASD matrix/carriers, i.e., hydroxypropyl methylcellulose (HPMC), povidone (PVP), copovidone (PVP/VA), Soluplus® (SOL), and Eudragit® E PO (EPO), were screened for the formation of a DRN-based ASD using film casting and solvent shift methods, along with miscibility evaluation measurements. SOL proved to be the most promising matrix/carrier among the others, and, hence, was used to prepare DRN ASDs via the melt-quench method. The physicochemical characterization of the prepared systems (via pXRD) revealed the complete amorphization of the API within the matrix/carrier, while the system was physically stable for at least three months after its preparation. In vitro release studies for the ASDs, conducted under non-sink conditions, revealed the sustained supersaturation of the drug for at least 8 h. Finally, the use of attenuated total reflectance (ATR) FTIR spectroscopy showed the formation of a strong molecular interaction between the drug molecules and SOL.

Impact of Poloxamer on Crystal Nucleation and Growth of Amorphous Clotrimazole

Surfactants have been widely used as effective additives to increase the solubility and dissolution rates of amorphous solid dispersions (ASDs). However, they may also generate adverse effects on the physical stability of ASDs. In this study, we systematically investigated the impacts of poloxamer, a frequently used surfactant, on the crystallization of amorphous clotrimazole (CMZ). The added poloxamer significantly decreased the glass transition temperature (Tg) of CMZ and accelerated the growth of Form 1 and Form 2 crystals. It was found that the poloxamer had an accelerating effect on Form 1 and Form 2 but showed a larger accelerating effect on Form 1, which resulted from a combined effect of increased mobility and local phase separation at the crystal-liquid interface. Additionally, the added poloxamer exhibited different effects on nucleation of the CMZ polymorphs, which was more complicated than crystal growth. The nucleation rate of Form 1 was significantly increased by the added poloxamer, and the effect increased with increasing P407 content. However, for Form 2, nucleation was slightly decreased or unchanged. The nucleation of Form 2 may have been influenced by the Form 1 crystallization, and Form 2 converted to Form 1 during nucleation. This study increases our understanding of poloxamer and its impacts on the melt crystallization of drugs.

Effects of Additives on the Physical Stability and Dissolution of Polymeric Amorphous Solid Dispersions: a Review

Polymeric amorphous solid dispersion (ASD) is a popular approach for enhancing the solubility of poorly water-soluble drugs. However, achieving both physical stability and dissolution performance in an ASD prepared with a single polymer can be challenging. Therefore, a secondary excipient can be added. In this paper, we review three classes of additives that can be added internally to ASDs: (i) a second polymer, to form a ternary drug-polymer-polymer ASD, (ii) counterions, to facilitate in situ salt formation, and (iii) surfactants. In an ASD prepared with a combination of polymers, each polymer exerts a unique function, such as a stabilizer in the solid state and a crystallization inhibitor during dissolution. In situ salt formation in ASD usually leads to substantial increases in the glass transition temperature, contributing to improved physical stability. Surfactants can enhance the wettability of ASD particles, thereby promoting rapid drug release. However, their potential adverse effects on physical stability and dissolution, resulting from enhanced molecular mobility and competitive molecular interaction with the polymer, respectively, warrant careful consideration. Finally, we discuss the impact of magnesium stearate and inorganic salts, excipients added externally upon downstream processing, on the solid-state stability as well as the dissolution of ASD tablets.

Preparation of the Levo-Tetrahydropalmatine Liposome Gel and Its Transdermal Study

Purpose

The aim of this study was to develop a liposome gel containing levo-tetrahydropalmatine (l-THP) and evaluate its transdermal properties.

Methods

A L16 (43) orthogonal experiment was conducted to optimize the preparation of l-THP liposomes and assess their characterization and stability in a gel. The transdermal features were analyzed through in vivo and in vitro experiments on rats and Strat-M® membrane, respectively. The metabolism of l-THP in liver and skin S9 fractions was also studied.

Results

The optimization of the orthogonal experiment revealed that the ideal mass ratio of phosphatidylcholine, cholesterol, and l-THP during preparation was 10:1:3. The resulting liposome exhibited a particle size of 68 nm, a PDI of 0.27, a drug loading of 4.33%, an encapsulation of 18.79%, and a zeta potential of -41.27 mV. Both the l-THP and its liposome-gel formulation were found to be stable for a duration of 45 days at 4 °C and 30 °C. During the in vivo transdermal study, the maximum concentration (Cmax) of l-THP from the liposome gel was 0.16 μg/mL, and the time to reach this maximum concentration (tmax) was 1.2 hours. The relative bioavailability of l-THP in the liposome gel was 233.8% compared to the emulsion. The concentration of l-THP (prepared in PBS) decreased at a rate of 0.0067 μg/mL/min in the liver S9 fraction and 0.0027 μg/mL/min in the skin S9 fraction, however, this difference was not observed when l-THP was encapsulated in liposomes. l-THP passed through the Strat-M® membrane at a rate of 0.0032 mg/cm2/h and 0.002 mg/cm2/h for the emulsion and liposome gel, respectively.

Conclusion

The optimal process for the preparation of l-THP liposomes was obtained. Compared to the emulsion, the liposomes provided greater bioavailability when used transdermally. The liposomes also provided greater stability for l-THP during storage.

Advances in the development of amorphous solid dispersions: The role of polymeric carriers

Amorphous solid dispersion (ASD) is one of the most effective approaches for delivering poorly soluble drugs. In ASDs, polymeric materials serve as the carriers in which the drugs are dispersed at the molecular level. To prepare the solid dispersions, there are many polymers with various physicochemical and thermochemical characteristics available for use in ASD formulations. Polymer selection is of great importance because it influences the stability, solubility and dissolution rates, manufacturing process, and bioavailability of the ASD. This review article provides a comprehensive overview of ASDs from the perspectives of physicochemical characteristics of polymers, formulation designs and preparation methods. Furthermore, considerations of safety and regulatory requirements along with the studies recommended for characterizing and evaluating polymeric carriers are briefly discussed.

Effect of Span 20 Feeding Zone in the Twin Screw Extruder on the Properties of Amorphous Solid Dispersion of Ritonavir

A ternary amorphous solid dispersion (ASD) system consisting of drug/polymer/surfactant is receiving increased attention to improve the oral bioavailability of poorly water-soluble drugs. The effect of polymers has been extensively studied, while the impact of surfactants has not yet to be studied to the same extent. Challenging questions to be answered are whether the surfactants should be added with the drug or separately and the resulting differences between the two operating processes. By adjusting the liquid feeding zone for Span 20 in the hot-melt twin screw extruder equipment, we investigated the effect of Span 20 on the properties of the polyvinylpyrrolidone/vinyl acetate (PVPVA)-based ASD formulations of ritonavir. We found that with the delayed feeding positions of Span 20 in the twin screw extruder, the ability of the ternary ASDs to maintain the supersaturation of the milled extrudates was observed to be significantly enhanced. Furthermore, adding surfactant after a thorough mixing of polymer and drug could decrease the molecular mobility of ternary ASD formulations. In addition, the effects of Span 20 on the complex viscosity and structure of PVPVA were also investigated. The delayed addition of Span 20 could improve the complex viscosity of PVPVA, thus leading to the drug precipitation inhibition. In conclusion, the delayed addition of Span 20 in the twin screw extruder and prolonging the mixing time of the drug and polymer may be critical to the maintenance of supersaturation.

Preparation and Evaluation of Amorphous Solid Dispersions for Enhancing Luteolin's Solubility in Simulated Saliva

Luteolin (LUT), a bioactive flavonoid, possesses various pharmacological properties, including antioxidant, antimicrobial, anti-allergic, cardio-protective, and anti-cancer activity. Among them, LUT's administration for the treatment of periodontal disease is very promising. However, its low water solubility magnifies the challenge of formulating LUT into an effective dosage form. In this vein, the aim of the present study examines the preparation of amorphous solid dispersions (ASD) for the solubility improvement of LUT in saliva. At first, the physicochemical properties of the active pharmaceutical ingredient (API) were studied before the selection of the most suitable ASD matrix/carrier. For this reason, six commonly used polymeric ASD matrix/carriers (namely, povidone, PVP; copovidone, coPVP; hydroxypropyl cellulose, HPC-SL; hydroxypropyl methyl cellulose acetate succinate, HPMC-AS; Eudragit^® RS, Eud-RS; and Soluplus^®, SOL) were screened via the film casting method, as to whether they could suspend the drug's recrystallization. The most promising matrix/carriers were then evaluated, based on their ability to inhibit LUT's precipitation after its solubilization, via the solvent shift method. Based on both screening methods, it was determined that PVP was the most promising matrix/carrier for the preparation of LUT's ASDs. Hence, in a further step, after the successful testing of components' miscibility, LUT-PVP ASDs were prepared via the solvent evaporation method. These systems (examined via powder X-ray diffractometry, pXRD) showed full API amorphization immediately after preparation and excellent physical stability (since they were stable after 3 months of storage). The study of LUT-PVP ASD's ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) spectra demonstrated strong H-bonds between the molecules of the drug and the matrix/carrier, while molecular dynamics (MD) simulations were able to shed light on these drug-matrix/carrier interactions, at a molecular level. Finally, in vitro dissolution studies in simulated saliva proved that the prepared ASDs were able to significantly enhance LUT's dissolution profile. Hence, according to findings of the present work, the preparation of LUT-ASDs utilizing PVP as the polymeric matrix/carrier is regarded as a highly promising technique for the improvement of API's solubility in the oral cavity.

Treatment and novel resource-utilization methods for shale gas oil based drill cuttings - A review

The oil exploration and production (E&P) industry has made outstanding contributions to gross domestic product (GDP) growth in many countries. In recent years, the gap between energy supply and demand has widened, and, simultaneously, demand for clean energy has gradually increased. As an emerging clean energy source, shale gas has received extensive attention. However, the environmental problems caused by oil and gas extraction and production should not be underestimated. Oil-based drill cuttings (OBDC) are typical hazardous solid wastes produced during oil/gas exploration and production processes. In addition, oil-based drill cuttings ash (OBDCA) is the main product of treated OBDC and should be further utilized to avoid pollution and waste of resources. This review describes relevant policies and regulations for the OBDC. The main treatment methods for OBDC have been systematically summarized. Compared to the standard method for resource utilization of OBDCA, a novel approach was proposed to utilize OBDCA as an environment-friendly functional material for environmental remediation. The future development prospects for OBDC were envisioned to achieve sustainable development goals.

Role of surfactants in improving release from higher drug loading amorphous solid dispersions

Amorphous solid dispersion formulations (ASD) are increasingly being used as a formulation strategy to improve bioavailability of poorly soluble drugs. One of the limitations of ASDs, in particular for high glass transition temperature (T_g) compounds, is the drug loading threshold (termed the limit of congruency, LoC) below which rapid, complete and congruent release of drug and polymer is achieved. In this study, several ionic and non-ionic surfactants were added to atazanavir-copovidone ASDs with the main goal of increasing the limit of congruency. Atazanavir (ATZ) is a relatively high T_g compound with a LoC of 5 % drug loading (DL). Surface normalized dissolution studies revealed that addition of 5 % w/w of surfactant, sodium dodecyl sulfate (SDS) or cetrimonium bromide (CTAB), to the binary copovidone-based ASD doubled the LoC (from 5 to 10 % DL), resulting in a more than 30-fold increase in total release compared to the corresponding binary ASD. Moreover, addition of 5 % of Span®80 increased the LoC to 15 % DL. ASD T_g was found to decrease upon addition of surfactants and water sorption extent was found to increase. We speculate that surfactants act as plasticizers, which may facilitate polymer release from ASDs containing a high T_g drug, providing a possible explanation for the observed enhancement in drug release from ternary ASDs and the increase in LoC.

A Comprehensive Review on the Chemical Properties, Plant Sources, Pharmacological Activities, Pharmacokinetic and Toxicological Characteristics of Tetrahydropalmatine

Tetrahydropalmatine (THP), a tetrahydroproberine isoquinoline alkaloid, is widely present in some botanical drugs, such as Stephania epigaea H.S. Lo (Menispermaceae; Radix stephaniae epigaeae), Corydalis yanhusuo (Y.H.Chou & Chun C.Hsu) W.T. Wang ex Z.Y. Su and C.Y. Wu (Papaveraceae; Corydalis rhizoma), and Phellodendron chinense C.K.Schneid (Berberidaceae; Phellodendri chinensis cortex). THP has attracted considerable attention because of its diverse pharmacological activities. In this review, the chemical properties, plant sources, pharmacological activities, pharmacokinetic and toxicological characteristics of THP were systematically summarized for the first time. The results indicated that THP mainly existed in Papaveraceae and Menispermaceae families. Its pharmacological activities include anti-addiction, anti-inflammatory, analgesic, neuroprotective, and antitumor effects. Pharmacokinetic studies showed that THP was inadequately absorbed in the intestine and had rapid clearance and low bioavailability in vivo, as well as self-microemulsifying drug delivery systems, which could increase the absorption level and absorption rate of THP and improve its bioavailability. In addition, THP may have potential cardiac and neurological toxicity, but toxicity studies of THP are limited, especially its long-duration and acute toxicity tests. In summary, THP, as a natural alkaloid, has application prospects and potential development value, which is promising to be a novel drug for the treatment of pain, inflammation, and other related diseases. Further research on its potential target, molecular mechanism, toxicity, and oral utilization should need to be strengthened in the future.

CMC determination using isothermal titration calorimetry for five industrially significant non-ionic surfactants

Surfactants are used in a vast array of products including pharmaceuticals, cosmetics and household formulations. From an industrial perspective, non-ionic surfactants are ideal for inclusion within such products as they are non-toxic, simple to formulate and economic to use. This study considers five non-ionic surfactants (Tween 20, Tween 80, Crodasol, Croduret and Etocas 35) to determine the critical micellar concentration (CMC) for each using isothermal titration calorimetry, thus avoiding issues regarding poor accuracy found with other techniques. Furthermore, this methodology has not previously been applied to this group of surfactants. For the most commonly used non-ionics (Tween 20 and Tween 80) a further study was undertaken to consider the influence of surfactant purity on the CMC determined, using standard grade (Tween 20 and 80), high purity (Tween 20 HP and Tween 80 HP) and Super Refined (SR PS20 and SR PS80). Results permitted calculation of the CMC for the surfactants whereupon the values were determined to range from 1.0 mM for Tween 20 HP to 2.9 mM for Tween 80 HP. Such information regarding the CMC event is useful from a formulation perspective as it can ensure that the most optimum concentration of surfactant is included within a formulation to maximize its efficacy.

Cellulose derivatives as effective recrystallization inhibitor for ternary ritonavir solid dispersions: In vitro-in vivo evaluation

Amorphous solid dispersions (ASDs) are regarded as one of the most promising techniques for poorly-soluble active pharmaceutical ingredients (API). However, the thermodynamic instability of ASDs at supersaturated state makes them easy to recrystallize in aqueous media. In this study, ritonavir (RTV) was selected as a model drug for evaluating the solubility enhancement and recrystallization inhibition effect of various cellulose derivatives and the combinations of them with typical surfactants. Combination of HPMCAS-HF/SLS was filtrated for preparing ternary RTV solid dispersions (RTV SD) via solvent evaporation method. RTV SD exhibited enhanced dissolution manner, while the oral bioavailability of RTV SD was equivalent with the Reference Standard Norvir® but increased significantly compared to the ternary physical mixture. Thus, the ternary SD system might be promisingly employed as efficient drug delivery system for RTV, while the HPMCAS-HF/SLS combination could be recommended as effective excipient for fabricating steady solid dispersions loading poorly soluble API.