Tanshinone IIA – loaded pellets developed for angina chronotherapy: Deconvolution-based formulation design and optimization, pharmacokinetic and pharmacodynamic evaluation

Development of bicarbonate buffer flow-through cell dissolution test and its application in prediction of in vivo performance of colon targeting tablets

The purpose of this study was to develop a bicarbonate buffer flow-through cell (FTC) dissolution test. Mesalazine colon targeting tablets of a generic development product (test formulation, TF; Mesalazine 400 mg tablet) and the original product (reference formulation, RF; Asacol® 400 mg tablet) were used as model formulations. A clinical bioequivalence (BE) study was conducted on 48 healthy male subjects under fasting conditions. The oral absorption time profiles were calculated by point-area deconvolution. The compendial paddle and FTC apparatus were used for dissolution tests. Bicarbonate or phosphate-citrate buffer solutions (McIlvaine buffer) were used as the dissolution media. A floating lid was used to maintain the pH value of the bicarbonate buffer solution in the vessel (paddle) or the reservoir (FTC). In the development of bicarbonate FTC method, the pH changes of bicarbonate buffer solution (pH 5.5-7.5; 5-50 mM bicarbonate) were evaluated. For the evaluation of colon targeting tablets, the dissolution profiles of TF and RF were measured at a pH of 7.5. The TF and RF formulations were exposed to 0.01 HCl (pH 2.0) for 2 h before pH 7.5. In the clinical BE study, drug dissolution started 4-8 h after oral administration and continued slowly more than 10 h. Both the area under the curve (AUC) and maximum plasma concentration (Cmax) of TF were approximately twice as high as those of RF. In the development of the bicarbonate FTC method, the pH change of the bicarbonate buffer solution was suppressed by the floating lid within ∆pH < 0.1 over 10 h. In the dissolution test of McIlvaine buffer solutions, TF and RF showed faster disintegration and higher dissolution than those observed in the clinical BE study. When using the paddle apparatus the dissolution profiles of TF and RF in both buffer solutions were not consistent with those of the clinical result. In bicarbonate FTC, the disintegration time, dissolution rate, and dissolution inequivalence between TF and RF were consistent with the results of the clinical BE study. In conclusion, the bicarbonate FTC method was constructed for the first time in this study. This method is simple and practically useful for predicting in vivo performance of colon targeting tablets during drug development.

Influence of release rate, dose and co-administration on pharmacokinetics, pharmacodynamics and PK-PD relationship of tanshinone IIA and tanshinol

The present study aims to investigate the influence of release rate, dose and co-administration on pharmacokinetics (PK) and pharmacodynamics (PD) of tanshinone IIA (TA) and tanshinol (TS), and reveal the changes in their PK-PD relationships. Sustained and immediate release pellets of TS and TA were prepared respectively, and oral administrated to angina model rabbits according to the experimental design. The administration dose of TS was 50, 35 or 20 mg/kg and that of TA was 30 mg/kg. Then, plasma concentrations of TS and TA were measured to evaluate the pharmacokinetics. Pharmacodynamic biomarkers including cardiac troponin (cTn-I), creatine kinase (CK-MB), superoxide dismutase (SOD) and nitric oxide (NO) were measured to evaluated the effects of cardioprotection, amelioration of oxidative stress and vasorelaxation of TS and TA. Parameters such as maximum plasma concentration (C_max), maximum effect (E_max), time to C_max or E_max (TC_max or TE_max), areas under the plasma concentration or effect curves (AUC_0-∞ or AUEC) and pharmacodynamic efficiency (EFF) were calculated based on non-compartmental analysis. Beside, PK-PD relationship/hysteresis was evaluated. The TE_max was less sensitive than TC_max to changes in release rate. The E_max, AUEC and EFF showed increasing trend as the decrease of release rate even that the AUC_0-∞ showed no significant difference. In addition, slow drug release decreased the magnitude of hysteresis of TS and TA. The sensitivities of E_max and AUEC of four biomarkers to changes in dose were varied and relatively lower than those of C_max and AUC_0-∞. The EFF decreased and the magnitude of hysteresis increased for high dose. The C_max and AUC_0-∞ of TS and TA showed little difference after co-administration. The E_max and AUEC of four biomarkers increased for immediate release pellets (P < 0.05 or P < 0.01) and generally decreased for sustained release pellets (P < 0.05 or P < 0.01) after co-administration. In addition, the magnitudes of hysteresis of four biomarkers decreased for immediate release pellets and generally increased for sustained release pellets after co-administration. In summary, the dissociated and unstable PK-PD relationship should be considered during optimization of dosage forms and regimens to make sure the rationality, safety and efficacy. These findings could also provide some valuable information for the development and clinical therapy of other drugs.

Design, synthesis and biological evaluation of tanshinone IIA-based analogues: Potent inhibitors of microtubule formation and angiogenesis

We report the structural optimization of tanshinone IIA, a natural product which possesses anti-tumor properties but low water-solubility, weak antiproliferative activity and poor PK properties. A new series of ring A/C/D modified tanshinone analogues were synthesized and studied for their antiproliferative capacities against six human cancer cell lines. SAR study revealed that ring A cleavage of tanshinone IIA led to improved anti-cancer activity. Introduction of a methoxy group to the phenyl ring could enhance the anti-cancer activity even further. Compound 2f with methoxy group at C-8 position was selected as an early lead with IC₅₀ values of 0.28-3.16 μM against six tested cell lines. 2f could bind to tubulin colchicine site, inhibit tubulin assembly and disrupt the normal formation of microtubule networks. Cellular mechanistic studies revealed that 2f induced apoptotic cell death of A549 cells in a dose-dependent manner. In vitro investigations showed that 2f impeded the tubule-formation of HUVECs and potently inhibited the proliferation, migration and invasion of A549 cells as well as HUVECs. Furthermore, the in vivo anti-angiogenic effect of 2f was confirmed via a zebrafish model test. The satisfactory physicochemical property and metabolic stability of 2f, as well as improved water-solubility, further suggested that 2f could serve as a promising tubulin inhibitor and anti-angiogenic agent.

Research progress on nanotechnology for delivery of active ingredients from traditional Chinese medicines

There is growing acceptance of traditional Chinese medicines (TCMs) as potential sources of clinical agents based on the demonstrated efficacies of numerous bioactive compounds first identified in TCM extracts, such as paclitaxel, camptothecin, and artemisinin. However, there are several challenges to achieving the full clinical potential of many TCMs, particularly the generally high hydrophobicity and low bioavailability. Recently, however, numerous studies have attempted to circumvent the limited in vivo activity and systemic toxicity of TCM ingredients by incorporation into nanoparticle-based delivery systems. Many of these formulations demonstrate improved bioavailability, enhanced tissue targeting, and greater in vivo stability compared to the native compound. This review summarizes nanoformulations of the most promising and extensively studied TCM compounds to provide a reference for further research. Combining these natural compounds with nanotechnology-based delivery systems may further improve the clinical utility of these agents, in turn leading to more intensive research on traditional medicinal compounds.

Challenges and strategies in progress of drug delivery system for traditional Chinese medicine Salviae Miltiorrhizae Radix et Rhizoma (Danshen)

Traditional Chinese medicines (TCMs), with a history of thousands of years, are widely used clinically with effective treatment. However, the drug delivery systems (DDSs) for TCMs remains major challenges due to the characteristics of multi-components including alkaloids, flavones, anthraquinones, glycosides, proteins, volatile oils and other types. Therefore, the novel preparations and technology of modern pharmaceutics is introduced to improve TCM therapeutic effects due to instability and low bioavailability of active ingredients. Salviae Miltiorrhizae Radix et Rhizoma, the radix and rhizomes of Salvia miltiorrhiza Bunge (Danshen in Chinese), is a well known Chinese herbal medicine for protecting the cardiovascular system, with active ingredients mainly including lipophilic tanshinones and hydrophilic salvianolic acids. In this review, this drug is taken as an example to present challenges and strategies in progress of DDSs for TCMs. This review would also summary the characteristics of active ingredients in it including physicochemical properties and pharmacological effects. The purpose of this review is to provide inspirations and ideas for the DDSs designed from TCMs by summarizing the advances on DDSs for both single- and multi-component from Danshen.

Preparation of water-soluble chitosan/poly-gama-glutamic acid-tanshinone IIA encapsulation composite and its in vitro/in vivo drug release properties

Some diseases could be treated by Tanshinone IIA (TA), which is an isolated component from the Chinese medicinal herb Tanshen (Salvia miltiorrhiza). However, the poor water solubility and low oral bioavailability of TA limited its clinical application. In this paper, TA was encapsulated by water - soluble chitosan/poly - γ - glutamic acid (WCS-γ-PGA) to improve its dissolution and oral bioavailability. The in vitro dissolution and in vivo metabolism of the encapsulated composite in rats were employed to evaluate the efficiency of the improvement. FTIR spectroscopy was applied to confirm the validity of encapsulation for TA by WCS-γ-PGA. The study's results showed that the optimal ratio of TA to drug carrier (WCS + γ-PGA) was 1:5.5 in weight with a reaction time of 1 h at room temperature for the encapsulation. The proper concentrations for WCS and TA in preparing the encapsulated composite using γ-PGA 0.125 mg ml^-1 were 6 mg ml^-1 and 1 mg ml^-1, respectively; The encapsulation efficiency and drug loading efficiency of WCS-γ-PGA-TA composite were (93.99 ± 2.20)% and (10.73 ± 0.75)%, respectively. The cumulative release of TA from the WCS-γ-PGA-TA encapsulated composite reached to 81% within 60 min, which was 5.56 times of that of the original TA in vitro dissolution. The peak concentration C_max of TA from the encapsulated composite in rat blood as measured by an ultracentrifugation test of an intra - gastric administration was 4.43 times that of the original TA concentration, and the area under the drug-time curve AUC _(0-t) and AUC _(0-∞) (p<0.01) of the WCS-γ-PGA-TA encapsulated composite were 4.56 and 4.20 times that of the original TA, respectively. It indicated that the encapsulation of TA with WCS-γ-PGA improved its solubility and bioavailability significantly.

Development of sustained-release pellets to modulate the in vivo processes of the main active components of Danshen: A pharmacokinetic and pharmacodynamic evaluation

BACKGROUND

Danshen is a first-line traditional Chinese medicine derived from Salvia miltiorrhiza Bunge consisting mainly of tanshinone IIA, tanshinol, protocatechuic aldehyde, and salvianolic acid B, it is widely used to treat cardiovascular diseases based on the synergistic effect of its multiple active components. Recent studies have indicated that the overall effect of traditional Chinese medicine is closely related to the in vivo coexistence of a variety of active components.

HYPOTHESIS

The prolongation of the coexistence of the four active components in Danshen in vivo by regulating their pharmacokinetic processes may contribute to better efficiency.

METHODS/STUDY DESIGNS

Individual sustained-release pellets of the four main active components in Danshen were respectively prepared according to the optimised formulations developed in our previous studies to modulate their in vivo processes, in which the desired release profiles of each kind of sustained-release pellets for formulation optimisation were calculated based on the point-area deconvolution and circadian rhythm of variant angina. The four kinds of sustained-release pellets were filled into capsules on the basis of the original weight ratio of the four active components in purified Salvia miltiorrhiza extract for further in vitro release and pharmacokinetic and pharmacodynamic investigations.

RESULTS

The release behaviours of the combined Danshen capsules composed of the four kinds of sustained-release pellets were evaluated in three media with different pH levels (pH 1.2, 6.8, and pure water). The release profiles of each kind of sustained-release pellets in pH 6.8 PBS and pH 1.2 HCl were similar to the release profile of those in pure water (similarity factors f₂ > 50). Pharmacokinetic studies revealed that the four kinds of sustained-release pellets in the combined Danshen capsules possessed the same T_max and similar and extended MRT. Moreover, pharmacodynamic studies indicated that the combined Danshen capsules had much better anti-angina effects than commercial Danshen capsules according to comprehensive evaluations via electrocardiogram, serum index (CK-MB, cTn-I, ET, and NO), myocardial oxidative damage, and myocardial pathologic biopsy.

CONCLUSION

Sustained-release preparations can markedly prolong the in vivo coexistence of multiple components in Danshen to enhance their overall effects, which provides a potent strategy for developing the combination therapy of traditional Chinese medicine.

Preparation, Characterization and Pharmacokinetics Evaluation of the Compound Capsules of Ibuprofen Enteric-Coated Sustained-Release Pellets and Codeine Phosphate Immediate-Release Pellets

The objective of this study was to prepare ibuprofen enteric-coated sustained-release pellets (IB-SRPs) and codeine phosphate immediate-release pellets (CP-IRPs) to play a synergistic role in analgesia. The pellets were developed by extrusion-spheronization and fluidized bed coating technology. The single-factor investigation was used to determine the optimal prescription and process. The sustained-release membrane of IB-SRPs was water-insoluble ethyl cellulose (EC), triethyl citrate (TEC) was used as plasticizer, and hydroxypropyl methylcellulose (HPMCP) was chose as porogen. Besides, the immediate-release layer of CP-IRPs was gastric-soluble coating film. The ibuprofen and codeine phosphate compound capsules (IB-CP SRCs) were prepared by IB-SRPs and CP-IRPs packed together in capsules with the optimum doses of 200 and 13 mg, respectively. The prepared pellets were evaluated by scanning electron microscopy and dissolution test. Pharmacokinetic studies in beagle dogs indicated that the optimized IB-CP SRCs had smaller individual differences and better reproducibility comparing with commercial available tablets. Additionally, IB-CP SRCs achieved consistency with in vivo and in vitro tests. Therefore, IB-CP SRCs could play a great role in rapid and long-term analgesic.

Tanshinones and mental diseases: from chemistry to medicine

The prevalence of mental diseases, especially neurodegenerative disorders, is ever-increasing, while treatment options for such disorders are limited and insufficient. In this scarcity of available medication, it is a feasible strategy to search for potential drugs among natural compounds, such as those found in plants. One such plant source is the root of Chinese sage, Salvia miltiorrhiza Bunge (Labiatae), which contains several compounds reported to possess neuroprotective activities. The most important of these compounds are tanshinones, which have been reported to possess ameliorative activity against a myriad of mental diseases such as Alzheimer’s disease, cerebral ischemia/reperfusion injury, and glioma, along with promoting neuronal differentiation and manifesting antinociceptive and anticonvulsant outcomes. This review offers a critical evaluation of the utility of tanshinones to treat mental illnesses, and sheds light on the underlying mechanisms through which these naturally occurring compounds confer neuroprotection.

Application of ethyl cellulose, microcrystalline cellulose and octadecanol for wax based floating solid dispersion pellets

The present study aimed to develop and optimize the wax based floating sustained-release dispersion pellets for a weakly acidic hydrophilic drug protocatechuic acid to achieve prolonged gastric residence time and improved bioavailability. This low-density drug delivery system consisted of octadecanol/microcrystalline cellulose mixture matrix pellet cores prepared by extrusion-spheronization technique, coated with drug/ethyl cellulose 100cp solid dispersion using single-step fluid-bed coating method. The formulation-optimized pellets could maintain excellent floating state without lag time and sustain the drug release efficiently for 12h based on non-Fickian transport mechanism. Observed by SEM, the optimized pellet was the dispersion-layered spherical structure containing a compact inner core. DSC, XRD and FTIR analysis revealed drug was uniformly dispersed in the amorphous molecule form and had no significant physicochemical interactions with the polymer dispersion carrier. The stability study of the resultant pellets further proved the rationality and integrity of the developed formulation.