Improved bioavailability of a micronized megestrol acetate tablet formulation in humans

A novel megestrol acetate electrochemical sensor based on conducting functionalized acetylene black-CeO2NPs nanohybrids decorated glassy carbon microspheres

For the first time, megestrol acetate (MGA), a synthetic progestin with therapeutic use in breast cancer, is electrochemically studied to propose a new electroanalytical alternative for its detection in real samples. In the present work, a novel electrochemical sensor based on functionalized acetylene black-CeO₂NPs nanohybrids modified glassy carbon microspheres paste electrode (FAB-CeO₂NPs/GCMPE) was successfully fabricated and used for sensitive determination of MGA. The modified electrode has been characterized using scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrocatalytic reduction of MGA using FAB-CeO₂NPs/GCMPE was carried out via CV and square wave voltammetry (SWV). By employing FAB-CeO₂NPs/GCMPE, the SWV signal of MGA reduction was 8 fold higher than the bare GCMPE. A wide concentration range from 4.20 × 10^-8 to 1.13 × 10^-6 M with the low LOD of 1.30 nM for MGA was achieved. The practical analytical utilities of the prospective FAB-CeO₂NPs/GCMPE sensor were demonstrated successfully by the detection of MGA in Megace tablets, human serum and urine samples obtained from healthy and patient volunteers after oral administration of 160 mg Megace tablets. HPLC method was also developed for comparison with the electroanalytical method.

Assessment of spiramycin-loaded chitosan nanoparticles treatment on acute and chronic toxoplasmosis in mice

Toxoplasmosis is a zoonotic parasitic disease with worldwide distribution. Chitosan is a natural polymer which is commonly used in the production of nanomedicines. It is known to enable higher drug permeation, being biocompatible and has very low toxicity, besides its antimicrobial effects. Our study aimed to assess the effect of spiramycin-loaded chitosan nanoparticles (SLCNs) in treatment of acute and chronic toxoplasmosis in mice. 200 male Swiss albino mice were included in our study, divided to two main groups; Toxoplasma gondii RH strain infected group and ME49 strain infected group, each main group was subdivided into four subgroups; subgroup I: infected control, subgroup II: infected and received chitosan nanoparticles (CS NPs); 20 µg of CS NPs in 100 µl of PBS/mouse/dose, subgroup III: infected and treated with spiramycin (Rovamycin); 100 mg/kg/day, subgroup IV: infected and treated with 100 mg/kg/day spiramycin-loaded chitosan nanoparticles. Effect of treatment was assessed parasitologically and histopathologically. It was noticed that SLCNs significantly decreased the mortality rate of infected mice with both strains compared to high mortality rate of mice in the infected control subgroups. Moreover, there was a significant decrease in the number of organisms of SLCNs treated subgroup as compared to the other subgroups. Histopathological studies showed a marked improvement of the pathological pictures of brain, liver, spleen and eye in the subgroup received SLCNs as opposed to other groups. In conclusion, the present study revealed that loading of spiramycin on chitosan nanoparticles increased its antiparasitic effect on acute and chronic T. gondii infection.

Fabrication of Eudragit polymeric nanoparticles using ultrasonic nebulization method for enhanced oral absorption of megestrol acetate

Megestrol acetate (MGA) is used as a progestagen to treat advanced cancers in the breast or uterus and anorexia-cachexia syndrome in cancer patients. Due to its low solubility (BCS class II), MGA bioavailability needs to be enhanced for efficacy and safety. We developed MGA-encapsulated Eudragit^® L100 (EUD) nanoparticles (MGA-EUD (1:1) and MGA-EUD (2:1)) using an ultrasonic nebulization method. MGA-EUD (1:1) and MGA-EUD (2:1) consisted of MGA and EUD at the mass ratios of 1:1 and 2:1. Their physicochemical properties, i.e. particle size, loading efficiency, morphology, and crystallinity were determined. Dissolution tests were performed using USP method II. For pharmacokinetics, they were orally administered at 50 mg/kg to mice. Microcrystalline MGA suspension (MGA-MC, Megace^®, BMS) was used as control. MGA-EUD (1:1) and MGA-EUD (2:1) had a smooth and spherical shape of 0.70 and 1.05 µm in diameter with loading efficiencies of 93 and 95% showing amorphous states of MGA. They significantly enhanced the dissolution potential of MGA. Oral bioavailability of MGA-EUD (1:1) and MGA-EUD (2:1) increased 2.0- and 1.7-fold compared to that of MGA-MC. It suggests that ultrasonic nebulization method for the fabrication of polymeric nanoparticles is a promising approach to improve the bioavailability of poorly soluble drugs.

Effect of surface chemistry on nanoparticle interaction with gastrointestinal mucus and distribution in the gastrointestinal tract following oral and rectal administration in the mouse

It is believed that mucoadhesive surface properties on particles delivered to the gastrointestinal (GI) tract improve oral absorption or local targeting of various difficult-to-deliver drug classes. To test the effect of nanoparticle mucoadhesion on distribution of nanoparticles in the GI tract, we orally and rectally administered nano- and microparticles that we confirmed possessed surfaces that were either strongly mucoadhesive or non-mucoadhesive. We found that mucoadhesive particles (MAP) aggregated in mucus in the center of the GI lumen, far away from the absorptive epithelium, both in healthy mice and in a mouse model of ulcerative colitis (UC). In striking contrast, water absorption by the GI tract rapidly and uniformly transported non-mucoadhesive mucus-penetrating particles (MPP) to epithelial surfaces, including reaching the surfaces between villi in the small intestine. When using high gavage fluid volumes or injection into ligated intestinal loops, common methods for assessing oral drug and nanoparticle absorption, we found that both MAP and MPP became well-distributed throughout the intestine, indicating that the barrier properties of GI mucus were compromised. In the mouse colorectum, MPP penetrated into mucus in the deeply in-folded surfaces to evenly coat the entire epithelial surface. Moreover, in a mouse model of UC, MPP were transported preferentially into the disrupted, ulcerated tissue. Our results suggest that delivering drugs in non-mucoadhesive MPP is likely to provide enhanced particle distribution, and thus drug delivery, in the GI tract, including to ulcerated tissues.

Novel nanocrystal formulation of megestrol acetate has improved bioavailability compared with the conventional micronized formulation in the fasting state

Background

Megestrol acetate is an effective treatment for improving appetite and increasing body weight in patients with cancer-associated anorexia. However, Megace^® oral suspension (OS), a micronized formulation of megestrol acetate, has low bioavailability in the fasting state. To overcome this limitation, a nanocrystal formulation has been developed. This study was performed to evaluate the pharmacokinetics and tolerability of the nanocrystal formulation and to compare them with those of Megace^® OS in the fed and fasting states.

Methods

A randomized, open-label, two-treatment, two-period, two-sequence, crossover study was performed in three parts in 93 healthy subjects. A single 625 mg/5 mL oral dose of a nanocrystal formulation was administered in the fasting and fed states (part I). In parts II and III, a single 625 mg/5 mL oral dose of the nanocrystal formulation or Megace^® OS 800 mg/20 mL was given in the fed and fasting states, respectively. Blood samples were collected for up to 120 hours post dose for pharmacokinetic analysis. Tolerability was evaluated throughout the entire study period.

Results

The nanocrystal formulation of megestrol acetate was rapidly absorbed in both the fed and fasting states. In the fed state, systemic exposure was comparable between the nanocrystal formulation of megestrol acetate and Megace^® OS. In the fasting state, however, the peak plasma concentration and area under the plasma concentration-time curve to the last measurable concentration of megestrol acetate was 6.7-fold and 1.9-fold higher, respectively, for the nanocrystal formulation than for Megace^® OS. No serious adverse events were reported.

Conclusion

Systemic exposure to megestrol acetate is less affected by lack of concomitant food intake when it is administered using the nanocrystal formulation. The nanocrystal formulation of megestrol acetate could be more effective in treating patients with cachexia or anorexia.

Progestogens used in postmenopausal hormone therapy: differences in their pharmacological properties, intracellular actions, and clinical effects

The safety of progestogens as a class has come under increased scrutiny after the publication of data from the Women's Health Initiative trial, particularly with respect to breast cancer and cardiovascular disease risk, despite the fact that only one progestogen, medroxyprogesterone acetate, was used in this study. Inconsistency in nomenclature has also caused confusion between synthetic progestogens, defined here by the term progestin, and natural progesterone. Although all progestogens by definition have progestational activity, they also have a divergent range of other properties that can translate to very different clinical effects. Endometrial protection is the primary reason for prescribing a progestogen concomitantly with postmenopausal estrogen therapy in women with a uterus, but several progestogens are known to have a range of other potentially beneficial effects, for example on the nervous and cardiovascular systems. Because women remain suspicious of the progestogen component of postmenopausal hormone therapy in the light of the Women's Health Initiative trial, practitioners should not ignore the potential benefits to their patients of some progestogens by considering them to be a single pharmacological class. There is a lack of understanding of the differences between progestins and progesterone and between individual progestins differing in their effects on the cardiovascular and nervous systems, the breast, and bone. This review elucidates the differences between the substantial number of individual progestogens employed in postmenopausal hormone therapy, including both progestins and progesterone. We conclude that these differences in chemical structure, metabolism, pharmacokinetics, affinity, potency, and efficacy via steroid receptors, intracellular action, and biological and clinical effects confirm the absence of a class effect of progestogens.

Pluronic block copolymers and Pluronic poly(acrylic acid) microgels in oral delivery of megestrol acetate

Several Pluronic-based formulations were studied in-vitro and in a rat model with respect to the release and bioavailability of megestrol acetate (MA) after oral administration. It was demonstrated that an aqueous, micellar formulation comprising a mixture of a hydrophobic (L61) and a hydrophilic (F127) Pluronic copolymer, significantly enhanced the bioavailability of MA administered orally at relatively low doses (1–7 mg kg−1). Pluronic-based microgels (spherical gel particles of sub-millimetre size) were introduced as MA vehicles. The microgels comprised a cross-linked network of poly(acrylic acid) onto which the Pluronic chains were covalently attached. Microgels of Pluronic L92 and poly(acrylic acid) fabricated into tablet dosage forms exhibited dramatically lowered MA initial burst release. The MA release was pH-dependent owing to the pH sensitivity of the microgel swelling, with the drug retained by the microgel at pH 1.8 and released slowly at pH 6.8. In the rat model, a significant increase in MA bioavailability was observed when the microgel-formulated MA was administered orally at a high dose of 10 mg kg−1, owing to the enhanced retention of the microgel. The study of the microgel passage through the gastrointestinal tract demonstrated the microgel retention characteristic of a very high molecular weight polymer and the absence of any systemic absorption of the polymer.

Increased Dissolution Rate and Bioavailability Through Comicronization with Microcrystalline Cellulose

Micronization is a commonly used enabling technology to improve the bioavailability of compounds where absorption is dissolution rate limited. However, decreasing particle size often results in increased Van der Waals' interactions and electrostatic attraction between particles. This causes agglomeration of particles, thereby compromising the increase in surface area gained by micronization. Comicronization with excipients has been reported to offer significant advantages over neat micronization. The present work describes the comicronization of a model compound CI-1040 at a high drug load that shows an increase in the dissolution rate and bioavailability in male Wistar rats. Physicochemical characterization of the comicronized and neat micronized material is presented to help explain the in-vitro and in-vivo data.

Dissolution improvement and the mechanism of the improvement from cocrystallization of poorly water-soluble compounds

PURPOSE

To demonstrate improvement in the dissolution of exemestane and megestrol acetate from cocrystallization using various particle sizes and to investigate the mechanism of the improved dissolution.

METHODS

Cocrystal screening was performed by slurry crystallization. The cocrystals were identified and characterized by powder X-ray diffraction, thermal analysis, and single crystal X-ray diffraction. Different particle sizes of each cocrystal were prepared from organic solutions. Solubility and dissolution rates were evaluated using dissolution tests. Transformation behavior of the cocrystals in suspension was analyzed by PXRD and polarization microscopy.

RESULTS

Two novel cocrystals were obtained: exemestane (EX)/maleic acid (MAL) (cocrystal 1) and megestrol acetate (MA)/saccharin (SA) (cocrystal 2). Cocrystal 1 showed a high dissolution rate even with large particles. Cocrystal 2 showed supersaturation with fine particles. The transformation from cocrystal 1 to EX was observed within 1 min in suspension. Cocrystal 2 was transformed to MA within 2-4 h.

CONCLUSIONS

Cocrystallizations of EX and MA improved initial dissolution rates compared to the respective original crystals. The mechanism of dissolution enhancement varied. With cocrystal 1, fine particle formation resulted in enhancement, whereas with cocrystal 2, enhancement was due to the maintenance of the cocrystal form and rapid dissolution before transformation to the original crystal.

Physicochemical properties and oral bioavailability of amorphous atorvastatin hemi-calcium using spray-drying and SAS process

The objective of the study was to prepare amorphous atorvastatin hemi-calcium using spray-drying and supercritical antisolvent (SAS) process and evaluate its physicochemical properties and oral bioavailability. Atorvastatin hemi-calcium trihydrate was transformed to anhydrous amorphous form by spray-drying and SAS process. With the SAS process, the mean particle size and the specific surface area of amorphous atorvastatin were drastically changed to 68.7+/-15.8nm, 120.35+/-1.40m2/g and 95.7+/-12.2nm, 79.78+/-0.93m2/g from an acetone solution and a tetrahydrofuran solution, respectively and appeared to be associated with better performance in apparent solubility, dissolution and pharmacokinetic studies, compared with unprocessed crystalline atorvastatin. Oral AUC0-8h values in SD rats for crystalline and amorphous atorvastatin were as follow: 1121.4+/-212.0ngh/mL for crystalline atorvastatin, 3249.5+/-406.4ngh/mL and 3016.1+/-200.3ngh/mL for amorphous atorvastatin from an acetone solution and a tetrahydrofuran solution with SAS process, 2227.8+/-274.5 and 2099.9+/-339.2ngh/mL for amorphous atorvastatin from acetone and tetrahydrofuran with spray-drying. The AUCs of all amorphous atorvastatin significantly increased (P<0.05) compared with crystalline atorvastatin, suggesting that the enhanced bioavailability was attributed to amorphous nature and particle size reduction. In addition, the SAS process exhibits better bioavailability than spray-drying because of particle size reduction with narrow particle size distribution. It was concluded that physicochemical properties and bioavailability of crystalline atorvastatin could be improved by physical modification such as particle size reduction and generation of amorphous state using spray-drying and SAS process. Further, SAS process was a powerful methodology for improving the physicochemical properties and bioavailability of atorvastatin.

Systemic anticancer therapy in gynecological cancer patients with renal dysfunction

Chronic kidney disease is a common occurrence in patients with gynecological cancer. Systemic anticancer treatment in such patients is a challenge for clinicians because of altered drug pharmacokinetics. For those drugs that are excreted mainly by the kidneys, decreased renal function may lead to increased systemic exposure and increased toxicity. Dose adjustment based on pharmacokinetic changes is required in this situation to avoid life-threatening toxicity. In this review, we summarize the nephrotoxicity and pharmacokinetic data of agents commonly used in systemic anticancer treatment of gynecological cancers and dose adjustment guidelines in the presence of impaired renal function. We review 17 medications that need dose adjustment (cisplatin, carboplatin, doxorubicin, epirubicin, cyclophosphamide, ifosfamide, topotecan, irinotecan, etoposide, capecitabine, bleomycin, methotrexate, actinomycin D, granulocyte-macrophage colony-stimulating factor, metoclopramide, cimetidine, and diphenhydramine) as well as 27 drugs that do not (paclitaxel, docetaxel, pegylated liposomal doxorubicin, gemcitabine, oxaliplatin, fluorouracil, vincristine, letrozole, anastrozole, tamoxifen, leuprorelin, megestrol, gefitinib, erlotinib, trastuzumab, leucovorin, granulocyte colony-stimulating factor, erythropoietin, ondansetron, granisetron, palonosetron, tropisetron, dolasetron, aprepitant, dexamethasone, lorazepam, and diazepam). We also review the formulae commonly used to estimate creatinine clearance, including Cockcroft-Gault, Chatelut, Jelliffe, Wright, and the Modification of Diet in Renal Disease study formulae.

The science of megestrol acetate delivery: potential to improve outcomes in cachexia

Cachexia, usually defined as the loss of >5% of an individual's baseline bodyweight over 2-6 months, occurs with a number of diseases that includes not only AIDS and advanced cancer but also chronic heart failure, rheumatoid arthritis, chronic obstructive pulmonary disease, Crohn disease, and renal failure. Anorexia is considered a key component of the anorexia-cachexia syndrome. Progestogens, particularly megestrol acetate, are commonly used to treat anorexia-cachexia. The mechanism of action of megestrol is believed to involve stimulation of appetite by both direct and indirect pathways and antagonism of the metabolic effects of the principal catabolic cytokines. Because the bioavailability of megestrol acetate directly affects its efficacy and safety, the formulation was refined to enhance its pharmacokinetics. Such efforts yielded megestrol acetate in a tablet form, followed by a concentrated oral suspension form, and an oral suspension form developed using nanocrystal technology. Nanocrystal technology was designed specifically to optimize drug delivery and enhance the bioavailability of drugs that have poor solubility in water. Megestrol acetate nanocrystal oral suspension is currently under review by the US FDA for the treatment of cachexia in patients with AIDS. Preclinical pharmacokinetic data suggest that the new megestrol acetate formulation has the potential to significantly shorten the time to clinical response and thus may improve outcomes in patients with anorexia-cachexia.