Some pharmacokinetic indices of oral fluconazole administration to koalas (Phascolarctos cinereus) infected with cryptococcosis

Three asymptomatic koalas serologically positive for cryptococcosis and two symptomatic koalas were treated with 10 mg/kg fluconazole orally, twice daily for at least 2 weeks. The median plasma Cmax and AUC0-8 h for asymptomatic animals were 0.9 μg/mL and 4.9 μg/mL·h, respectively; and for symptomatic animals 3.2 μg/mL and 17.3 μg/mL·h, respectively. An additional symptomatic koala was treated with fluconazole (10 mg/kg twice daily) and a subcutaneous amphotericin B infusion twice weekly. After 2 weeks the fluconazole Cmax was 3.7 μg/mL and the AUC0-8 h was 25.8 μg/mL*h. An additional three koalas were treated with fluconazole 15 mg/kg twice daily for at least 2 weeks, with the same subcutaneous amphotericin protocol co-administered to two of these koalas (Cmax : 5.0 μg/mL; mean AUC0-8 h : 18.1 μg/mL*h). For all koalas, the fluconazole plasma Cmax failed to reach the MIC90 (16 μg/mL) to inhibit C. gattii. Fluconazole administered orally at either 10 or 15 mg/kg twice daily in conjunction with amphotericin is unlikely to attain therapeutic plasma concentrations. Suggestions to improve treatment of systemic cryptococcosis include testing pathogen susceptibility to fluconazole, monitoring plasma fluconazole concentrations, and administration of 20-25 mg/kg fluconazole orally, twice daily, with an amphotericin subcutaneous infusion twice weekly.

In vitro hepatic microsomal metabolism of meloxicam in koalas (Phascolarctos cinereus), brushtail possums (Trichosurus vulpecula), ringtail possums (Pseudocheirus peregrinus), rats (Rattus norvegicus) and dogs (Canis lupus familiaris)

Quantitative and qualitative aspects of in vitro metabolism of the non-steroidal anti-inflammatory drug meloxicam, mediated via hepatic microsomes of specialized foliage (Eucalyptus) eating marsupials (koalas and ringtail possums), a generalized foliage eating marsupial (brushtail possum), rats, and dogs, are described. Using a substrate depletion method, intrinsic hepatic clearance (in vitro Clint) was determined. Significantly, rates of oxidative transformation of meloxicam, likely mediated via cytochromes P450 (CYP), were higher in marsupials compared to rats or dogs. The rank order of apparent in vitro Clint was brushtail possums (n=3) (mean: 394μL/min/mg protein), >koalas (n=6) (50), >ringtail possums (n=2) (36) (with no significant difference between koalas and ringtail possums), >pooled rats (3.2)>pooled dogs (in which the rate of depletion, as calculated by the ratio of the substrate remaining was <20% and too slow to determine). During the depletion of meloxicam, at a first-order rate constant, 5-hydroxymethyl metabolite (M1) was identified in the brushtail possums and the rat as the major metabolite. However, multiple hydroxyl metabolites were observed in the koala (M1, M2, and M3) and the ringtail possum (M1 and M3) indicating that these specialized foliage-eating marsupials have diverse oxidation capacity to metabolize meloxicam. Using a well-stirred model, the apparent in vitro Clint of meloxicam for koalas and the rat was further scaled to compare with published in vivo Cl. The closest in vivo Cl prediction from in vitro data of koalas was demonstrated with scaled hepatic Cl(total) (average fold error=1.9) excluding unbound fractions in the blood and microsome values; whereas for rats, the in-vitro scaled hepatic Cl fu(blood, mic), corrected with unbound fractions in the blood and microsome values, provided the best prediction (fold error=1.86). This study indicates that eutherians such as rats or dogs serve as inadequate models for dosage extrapolation of this drug to marsupials due to differences in hepatic turnover rate. Furthermore, as in vivo Cl is one of the pharmacokinetic indexes for determining therapeutic drug dosages, this study demonstrates the utility of in vitro to in vivo scaling as an alternative prediction method of drug Cl in koalas.

Acupuncture for treatment of arthralgia secondary to aromatase inhibitor therapy in women with early breast cancer: pilot study

BACKGROUND

Aromatase inhibitors (AIs) are recommended as adjuvant hormone treatment for postmenopausal women with early breast cancer. A substantial proportion of women taking AIs experience joint pain and stiffness. Studies have suggested that acupuncture may be effective in treating joint pain.

OBJECTIVE

A pilot study was conducted to evaluate the feasibility, safety and efficacy of using acupuncture to treat AI-induced arthralgia.

METHODS

A total of 32 patients were randomised to receive either sham or real electroacupuncture (EA) twice weekly for 6 weeks. Outcomes of joint pain, stiffness and physical function were measured with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), overall pain severity and interference with the BPI-SF and quality of life (QOL) with the Functional Assessment of Cancer Therapy-General (FACT-G) instrument. Hand strength was assessed by a grip test, and a serum marker of inflammation (C reactive protein (CRP)) was also measured. All assessments were performed at baseline, 6 weeks and 12 weeks, except for blood samples at baseline and 6 weeks only.

RESULTS

No serious adverse events were reported during or after acupuncture treatments. There were no significant differences in outcome measures. However, positive trends were observed in stiffness and physical function at week 12 in favour of real EA.

CONCLUSIONS

Findings suggest that acupuncture is feasible and safe in patients with breast cancer with joint pain caused by AI. A larger study with adequately powered to confirm these results and detect clinically relevant effects is needed.

Twist contributes to hormone resistance in breast cancer by downregulating estrogen receptor-α

The role of estrogen receptor-α (ER) in breast cancer development, and as a primary clinical marker for breast cancer prognosis, has been well documented. In this study, we identified the oncogenic protein, TWIST1 (Twist), which is overexpressed in high-grade breast cancers, as a potential negative regulator of ER expression. Functional characterization of ER regulation by Twist was performed using Twist low (MCF-7, T-47D) and Twist high (Hs 578T, MDA-MB-231, MCF-7/Twist) expressing cell lines. All Twist high expressing cell lines exhibited low ER transcript and protein levels. By chromatin immunoprecipitation and promoter assays, we demonstrated that Twist could directly bind to E-boxes in the ER promoter and significantly downregulate ER promoter activity in vitro. Functionally, Twist overexpression caused estrogen-independent proliferation of breast cells, and promoted hormone resistance to the selective estrogen receptor modulator tamoxifen and selective estrogen receptor down-regulator fulvestrant. Importantly, this effect was reversible on downregulating Twist. In addition, orthotopic tumors generated in mice using MCF-7/Twist cells were resistant to tamoxifen. These tumors had high vascular volume and permeability surface area, as determined by magnetic resonance imaging (MRI). Mechanistically, Twist recruited DNA methyltransferase 3B (DNMT3B) to the ER promoter, leading to a significantly higher degree of ER promoter methylation compared with parental cells. Furthermore, we demonstrated by co-immunoprecipitation that Twist interacted with histone deacetylase 1 (HDAC1) at the ER promoter, causing histone deacetylation and chromatin condensation, further reducing ER transcript levels. Functional re-expression of ER was achieved using the demethylating agent, 5-azacytidine, and the HDAC inhibitor, valproic acid. Finally, an inverse relationship was observed between Twist and ER expression in human breast tumors. In summary, the regulation of ER by Twist could be an underlying mechanism for the loss of ER activity observed in breast tumors, and may contribute to the generation of hormone-resistant, ER-negative breast cancer.