Unusual serum lipoprotein abnormality induced by the vehicle of miconazole

Pharmacological effects of formulation vehicles : implications for cancer chemotherapy

The non-ionic surfactants Cremophor EL (CrEL; polyoxyethyleneglycerol triricinoleate 35) and polysorbate 80 (Tween) 80; polyoxyethylene-sorbitan-20-monooleate) are widely used as drug formulation vehicles, including for the taxane anticancer agents paclitaxel and docetaxel. A wealth of recent experimental data has indicated that both solubilisers are biologically and pharmacologically active compounds, and their use as drug formulation vehicles has been implicated in clinically important adverse effects, including acute hypersensitivity reactions and peripheral neuropathy.CrEL and Tween 80 have also been demonstrated to influence the disposition of solubilised drugs that are administered intravenously. The overall resulting effect is a highly increased systemic drug exposure and a simultaneously decreased clearance, leading to alteration in the pharmacodynamic characteristics of the solubilised drug. Kinetic experiments revealed that this effect is primarily caused by reduced cellular uptake of the drug from large spherical micellar-like structures with a highly hydrophobic interior, which act as the principal carrier of circulating drug. Within the central blood compartment, this results in a profound alteration of drug accumulation in erythrocytes, thereby reducing the free drug fraction available for cellular partitioning and influencing drug distribution as well as elimination routes. The existence of CrEL and Tween 80 in blood as large polar micelles has also raised additional complexities in the case of combination chemotherapy regimens with taxanes, such that the disposition of several coadministered drugs, including anthracyclines and epipodophyllotoxins, is significantly altered. In contrast to the enhancing effects of Tween 80, addition of CrEL to the formulation of oral drug preparations seems to result in significantly diminished drug uptake and reduced circulating concentrations. The drawbacks presented by the presence of CrEL or Tween 80 in drug formulations have instigated extensive research to develop alternative delivery forms. Currently, several strategies are in progress to develop Tween 80- and CrEL-free formulations of docetaxel and paclitaxel, which are based on pharmaceutical (e.g. albumin nanoparticles, emulsions and liposomes), chemical (e.g. polyglutamates, analogues and prodrugs), or biological (e.g. oral drug administration) strategies. These continued investigations should eventually lead to more rational and selective chemotherapeutic treatment.

New homogeneous HDL-cholesterol assay without the influence of high TG sample using the selective detergent to lipoproteins

Homogeneous HDL-cholesterol assays have been developed and used widely in routine analysis, but they have been reported to give inaccurate results in patients with hypertriglyceridemia. Recently, a new assay based on a new principle without the influence of triglycerides has also been developed and commercialized. We evaluated the basic performance of this new homogeneous HDL-cholesterol assay and compared it with the conventional polyethylene glycol/cyclodextrin-modified enzyme (PEGME) method using high-triglyceride (TG) samples (TG>8000 mg/L). For samples showing a discrepancy with the conventional method, other precipitation and ultracentrifugation (UC) methods were also used to confirm the values. This new homogeneous assay is based on the selective solubilizing effect of detergent on the different lipoproteins. First, non-HDL free cholesterol is consumed by enzyme and is cleared as a colorless reactant. Then. HDL-cholesterol is selectively solubilized by lipoprotein-specific detergent and reacted with the enzyme. As a result, the precision of this new homogeneous assay was good (CV<2%) over the wide range, and the measurement range was 0 to 2000 mg/L. This method correlated well with the PEGME method, which is a conventional method for normolipidemic samples (y=0.97x-3.1, r=0.994, n=424). It also correlated well with the UC method (y=0.99x+0.3, r=0.989, n=53). Fourteen high-TG samples showed different results from those obtained by the PEGME method. Among these samples, one contained abnormal lipoproteins (probably due to the influence of drug therapy) and gave a significantly different result from that obtained by the PEGME method. However, the values obtained by other methods (precipitation and ultracentrifugation) agreed well with those obtained by this new method. In conclusion, this method shows a good basic performance and is useful for high-TG samples without any interference. Therefore, it is considered to be very practical for a routine test.

Cremophor EL: the drawbacks and advantages of vehicle selection for drug formulation

Cremophor EL (CrEL) is a formulation vehicle used for various poorly-water soluble drugs, including the anticancer agent paclitaxel (Taxol). In contrast to earlier reports, CrEL is not an inert vehicle, but exerts a range of biological effects, some of which have important clinical implications. Its use has been associated with severe anaphylactoid hypersensitivity reactions, hyperlipidaemia, abnormal lipoprotein patterns, aggregation of erythrocytes and peripheral neuropathy. The pharmacokinetic behaviour of CrEL is dose-independent, although its clearance is highly influenced by duration of the infusion. This is particularly important since CrEL can affect the disposition of various drugs by changing the unbound drug concentration through micellar encapsulation. In addition, it has been shown that CrEL, as an integral component of paclitaxel chemotherapy, modifies the toxicity profile of certain anticancer agents given concomitantly, by mechanisms other than kinetic interference. A clear understanding of the biological and pharmacological role of CrEL is essential to help oncologists avoid side-effects associated with the use of paclitaxel or other agents using this vehicle. With the present development of various new anticancer agents, it is recommended that alternative formulation approaches should be pursued to allow a better control of the toxicity of the treatment and the pharmacological interactions related to the use of CrEL.

Preparation, characterization, and evaluation of miconazole-cyclodextrin complexes for improved oral and topical delivery

The solubility of miconazole in water increased in the presence of cyclodextrins (CDs). The apparent K1:1 values calculated from the phase solubility diagrams of gamma-CD, hydroxypropyl-beta-CD, alpha-CD, hydroxyethyl-beta-CD, hydroxypropyl-gamma-CD, and beta-CD were 695 +/- 39.6, 363 +/- 34.1, 333 +/- 18.5, 312 +/- 31.0, 305 +/- 27.6, and 293 +/- 17.6 M(-1), respectively. Solid 1:1 molar complexes were prepared by freeze-drying and kneading and characterized by UV spectroscopy, differential scanning calorimetry, and electron microscopy. The dissolution rate increased to 28-255-fold and the solubility to 9-55-fold. Oral bioavailability in rats increased to 2.3-fold by complexation with hydroxypropyl-beta-CD. Human cadaver skin retained 2.6-fold more drug from the miconazole/alpha-CD complex and hairless mice skin retained 8.4-fold more drug from the HP-beta-CD complex than from miconazole solution alone in 24 h.

Human plasma distribution of free paclitaxel and paclitaxel associated with diblock copolymers

Amphiphilic diblock copolymer poly (D,L-lactide)-block-methoxy polyethylene glycol was synthesized, and paclitaxel (Taxol) was incorporated into this copolymer above its critical micelle concentration (cmc), resulting in the formation of polymeric micellar paclitaxel (PMT). Free paclitaxel dissolved in acetonitrile (TAX) and PMT, at 10 micrograms of paclitaxel/mL of human plasma, were incubated for 5, 30, and 60 min at 37 degrees C. Following incubation, the plasma was separated into its high-density (HDL), low-density (LDL), very-low-density (VLDL) lipoprotein and lipoprotein-deficient (LPDP) plasma fractions by density gradient ultracentrifugation. Each of these lipoprotein (LP) and LPDP fractions were analyzed for paclitaxel and plasma lipid levels by well-established HPLC and enzymatic assays. When TAX was incubated in human plasma for 5 min, an equal amount of drug was found in the LP and LPDP fractions. This distribution profile did not change following incubation for 30 and 60 min. Of the amount of TAX that was distributed within the LP fraction, 70-75% of TAX was associated with the HDL fraction for all time points studied. The paclitaxel plasma and LP distribution profile for PMT was similar to the distribution profile of TAX, suggesting that the plasma and LP distribution of paclitaxel is independent of the method of paclitaxel delivery and that LP distribution is not a function of mass lipid levels.

PEG-coated poly(lactic acid) nanoparticles for the delivery of hexadecafluoro zinc phthalocyanine to EMT-6 mouse mammary tumours

Hexadecafluoro zinc phthalocyanine (ZnPcF16), a second generation sensitizer for the photodynamic therapy of cancer, was incorporated in three vehicles: poly(D,L-lactic acid) (PLA) nanoparticles, polyethylene glycol (PEG)-coated nanoparticles and a Cremophor EL (CRM) oil-water emulsion. Nanoparticles were prepared by the salting-out procedure. Biodistribution of the dye was assessed by fluorescence in EMT-6 mammary tumour bearing mice after intravenous injection of 1 mumol kg-1 ZnPcF16. Plain nanoparticles were rapidly retained by the reticuloendothelial system (RES) as reflected by the low area under the blood concentration-time curve (AUC0-168, 57 micrograms h g-1). Little tumour uptake of the dye was observed with this formulation. In contrast, PEG-coated nanoparticles displayed a reduced RES uptake, leading to significantly higher blood levels over an extended period (t1/2 30 h; AUC 0-168 227 micrograms h g-1) and enhanced tumour uptake. At 48 h post injection, tumour to skin and tumour to muscle concentration ratios reached 3.5 and 10.8, respectively. Blood levels of ZnPcF16 after administration as a CRM emulsion decreased faster than with PEG-coated nanoparticles (t1/2 12 h), but since no early liver uptake was observed, the AUC0-168 and the tumour uptake were only slightly lower. However, with the CRM formulation, a late liver uptake was observed, reaching 51% of the injected dose after 7 days.

Effects of Cremophor EL on distribution of Taxol to serum lipoproteins

The clinical formulation of the anti-tumour agent Taxol involves the use of a mixture of ethanol and Cremophor EL. Gel electrophoresis and density-gradient ultracentrifugation were used to detect effects of Taxol infusions on serum lipoproteins. Use of the Cremophor vehicle results in a decrease in the electrophoretic mobility of serum lipoproteins along with the appearance of a lipoprotein dissociation product. These effects persist during a 24 h infusion and for at least 1.5 h afterwards, and can be reproduced in vitro using purified high-density lipoprotein (HDL) or low-density lipoprotein (LDL). In control serum, Taxol binds to albumin > HDL, but after serum is exposed to Cremophor EL in vitro or in vivo substantial binding of Taxol to the lipoprotein dissociation product(s) was observed. The latter could represent an important factor in taxol biodistribution.

The alteration of plasma lipoproteins by cremophor EL

Cremophor EL (CRM) is a non-ionic amphipathic emulsifier which has been used as a parenteral vehicle for many hydrophobic drugs. At concentrations above 0.4 mg ml-1, CRM alters lipoproteins so as to reduce their electrophoretic mobility; high density lipoprotein (HDL) is somewhat more sensitive than low density lipoprotein (LDL) in this regard. The same phenomenon was observed with Triton X-100 and Tween-80, two other non-ionic detergents. Ultracentrifugation experiments show that CRM alters the density of HDL resulting in a product with approximately the same specific gravity as LDL. Administration of mesoporphyrin solubilized with CRM to the mouse resulted in a rapid clearance of porphyrin bound to this new HDL species. Such a phenomenon may account for reports which indicate that CRM promotes the distribution of photosensitizing agents to neoplastic tissues.

Biodistribution of O6-benzylguanine and its effectiveness against human brain tumor xenografts when given in polyethylene glycol or cremophor-EL

O6-Benzylguanine effectively inactivates the DNA-repair protein O6-alkylguanine-DNA alkyltransferase in tumor cells and has been shown to increase the cytotoxicity of chloroethylnitrosoureas. This study was undertaken to ascertain the optimal vehicle for further toxicological evaluation and eventual clinical trials of O6-benzylguanine. The solubility, metabolism, bioavailability and effectiveness of O6-benzylguanine as an adjuvant therapy with BCNU were compared using two vehicles, cremophor-EL and PEG 400. Nude mice bearing s.c. D456 MG glioblastoma xenografts were injected i.p. with 10-30 mg/kg O6-benzylguanine dissolved in either 40% PEG 400/saline or 10% cremophor-EL/saline. The number of tumor regressions noted after treatment with 10 mg/kg O6-benzylguanine followed by 12.7 mg/kg BCNU were 8/9 for the drug dissolved in PEG and 1/10 for the drug given in cremophor-EL. Using the same treatment regimen but increasing the dose of O6-benzylguanine to 30 mg/kg led to a growth delay of 45.2 and 11.5 days for the drug dissolved in PEG 400 and cremophor-EL, respectively, although the number of regressions observed were the same for both treatments. 8-[3H]-O6-Benzylguanine was more rapidly distributed to the tumor when it was delivered in PEG vehicle than when it was given in cremophor-EL. In contrast, there was a 3-fold greater amount of O6-benzylguanine in the small intestine of mice at 1 h after i.p. injection of the drug in cremophor-EL as compared with PEG 400. The rate and extent of metabolism in the liver was the same, whether the parent drug was given in PEG 400 or in cremophor-EL. These studies demonstrate that O6-benzylguanine is a more effective enhancer of the antitumor activity of BCNU when it is given in PEG 400 than when it is delivered in cremophor-EL, which may be due to a more rapid distribution of the drug to the tumor.

Fungal endophthalmitis in narcotic abusers. Medical and surgical therapy in 10 patients

The presentation and management of 10 cases of proven or presumptive fungal endophthalmitis in narcotic-drug abusers is described. Miconazole was found to be an effective agent in some patients when administered in a dosage of 2400 mg/day. Eight patients received treatment with a combination of miconazole and flucytosine (5-fluorocytosine). Regression of the infection with preservation of the eye was observed in each case. However, visual acuity in the affected eye improved only in four of the eight patients; it was unchanged in two and had deteriorated in the other two. In two patients, who received amphotericin B and flucytosine as initial treatment, control of the infection was achieved, but vision remained unchanged. Vitrectomy was performed in three patients to remove residual sites of infection. However, vision remained unchanged in two of these patients and worsened in the third. The selection of individual modalities of therapy and responses to treatment are discussed.

Petriellidium (Allescheria) boydii orbital and brain abscess treated with intravenous miconazole

A previously healthy 4-year-old boy suffered a penetrating injury to his left orbit and left frontal lobe, which resulted in an infection by Petriellidium boydii. The patient was successfully treated with intravenous miconazole and multiple debridements.

Effect of long-term continuous infusion of alfathesin on clinical biochemical and haematological parameters

Clinical biochemical and haematological parameters during long-term continuous infusion of alfathesin were studied in twelve neurosurgical patients who did not have multiple organ failure. Significant changes which were possibly caused by alfathesin were an alteration of blood film morphology, an elevation of plasma triglyceride and a reduction in plasma high-density lipids.

Clinical trial of continuous infusion of alphaxalone/alphadolone in intensive care patients

The safety and efficacy of prolonged infusion of alphaxalone/alphadolone (Alfathesin: Glaxo) was assessed in 20 critically ill patients needing sedation during intermittent positive pressure ventilation in a general intensive care unit. The mean dose of Alfathesin infused was 1542 ml (range: 225 to 4820 ml) over 6.9 days (3 to 16 days) at rates between 5 and 15 ml/hour. Significant increases in plasma urea, creatinine, bilirubin, alkaline phosphatase and white cell count occurred during the infusion, but these were expected from each patient's clinical course. Lipoprotein electrophoresis invariably showed loss of the alpha band and appearance of a densely staining pre-beta band. Four patients had involuntary movements during the infusion and two patients fitted when the infusion stopped. Both had cerebral injuries. Subjective assessment of the quality of sedation was "very good" or "good" in 15 patients and "fair" in five.

Antifungal chemotherapy

When the decision to treat a fungal infection is made, there are several antifungal agents available for use. AmB remains the first-line drug in the treatment of most systemic fungal infections. Miconazole should be used to treat patients who cannot tolerate AmB or who are infected with AmB-resistant organisms. Ketoconazole has a distinct advantage in that it is a relatively nontoxic oral agent and may prove very effective in treating non-life-threatening chronic fungal infections. Clinical experience with miconazole and ketoconazole is too limited at present to recommend them as first-line therapeutic agents, except in a limited number of clinical situations. 5-FC should only be used in combination with AmB to treat yeast infections.

Pharmacokinetics of ketoconazole in patients with neoplastic diseases

Twenty-seven patients with advanced malignancies were given 200 mg of ketoconazole orally every 6 or 12 h. Blood samples were collected during these intervals and after the last dose to determine plasma concentrations and half-lives. The mean plasma concentrations measured after the initial dose were 1.7 +/- 1.1 microgram/ml at 2 h, 0.9 +/- 0.2 microgram/ml at 6 h, and 0.7 +/- 0.4 microgram/ml at 8 h. Plasma concentrations rose significantly in patients on the every-6-h schedule. Concentrations were more variable in patients on the every-12-h schedule, and changes in mean plasma concentrations after 7 and 14 days were not significant. Half-lives ranged from 1.3 to 11.6 h in individual patients. The mean half-life for all patients studied was 3.7 +/- 0.6 h on day 1. The calculated area under the curve was 12.0 +/- 4.7 micrograms-h/ml on day 1; it increased after 7 and 14 days of administration (every-6-h schedule), suggesting plasma binding or wide drug distribution or both. Saturation of storage compartments is also suggested. Less than 1% of the administered dose was recoverable as active drug from the urine over 6 h.

Treatment of fungal infections of the central nervous system

The recent development of new antifungal antimicrobials that can be administered in combination with amphotericin B or as alternatives to it has expanded the dimensions of treatment for fungal infections of the central nervous system. These disorders have acquired increasing importance as patients with malignant and other illnesses associated with immunosuppression survive longer and as renal transplantation is more widely applied. Amphotericin B has remained the most effective therapeutic preparation for most types of neurological fungal disease, although important roles for 5-fluorocytosine, miconazole, and, more recently, ketoconazole are being recognized.

Successful treatment of systemic cryptococcosis with miconazole

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Miconazole for treatment of disseminated coccidioidomycosis. Unfavorable experience

Miconazole at dosages up to 30 mg/kg/day was given intravenously to seven patients with complicated courses of disseminated coccidioidomycosis. Six had received treatment with amphotericin B previously and five of these patients could be evaluated for the efficacy of the treatment. In three patients the condition failed to respond to therapy, another patient required intratracheal administration of amphotericin B later, and the fifth patient had an equivocal response to treatment. Severe phlebitis, pruritus, nausea, vomiting, hyperlipidemia, and thrombocytosis were frequent side effects. These limited unfavorable results indicate that until controlled studies demonstrate its safety and efficacy, therapy with miconazole should be reserved for highly selected patients with disseminated coccidioidomycosis who cannot receive amphotericin B.