Bastiaan Nuijen

Alternative formulations of paclitaxel

Paclitaxel, a novel antitumour agent, is active clinically against advanced ovarian and breast cancer and under investigation for various other cancers. One of the problems associated with the intravenous administration of paclitaxel is its low solubility in water. The current pharmaceutical formulation consists of a 1:1 (v/v) mixture of ethanol and Cremophor EL. This formulation, however, has been demonstrated to cause some severe hypersensitivity reactions. Therefore the development of a safer intravenous formulation devoid of Cremophor EL is an important investigational issue. This review deals with some of the most promising formulation alternatives.

Progress in the development of alternative pharmaceutical formulations of taxanes.

The currently available taxanes paclitaxel(Taxol®) and docetaxel(Taxotere®) are clinically effectiveagainst advanced breast, ovarian andnon-small cell lung cancer. Due to theirlow aqueous solubility, both taxanes poseddifficulties to the pharmaceuticalscientists with respect to the developmentof an intravenous dosage form. At present,paclitaxel is formulated in a mixture of50:50% (v/v) Cremophor EL and dehydratedethanol. However, this formulation vehicleis associated with a number ofpharmacological, pharmacokinetic andpharmaceutical concerns amongst whichserious hypersensitivity reactions. Thisreview deals with the attempts made intothe development of alternative dosage formsof paclitaxel devoid of the CremophorEL/ethanol excipients and potential futuretaxane formulations.

Liposomal Drug Formulations in the Treatment of Rheumatoid Arthritis

Liposomes have been extensively investigated as drug delivery systems in the treatment of rheumatoid arthritis (RA). Low bioavailability, high clearance rates and limited selectivity of several important drugs used for RA treatment require high and frequent dosing to achieve sufficient therapeutic efficacy. However, high doses also increase the risk for systemic side effects. The use of liposomes as drug carriers may increase the therapeutic index of these antirheumatic drugs. Liposomal physicochemical properties can be changed to optimize penetration through biological barriers and retention at the site of administration, and to prevent premature degradation and toxicity to nontarget tissues. Optimal liposomal properties depend on the administration route: large-sized liposomes show good retention upon local injection, small-sized liposomes are better suited to achieve passive targeting. PEGylation reduces the uptake of the liposomes by liver and spleen, and increases the circulation time, resulting in increased localization at the inflamed site due to the enhanced permeability and retention (EPR) effect. Additionally liposomal surfaces can be modified to achieve selective delivery of the encapsulated drug to specific target cells in RA. This review gives an overview of liposomal drug formulations studied in a preclinical setting as well as in clinical practice. It covers the use of liposomes for existing antirheumatic drugs as well as for new possible treatment strategies for RA. Both local administration of liposomal depot formulations and intravenous administration of passively and actively targeted liposomes are reviewed.

Pharmaceutical development and preliminary clinical testing of an oral solid dispersion formulation of docetaxel (ModraDoc001).

For use in chronic oral chemotherapeutic regimens, the potent anticancer drug docetaxel needs a solid oral dosage form. Because docetaxel has a very low permeability and a very low aqueous solubility (biopharmaceutical classification system class IV), a pharmacokinetic booster was combined with a newly developed solid dispersion formulation to improve the oral bioavailability of docetaxel. The best performing solid dispersion was a 1/9/1 w/w/w ternary mixture of docetaxel, polyvinylpyrrolidone (PVP)-K30 and sodium lauryl sulphate (SLS). In a phase I clinical trial, with ritonavir as pharmacokinetic booster, the docetaxel premix solution (TAXOTERE) was pharmacokinetically evaluated against the solid dispersion formulation filled into hard gelatin capsules (ModraDoc001 15 mg capsules). There were no significant differences between the pharmacokinetic parameters of docetaxel after administration of docetaxel premix solution or ModraDoc001 15 mg capsules, although there was a trend towards a higher and more variable exposure to docetaxel after oral administration of docetaxel premix solution (513 ± 219 vs. 790 ± 669 ngh/mL). The low inter-individual variability of docetaxel exposure (44%), the dosing accuracy, and the absence of ethanol and polysorbate are major advantages of ModraDoc001 15 mg capsules over docetaxel premix solution.

Shielding the cationic charge of nanoparticle-formulated dermal DNA vaccines is essential for antigen expression and immunogenicity

Nanoparticle-formulated DNA vaccines hold promise for the design of in vivo vaccination platforms that target defined cell types in human skin. A variety of DNA formulations, mainly based on cationic liposomes or polymers, has been investigated to improve transfection efficiency in in vitro assays. Here we demonstrate that formulation of DNA into both liposomal and polymeric cationic nanoparticles completely blocks vaccination-induced antigen expression in mice and ex vivo human skin. Furthermore, this detrimental effect of cationic nanoparticle formulation is associated with an essentially complete block in vaccine immunogenicity. The blocking of DNA vaccine activity may be explained by immobilization of the nanoparticles in the extracellular matrix, caused by electrostatic interactions of the cationic nanoparticles with negatively charged extracellular matrix components. Shielding the surface charge of the nanoparticles by PEGylation improves in vivo antigen expression more than 55 fold. Furthermore, this shielding of cationic surface charge results in antigen-specific T cell responses that are similar as those induced by naked DNA for the two lipo- and polyplex DNA carrier systems. These observations suggest that charge shielding forms a generally applicable strategy for the development of dermally applied vaccine formulations. Furthermore, the nanoparticle formulations developed here form an attractive platform for the design of targeted nanoparticle formulations that can be utilized for in vivo transfection of defined cell types.

Management of Hot Flashes in Patients Who Have Breast Cancer With Venlafaxine and Clonidine: A Randomized, Double-Blind, Placebo-Controlled Trial

PURPOSE Therapies for breast cancer may induce hot flashes that can affect quality of life. We undertook a double-blind, placebo-controlled trial with the primary objective of comparing the average daily hot flash scores in the twelfth week among patients treated with venlafaxine, clonidine, and placebo. Additional analyses of the hot flash score over the full 12 weeks of treatment were performed. PATIENTS AND METHODS In all, 102 patients with a history of breast cancer were randomly assigned (2:2:1) to venlafaxine 75 mg, clonidine 0.1 mg, or placebo daily for 12 weeks. Questionnaires at baseline and during treatment assessed daily hot flash scores, sexual function, sleep quality, anxiety, and depression. RESULTS After 12 weeks, a total of 80 patients were evaluable for the primary end point. During week 12, hot flash scores were significantly lower in the clonidine group versus placebo (P = .03); for venlafaxine versus placebo, the difference was borderline not significant (P = .07). However, hot flash scores were equal in the clonidine and venlafaxine groups. Over the course of 12 weeks, the differences between both treatments and placebo were significant (P <.001 for venlafaxine v placebo; P = .045 for clonidine v placebo). Frequencies of treatment-related adverse effects of nausea (P = .02), constipation (P = .04), and severe appetite loss were higher in the venlafaxine group. CONCLUSION Venlafaxine and clonidine are effective treatments in the management of hot flashes in patients with breast cancer. Venlafaxine resulted in a more immediate reduction of hot flash scores when compared with clonidine; however, hot flash scores at week 12 were lower in the clonidine group than in the venlafaxine group.

Pharmaceutical development of anticancer agents derived from marine sources.

The marine ecosystem is more and more acknowledged as a source of potential anticancer agents. After the identification of a potential substance several hurdles have to be overcome before a marine candidate can enter the clinic. Amongst these are the establishment of a method which ensures sufficient supply and, which is the focus of this review, the development of a clinically useful pharmaceutical formulation. General issues with respect to the pharmaceutical development of marine anticancer agents will be discussed, which will be illustrated by highlighting aspects of the pharmaceutical development and clinical use of some representative compounds.

A kinetic study of the chemical stability of the antimetastatic ruthenium complex NAMI-A

NAMI-A is a novel ruthenium complex with selective activity against cancer metastases currently in Phase I clinical trials in The Netherlands. The chemical stability of this new agent was investigated utilizing a stability-indicating reversed-phase high performance liquid chromatographic assay with ultraviolet detection and ultraviolet/visible light spectrophotometry. The degradation kinetics of NAMI-A were studied as a function of pH, buffer composition, and temperature. Degradation of NAMI-A follows first-order kinetics at pH<6 and zero-order kinetics at pH > or =6. A pH-rate profile, employing rate constants extrapolated to zero buffer concentration, was constructed, demonstrating that NAMI-A is most stable in pH region 3-4. The degradation rate is not significantly affected by specific buffer components. Storage temperature strongly influences the degradation rate.

Oral Anticancer Drugs: Mechanisms of Low Bioavailability and Strategies for Improvement

The use of oral anticancer drugs has increased during the last decade, because of patient preference, lower costs, proven efficacy, lack of infusion-related inconveniences, and the opportunity to develop chronic treatment regimens. Oral administration of anticancer drugs is, however, often hampered by limited bioavailability of the drug, which is associated with a wide variability. Since most anticancer drugs have a narrow therapeutic window and are dosed at or close to the maximum tolerated dose, a wide variability in the bioavailability can have a negative impact on treatment outcome. This review discusses mechanisms of low bioavailability of oral anticancer drugs and strategies for improvement. The extent of oral bioavailability depends on many factors, including release of the drug from the pharmaceutical dosage form, a drug’s stability in the gastrointestinal tract, factors affecting dissolution, the rate of passage through the gut wall, and the pre-systemic metabolism in the gut wall and liver. These factors are divided into pharmaceutical limitations, physiological endogenous limitations, and patient-specific limitations. There are several strategies to reduce or overcome these limitations. First, pharmaceutical adjustment of the formulation or the physicochemical characteristics of the drug can improve the dissolution rate and absorption. Second, pharmacological interventions by combining the drug with inhibitors of transporter proteins and/or pre-systemic metabolizing enzymes can overcome the physiological endogenous limitations. Third, chemical modification of a drug by synthesis of a derivative, salt form, or prodrug could enhance the bioavailability by improving the absorption and bypassing physiological endogenous limitations. Although the bioavailability can be enhanced by various strategies, the development of novel oral products with low solubility or cell membrane permeability remains cumbersome and is often unsuccessful. The main reasons are unacceptable variation in the bioavailability and high investment costs. Furthermore, novel oral anticancer drugs are frequently associated with toxic effects including unacceptable gastrointestinal adverse effects. Therefore, compliance is often suboptimal, which may negatively influence treatment outcome.

GMP production of pDERMATT for vaccination against melanoma in a phase I clinical trial

For the treatment of melanoma DNA vaccines are a promising therapeutic approach. In our institute a plasmid encoding a melanoma-associated epitope (MART-1) and an immunostimulatory sequence (tetanus toxin fragment-c) termed pDERMATT was developed. In a phase I study the plasmid will be administered intradermally using a newly developed tattoo strategy to assess the toxicity and efficacy of inducing tumor-specific T-cell immunity. To facilitate this study a Good Manufacturing Practice (GMP)-compliant plasmid manufacturing process was set up and a pharmaceutical dosage form was developed. Each batch resulted in approximately 200mg plasmid DNA of a high purity >90% supercoiled DNA, an A260/280 ratio 1.80-1.95, undetectable or extremely low residual endotoxins, Escherichia coli host cell protein, RNA, and DNA. In the manufacturing process no animal derived enzymes like RNase or potentially harmful organic solvents are used. After sterile filtration the concentration of the plasmid solution is approximately 1.1mg/mL. For the scheduled phase I study a concentration of 5mg/mL is desired, and further concentration of the solution is achieved by lyophilisation. The formulation solution is composed of 1mg/mL pDERMATT and 20mg/mL sucrose in Water for Injections. Upon reconstitution with a five times smaller volume an isotonic sucrose solution containing 5mg/mL pDERMATT is obtained. Lyophilised pDERMATT is sterile with >90% supercoiled DNA, an A260-280 ratio 1.80-1.95, content 90-110% of labeled, and residual water content <2% (w/w). The product yields the predicted profile upon restriction-enzyme digestion, is highly immunogenic as confirmed in an in vivo mouse model, and stable for at least six months at 5 degrees C. We have not only developed a reproducible process to manufacture pharmaceutical grade plasmid DNA but also a stable dosage form for the use in clinical trials.