ABSTRACT
OBJECTIVE: We evaluated the effects of glass and plastic containers on the physicochemical properties of parenteral nutrition lipid emulsions and total nutrient admixtures with an emphasis on globule size distribution and colloidal stability. METHODS: A commercial lipid emulsion, 20% ClinOleic, was separated into glass (type II soda-lime-silica) and plastic (polypropylene multilayer) containers, sterilized, and then stored for 16 wk at 40 degrees C. Globule size distribution, pH, and zeta potential measurements were made every 4 wk. Admixtures derived from parent lipid emulsions were tested after admixing (t = 0), storage for 7 d at 5 degrees C plus 24 h at 25 degrees C (t = 7 + 1), and then after an additional 3 d at 25 degrees C (t = 7 + 4). RESULTS: The parent lipid emulsions in glass and plastic containers exhibited identical time-dependent behavior with respect to mean globule size, percentage of oil droplets >or=5 mum, pH, and zeta potential measurements. The percentages of oil droplets >or=5 mum of all test conditions remained well below the United States Pharmacopeia <729> limits of 0.05%. The total nutrient admixture time-dependent physicochemical characteristics were also found to be independent of the parent lipid emulsion container type. CONCLUSION: Plastic and glass containers were found to be suitable, safe, and indistinguishable with respect to physicochemical stability of a representative parenteral nutrition lipid emulsion and total nutrient admixtures derived from the parent lipid emulsion.
Subject(s)
Drug Packaging/methods , Drug Stability , Fat Emulsions, Intravenous/chemistry , Glass/chemistry , Parenteral Nutrition , Plastics/chemistry , Drug Storage/methods , Humans , Hydrogen-Ion Concentration , Particle Size , SafetyABSTRACT
Electroporation is the transitory structural perturbation of lipid bilayer membranes due to the application of high voltage pulses. Its application to the skin has been shown to increase transdermal drug delivery by several orders of magnitude. Moreover, electroporation, used alone or in combination with other enhancement methods, expands the range of drugs (small to macromolecules, lipophilic or hydrophilic, charged or neutral molecules) which can be delivered transdermally. Molecular transport through transiently permeabilized skin by electroporation results mainly from enhanced diffusion and electrophoresis. The efficacy of transport depends on the electrical parameters and the physicochemical properties of drugs. The in vivo application of high voltage pulses is well tolerated but muscle contractions are usually induced. The electrode and patch design is an important issue to reduce the discomfort of the electrical treatment in humans.
Subject(s)
Drug Delivery Systems/methods , Electroporation , Pharmaceutical Preparations/administration & dosage , Skin/metabolism , Adjuvants, Pharmaceutic/chemistry , Adjuvants, Pharmaceutic/pharmacology , Administration, Cutaneous , Animals , Biological Transport/physiology , Humans , Pharmaceutical Preparations/chemistry , Pharmaceutical Preparations/metabolism , Technology, PharmaceuticalABSTRACT
The purpose was to achieve therapeutic fluxes of timolol by transdermal delivery using skin electroporation. The transdermal transport of timolol through human stratum corneum was studied in three compartment diffusion cells. The electrodes, buffer composition and pulse conditions were optimized. Timolol maleate concentration in the donor compartment was 40 mg/ml. Square wave pulses were applied. Electroporation enhanced the transdermal transport of timolol by 1-2 orders of magnitude as compared to passive diffusion. Even though the current application lasted for only 10 s, the transdermal transport remained high after pulsing for at least 6 h. Higher fluxes were obtained with Pt electrodes close to the skin and a phosphate buffer. 10 pulses of 400 V-10 ms were more efficient than 10 low voltage-long duration pulses. Therapeutic fluxes of timolol (>50 microg/cm(2) per h) through human stratum corneum were achieved by electroporation.
Subject(s)
Adrenergic beta-Antagonists/administration & dosage , Adrenergic beta-Antagonists/pharmacokinetics , Skin Absorption , Timolol/administration & dosage , Timolol/pharmacokinetics , Administration, Cutaneous , Buffers , Chromatography, High Pressure Liquid , Diffusion Chambers, Culture , Electrodes , Electroporation , Humans , Hydrogen-Ion Concentration , In Vitro Techniques , Iontophoresis , Models, Biological , Spectrophotometry, UltravioletABSTRACT
PURPOSE: The purpose of this work was to study the effect of electroporation on iontophoretic transport of two beta-blockers, timolol (lipophilic) and atenolol (hydrophilic), and to have a better understanding of the mechanism of combination. METHODS: The transdermal delivery of these beta-blockers through human stratum corneum was studied in three-compartment diffusion cells. The transport of mannitol was evaluated to assess the electroosmotic flow. RESULTS: The iontophoretic transport of timolol was decreased by electroporation because the high accumulation of the lipophilic cation timolol in the stratum corneum resulted in a decrease of electroosmosis. In contrast, electroosmosis was not affected by atenolol, and the iontophoretic transport of atenolol was increased by electroporation. CONCLUSIONS: Using two different beta-blockers, we showed that lipophilicity and positive charges affect the electrotransport of drugs. Understanding the effect of the physicochemical properties of the drug, as well as the electrical parameters, is thus essential for the optimization of transdermal drug delivery by a combination of electroporation and iontophoresis.
