Acute Toxicity Testing by the Dermal Route
Rhoda G. M. Wang, James B. Knaak, Howard I. Maibach in Health Risk Assessment, 2017
Increases in toxicity do not always follow extended dermal exposure times, however. In a comparative study using 30 chemicals,26 4- and 24-h rat dermal LD50s were quite similar (correlation coefficient = 0.90) as were 4- and 24-h rabbit dermal LD50s (correlation coefficient = 0.82). (Interestingly, the rabbit LD50s were generally well below the rat LD50s even though the contact times were much shorter for the rabbit — further evidence of the greater sensitivity of the rabbit as discussed earlier). Another example was the percutaneous toxicity evaluation of bis[2-(dimethylamino)-ethyl]ether.27 The 4-h LD50s were 0.41 ml/kg and 0.63 ml/kg for male and female rabbits, respectively; 24-h tests resulted in an LD50 of 0.37 ml/kg for both sexes. These values were judged to be statistically equivalent. Several explanations may be offered as to the occasional lack of correlation between contact period and toxicity (or absorption).28,29 Dermal penetration may be rapid (and relatively complete), the sample may evaporate after a short time, the saturation of metabolic pathways may limit the degree of conversion to a more toxic product, the skin may become less penetrable due to local changes, or there may be some absorptive limits in the skin (such as saturation of the dermal reservoir) or limits in general circulation.
Concentration Methods
Donald L. Price in Procedure Manual for the Diagnosis of Intestinal Parasites, 2017
The use of the centrifuge improved sedimentation procedures and such procedures proved to be especially good for operculate and schistosome eggs. A variety of solutions were used for improving the sedimentation of various stages of parasites (see Ash and Orihel, 1987). In most procedures, ethyl ether was used in combination with the solution to help separate eggs, cysts, and juvenile worms from the fecal matter and to remove fatty material and some debris from the sediment. One or two drops of a surfactant, usually 20% Triton X-100, may be added to help separate organisms from mucus and fatty materials. Some methods (special solutions) were developed to concentrate eggs of certain species or types, such as schistosomes. These special methods are not usually appropriate for routine work.
Liposome-Based Nanocarrier System for Phytoconstituents
Madhu Gupta, Durgesh Nandini Chauhan, Vikas Sharma, Nagendra Singh Chauhan in Novel Drug Delivery Systems for Phytoconstituents, 2020
Another approach in improving encapsulation efficiency and capacity is the reverse phase evaporation method. The organic phase, containing the dissolved lipids, and aqueous phase are mixed together with the help of sonication to form water in oil emulsion at the first step of this method. The organic solvents used are usually diethyl ether or isopropyl ether, or a mixture of isopropyl ether and chloroform. This leads to the formation of inverted micelles within the emulsion. The organic solvent is then removed under reduced pressure, which results into conversion of inverted micelles into viscous gel state. Residual solvent is removed through continued rotary evaporation under reduced pressure. Liposomes are formed at that point when the excess of phospholipids forms the second half of the bilayer (Szoka et al., 1978). For example, a comparison between 5-FU encapsulation by freeze-thawed and reverse phase evaporation method results in a higher encapsulation efficiency for the latter method (Elorza et al., 1993). In another study, reverse phase evaporation method was compared with lipid film hydration method in the encapsulation efficiency of sodium cromoglycate and sumatriptan succinate (Villasmil-Sánchez et al., 2013). In the end, reverse phase evaporation method was proved to have remarkably higher encapsulation efficiency for both small molecule therapeutics. Another author assessed various techniques including lipid film hydration, ether injection and double emulsion in the entrapment of salvinolic acid B, and came to the conclusion that the highest encapsulation efficiency was obtained by reverse phase evaporation (Zhang et al., 2012).
Development and characterization dual responsive magnetic nanocomposites for targeted drug delivery systems
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Lida Ahmadkhani, Abolfazl Akbarzadeh, Mojtaba Abbasian
PEG-RAFT agent was used as CTA in the RAFT polymerization of N-isopropyl acrylamide and MA monomers. For synthesis of poly [(PMA-PNIPAM)m-b-PEG-b-(PNIPAM-PMA)m] triblock terpolymer, PEG-RAFT agent (0.45 g, 0.11 mmol), NIPAM (2.0 g, 17.7 mmol), MA (1.5 g, 17.7 mmol) and AIBN (3.6 mg, 0.022 mmol) were dissolved in THF (4 ml) in a 100 ml round bottom flask. The reaction flask temperature is raised to 70 °C and stirred for 24 h, after deoxygenation of the solution. After 24 h, the reaction flask was cooled to ambient temperature and was opened to air in order to stop the polymerization reaction. The reaction mixture was decanted into excess diethyl ether. The produce was purified twice by dissolution/precipitation with dichloromethane/diethyl ether and then dried in a vacuum for 24 h. (2.34 g, 82%) (Scheme 1 (II)).
Electrostatic hazards of charging of bedclothes and ignition in medical facilities
Published in International Journal of Occupational Safety and Ergonomics, 2019
Yuta Endo, Atsushi Ohsawa, Mizuki Yamaguma
Since highly flammable anesthetics such as diethyl ether and cyclopropane have been used in hospitals in the past, there was a high risk of ignition due to static spark [1,2]. Although they are not in use currently, some flammable liquids such as antiseptics are still in use. In recent years, ignitions of petroleum benzine and alcohol-based hand sanitizer due to static spark have occurred in medical facilities in Japan, the USA and Sweden [3–7]. In an ignition accident of petroleum benzine, the victims (a patient and a nurse) got second-degree burns [3]. In the cases involving alcohol-based hand sanitizer, medical workers touched a grounded metal object such as a door knob, while wet with hand sanitizer, and received a light burn on the hand [4–6]; in addition, a patient suffered third-degree burns due to the patient’s clothes being wet with spilled hand sanitizer [7].
Gynura procumbens ethanol extract improves vascular dysfunction by suppressing inflammation in postmenopausal rats fed a high-fat diet
Published in Pharmaceutical Biology, 2021
Khuzaidatul Azidah Ahmad Nazri, Qodriyah Haji Mohd Saad, Norsyahida Mohd Fauzi, Fhataheya Buang, Ibrahim Jantan, Zakiah Jubri
Animals were randomly divided into eight groups comprising of six animals per group: sham rats; (i) control, (ii) 250 mg/kg GP, (iii) 500 mg/kg GP, (iv) atorvastatin (AVT); and postmenopausal rats; (v) PM, (vi) PM + 250 mg/kg GP, (vii) PM + 500 mg/kg GP, (viii) PM + ATV groups. Each group received either 250 or 500 mg/kg of GP or ATV at 10 mg/kg by oral gavage for 6 months concurrently with or without 2% cholesterol chow mixed with 15% (w/w) of five-times heated palm oil (5HPO). GP or ATV was administered in a maximum volume of 1 mL to each rat accordingly (Ahmad Nazri et al. 2019). Toxicity effects from GP and ATV supplementation were verified by liver function test. During the treatment, the systolic blood pressure (SBP) was monitored, and blood was collected at the interval of three months. At the end of the treatment period (6 months), the rats were fasted overnight before being sacrificed by exposing them to a low concentration of diethyl ether from a vaporizer (Yadav and Sisodia 2020). Inhalation of low concentration of diethyl ether for at least 2 min could lessen the irritation to the rats (Aguwa et al. 2020).
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