Toxicity synergistic effects

When Hie cholinesterase inhibitors are administered with the anticholinergic drugp, there is a potential decrease in activity of the anticholinergic drug. There is an increased risk of toxicity of theophylline when the cholinesterase inhibitors are administered with tacrine There is a synergistic effect when tacrine is administered with succinyl-choline, cholinesterase inhibitors, or cholinergic agonists (eg, bethanechol). 

Cadmium also affects the toxicity of lead. A synergistic effect of these metals was found on prostatic cytology and testicular damage in male rats following intraperitoneal injection (Fahim and Khare 1980). Rats fed lead and cadmium or zinc had a marked reduction of reticulocytosis compared with rats fed lead alone (Thawley et al. 1977). Mice exposed simultaneously to lead and cadmium for 10 weeks had higher mortality rates than mice exposed to either metal alone (Exon et al. 1979). In addition, interactions between cadmium and lead have been reported at the behavioral effects level (Nation et al. 1990). 

The contribution of oxysterols to the cytotoxicity of oxidized LDL is likely, but it is to be noted that oxysterol concentrations necessary to trigger apoptosis in cultured cells are much higher than that reported in toxic concentrations of oxidized LDL and in atherosclerotic plaques (Brown and Jessup, 1999). This could be due to a synergistic effect of the different toxic molecules brought by the oxLDL. 

Halogenated derivates brominated organic compounds are the most used, often in combination with antimony trioxide to develop a synergistic effect. However, this generates a lot of smoke and toxic fumes, which is unacceptable for many regulations and standards. 

The role of bismuth(III) salts as Lewis acids has only been studied since the late 1980 s. Pioneering work by Dubac, Wada and others paved the way to wide and general methods using bismuth(III) catalysts. The versatile use of bismuth salts in synthesis has clearly been highlighted by the increasing number of publications in the field. The low toxicity of bismuth salts, associated with low cost, make them attractive and practical catalysts to use. Synergistic effects with other Lewis acids have also been recently highlighted. 

Mixtures of Toxicants, Polluted atmospheres are complex mixtures of many toxic and inert materials which may interact to increase or diminish plant injury. Menser and Heggestad (26) reported the first evidence of synergistic response when an ozone-susceptible tobacco strain was exposed to a mixture of ozone and sulfur dioxide. Other researchers have subsequently confirmed this response, but attempts to identify synergistic or antagonistic responses with other pollutants have been unsuccessful, although synergistic effects of NO2 and SO2 are suggested. 

Irinotecan has demonstrated a broad spectrum of activity in vitro and in vivo, and synergistic effects have been observed when it is administered in combination with other antineoplastic agents. Clinically irinotecan is now an active agent in patients with colorectal carcinoma. Irinotecan is metabolized by carboxylesterase to an active metabolite. It is cleared by hepatic metabolism and biliary excretion with a terminal elimination half-life of approximately 15 hours. The principal toxicities associated with irinotecan are diarrhoea and leucopenia. 

---