Successful treatment of beta-thalassemia requires two key elements: blood transfusion and iron chelation. Regular blood transfusions considerably expand the lifespan of patients, however, without the removal of the consequential accumulation of body iron, few patients live beyond their second decade. In 1963, the introduction of desferrioxamine (DFO), a hexadentate chelator, marked a breakthrough in the treatment of beta-thalassemia. DFO significantly reduces body iron burden and iron-related morbidity and mortality. DFO is still the only drug for general use in the treatment of transfusion dependent iron overload. However, its very short plasma half-life and poor oral activity necessitate special modes of application (subcutaneous or intravenous infusion) which are inconvenient, can cause local reactions and are difficult to be accepted by many patients. Over the past four decades, many different laboratories have invested major efforts in the identification of orally active iron chelators from several hundreds of molecules of synthetic, microbial or plant origin. The discovery of ferrithiocin in 1980, followed by the synthesis of the tridentate chelator desferrithiocin and proof of its oral activity raised a lot of hope. However, the compound proved to be toxic in animals. Over a period of about fifteen years many desferrithiocin derivatives and molecules with broader alterations led to the discovery of numerous new compounds some of which were much better tolerated and were more efficacious than desferrithiocin in animals, however, none was safe enough to proceed to the clinical use. The discovery of a new chemical class of iron chelators: The bis-hydroxyphenyltriazoles re-energized the search for a safe tridentate chelator. The basic structure of this completely new chemical class of iron chelators was discovered by a combination of rational design, intuition and experience. More than forty derivatives of the triazole series were synthesized at Novartis. These compounds were evaluated, together with more than 700 chelators from various chemical classes. Using vigorous selection criteria with a focus on tolerability, the tridentate chelator 4-[(3,5-Bis-(2-hydroxyphenyl)-1,2,4)triazol-1-yl]-benzoic acid (ICL670) emerged as an entity which best combined high oral potency and tolerability in animals. ICL670 is presently being evaluated in the clinic.
These results endorse the idea that highly selective Cox-2 inhibitors may be associated with lesser gastrointestinal side effects than conventional NSAIDs.
The effect of furosemide (Lasix) therapy on a standardized experimental cerebral edema, induced in rats by applying a cooling stamp to the right side of the skull over the right coronal suture by means of a stereotactic instrument, was examined. The hemispherically separated water and electrolyte contents of the brain were analyzed after 24 h. Following furosemide therapy, the behavior of these edema parameters was compared statistically with dexamethasone, glycerol and albumin. An increase of the water and sodium content, and a decrease of potassium was observed 24 h after the trauma, especially in the right hemisphere. Furosemide did not improve either the water content or the electrolyte balance. By contrast, the administration of dexamethasone, glycerol and albumin was followed by a significant improvement of the edema. In experiments with cats, the course of the edema and the effect of furosemide on the cold brain injury of the right hemisphere were observed by measuring the intracranial pressure (ICP) values, and by continuous monitoring of the EEG. The ventricular CSF pressure and epidural pressures were also recorded. The electrical brain activity was continuously compared with the course of the ICP by means of computer analysis. In addition, the blood osmolality and diuresis were monitored. The ICP increased rapidly after the trauma, establishing considerable pressure gradients, and the EEG power intensities decreased markedly on the right side. Histologically, there was an extended edema of the white matter of both hemispheres. The ICP was not lowered by single injections or high dose infusions of furosemide, and the EEG power intensities also did not improve. Infusions of large volumes of furosemide even resulted in an increase of ICP, but infusion of 40% sorbitol effected a rapid decrease of ICP and EEG recovery over the left hemisphere. Sorbitol infusion also caused a marked rise in the blood osmolality, whereas furosemide had no such effect. The results raise considerable doubts as to the propriety of the exclusive use of furosemide for cases of acute cerebral edema with raised ICP. The diuretic effect is insufficient to establish an osmotic gradient, and its general dehydrating effect does not acutely influence the ICP. The absence of effect on the experimental tissue edema would not appear to commend furosemide as basic therapy for cases of traumatic cerebral edema.
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