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Spectrophotometric determination of hydroxylamine and its derivatives in pharmaceuticals.

A sensitive spectrophotometric method for the determination of hydroxylamine is described. The method is based on the oxidation of hydroxylamine to nitrite using sodium arsenate under alkaline condition. The formed nitrite is determined based on the diazo coupling reaction between p-nitroaniline and N-(1-naphthyl)ethylenediamine dihydrochloride [NEDA]. The system obeys Beer's law over the concentration range 0-7 microg of hydroxylamine at 545 nm and the colour is stable for 3 h. The molar absorptivity of the colour system is found to be 6.7 x 10(4) l mol(-1) cm(-1). The relative standard deviation is 1.2% for ten determinations at 4 microg of hydroxylamine. Interferences due to various foreign ions have been studied and the method has been applied to the determination of hydroxylamine and its derivatives used in pharmaceutical formulations after hydrolysis.

Arsenates↗

Antidotal action of atropine sulfate against insecticide benfuracarb poisoning in rats.

The antidotal action of atropine sulfate and 2-pyridine aldoxime methiodide (2-PAM) against poisoning attributable to the new procarbamate insecticide benfuracarb [(ethyl N-[2,3-dihydro-2,2-dimethylbenzofuran-7-yloxycarbonyl (methyl) aminothio]-N-isopropyl-beta-alaninate] was compared utilizing rats as our experimental model. Both the intraperitoneal and oral administrations of these antidotes were examined after five, ten, fifteen and thirty minutes exposure periods, following treatment with benfuracarb at dose levels approximating LD50 and LD100. The results obtained demonstrate that both the intraperitoneal and oral administrations of atropine sulfate blocked or significantly reduced the toxic effects of benfuracarb and protected the animals from death. The intraperitoneal administration route appears to be more effective than was the oral route. In addition, the administration of atropine sulfate after the shorter period (up to 15 minutes), following exposure to benfuracarb, improved antidotal action, particularly with the LD100 dose of benfuracarb. It is suggested that atropine sulfate antagonizes benfuracarb poisoning by blocking acetylcholine (ACh) receptors, as many other carbamate insecticides, since benfuracarb was an in vivo cholinesterase (ChE) inhibitor and the toxic effect of benfuracarb was reduced by atropine sulfate. 2-PAM, however, did not significantly block or reduce the toxic effects of benfuracarb.

Administration, Oral↗

Aqueous humour pralidoxime mesylate (P2S) concentrations and intraocular tension following intramuscular P2S.

Small transient increases in rabbit intraocular tension were measured following intramuscular pralidoxime mesylate (P2S) at doses of 10, 40 or 100 mg/kg. Peak increases in tension showed some dose dependency, and although not statistically correlated with plasma or aqueous humour P2S concentrations the changes in tension followed the general time-concentration profile for P2S in these fluids. P2S was not detected in aqueous humour following 10 mg/kg, but at 40 and 100 mg/kg dose dependent concentrations were detected in aqueous humour. From experiments involving multiple injections of P2S there was no evidence for a cumulative effect of P2S on the eye. The results indicate that P2S can enter aqueous humour following its parenteral administration and is associated with changes in intraocular fluid dynamics. Whilst they also suggest that some ophthalmic side-effects of oxime therapy may be a consequence of a direct action of the oxime on the eye, they do not exclude contributions from actions at other sites.

Animals↗

Atropine sulfate and 2-pyridine aldoxime methylchloride elicit stress-induced convulsions and lethality in mice and guinea pigs.

The present study demonstrates that dose combinations of atropine sulfate and 2-pyridine aldoxime methylchloride (2-PAM), which do not produce any overt toxic effects on the behavior of mice or guinea pigs in a stable environment, elicit clonic-tonic convulsions and death when the animals are physically stressed by cold water swimming. Phenoxybenzamine (1-6 mg/kg), diazepam (0.625 and 1.25 mg/kg) and pilocarpine (2.5 and 5 mg/kg) significantly decreased (or abolished) the occurrence of atropine and 2-PAM stressed-induced convulsions and/or lethality. In contrast, propranolol (20 mg/kg), was ineffective in preventing either convulsions or lethality. Changes in plasma glucose levels and internal body temperature did not appear to explain the precipitation of convulsions or ensuing death. These results suggest that during acute physical stress, relatively low doses of atropine and 2-PAM produce toxic and lethal effects due to the activation of alpha-adrenergic mechanisms along with a concomitant inactivation of cholinergic mechanisms.

Animals↗

Actions and interactions of cholinolytics and cholinesterase reactivators in the treatment of acute organophosphorus toxicity.

Different drug combinations consisting of cholinolytic and a cholinesterase (ChE) reactivator provide greater therapeutic efficacy in acute organophosphorus (OP) poisoning in mice than when used alone. Maximum protection, as determined by a shift of the LD50 for the two OP agents, was observed with the cholinolytic benactyzine. A protection index (P.I.) of 42 was obtained when benactyzine was given along with obidoxime in diisopropylphosphorofluoridate (DFP) intoxication. With the more toxic OP agent soman (o-pinacolylmethylphosphonofluoridate), the same cholinolytic only offered a maximum P.I. of 3.2 when administered with HS-6, another bispyridinium ChE reactivator. This beneficial effect of benactyzine is possibly due to its greater antimuscarinic effect in the central nervous system than atropine or dexetimide.

Acute Disease↗

Protection from lethality and behavioral incapacitation resulting from intoxication by soman (pinacolyl methylphosphonofluoridate) and treatment with atropine sulfate and 2-PAM chloride in the guinea pig, cavia porcellus.

The lethal and incapacitating effects of the toxic organophosphorus (OP) agent, soman were evaluated in guinea pigs. The protective effects of the standard therapies atropine sulfate (ATR) and pralidoxime chloride (2-PAM) in minimizing or reducing soman-produced lethality and incapacitation (evaluated using a modification of the rat conditioned avoidance procedure) were also studied. At 0.75 and 1.5 LD50 soman was extremely toxic and fast-acting; its effects appeared within five minutes, and its lethal effects occurred within the first three hours. Therapeutic combinations of ATR (64 or 128 mg/kg) and 2-PAM (25 or 100 mg/kg) protected animals from the lethality of soman, but not from its incapacitating effects. However, therapeutic treatment with ATR and 2-PAM also produced a behavioral toxicity in its own right, an effect which lasted for at least three hours in the guinea pig. This behavioral toxicity was lessened by reducing ATR dosage from 128 to 64 mg/kg, but 2-PAM dosage did not influence the behavioral toxicity of the treatment combinations within the range of dosages studied.

Animals↗

Efficacy of oxime plus atropine treatment against soman poisoning in the atropinesterase-free rabbit.

The oximes pralidoxime chloride (2-PAM), MMB4, and HI-6 were evaluated in combination with atropine as treatments against soman poisoning in atropinesterase-free rabbits. Animals were challenged i.m. with 2 x LD50 soman and treated at the onset of toxic signs with 50 mumols/kg of oxime and 5 or 13 mg/kg atropine. Survival and time to death were compared at 48 hours post-soman challenge. Survival rates in MMB4 and HI-6 treated animals were higher than in 2-PAM-treated animals. The increase in survival was significant at the 13 mg/kg dose of atropine. MMB4 and HI-6 also significantly delayed time to death after soman compared to 2-PAM. The results suggest that MMB4 and HI-6 have potential as useful oximes for treating soman poisoning.

Animals↗

Five cases of intentional ingestion of 25 percent diazinon with treatment and recovery.

The use of atropine to block the effects of acetylcholine and pralidoxime chloride to restore cholinesterase in the blood, along with supportative therapy, intravenous fluids, and oxygen, prevented death in five cases of intentional ingestion of 25% diazinon. Treatment of such cases must be tailored to the condition of the patient, and all residual poison in the stomach must be removed as rapidly as possible with gastric lavage to prevent absorption of the poison.

Acetylcholine↗

Treatment of acute organophosphate poisoning: evidence of a direct effect on central nervous system by 2-PAM (pyridine-2-aldoxime methyl chloride).

Management of acute organophosphate poisoning in man includes rapid treatment with atropine and oximes. Oximes are thought to be unable to enter the central nervous system. We describe a case of parathion poisoning in a 3-1/2 year-old child and the effect of treatment with oxime 2-PAM (34 mg/kg) on EEG activity and clinical symptoms. The prompt improvement of cortical electrical activity documented by EEG could not be explained by any improvement of circulatory or respiratory function and has to be considered a direct effect of oximes on the central nervous system.

Brain↗

The intermediate syndrome in organophosphate poisoning: presentation of a case and review of the literature.

A dimethoate-poisoned woman gradually developed a moderately severe cholinergic crisis that was readily treated by atropine. After being symptom-free for nearly two days, she suffered from sudden life-threatening respiratory paresis and weakness of the facial, extraocular, neck flexor and proximal limb muscles. Muscarinic symptoms were absent. Cholinesterase inhibition was severe, and EMG revealed marked decrements at low rates of repetitive nerve stimulation, and increments at a high rate. The clinical course was compatible with the Intermediate Syndrome. This syndrome seems due to persistent cholinesterase inhibition presumably leading to combined pre- and postsynaptic impairment of neuromuscular transmission. Inadequate pralidoxime therapy is proposed but not established as contributory. Prolonged monitoring of respiratory function in patients poisoned by particular organophosphate agents is mandatory.

Adult↗