Overexcitement and disinhibition: dynamic neurotransmitter interactions in alcohol withdrawal

Article Abstract:

Withdrawal from alcohol causes profound effects upon the system that transmits nerve signals. Different neurotransmitter and receptor abnormalities that are found in conjunction with alcohol withdrawal have been linked to reduced inhibitory and increased excitatory functions. At an excitatory synapse, the (postsynaptic) response to a neurotransmitter brings the cell membrane potential closer to threshold, so that positively charged ions are free to move across it. Activation of an inhibitory synapse lessens the likelihood that the cell will generate an action potential. Activation of excitatory N-Methyl-D-aspartate (NMDA) brain receptors has been shown to be associated with seizure activity and brain cell death. Plasma magnesium (Mg), an inhibitory modulator, blocks effects of NMDA stimulation. Therefore, the low levels of Mg found in withdrawal are thought to be responsible for the increase in NMDA stimulation, which leads to seizure activity and delirium tremens (DTs). There is also evidence of reduction in gamma-aminobutyric acid (GABA) receptor function in chronic alcoholism. Since GABA is the major inhibitory neurotransmitter of the central nervous system (CNS), this leads to the increased excitatory states in withdrawal. Noradrenaline (NA) excitatory activity is also present in withdrawal. It is posited that increased NA levels may influence low Mg levels. Dopamine (DA) receptor sensitivity may also be increased in alcohol withdrawal, and contributes to hallucinations in DTs. The blockade of calcium channels during alcohol withdrawal has also been shown to increase some withdrawal symptoms, particularly seizures. Other neurotransmitter actions are also implicated in alcohol withdrawal, in which positive-feedback loops, such as the loop suggested by NA, Mg and NMDA interactions, lead to CNS excitability. Early treatment to reduce excitatory activity - for example with Mg supplementation - may prevent some of the most harmful effects of alcohol withdrawal. (Consumer Summary produced by Reliance Medical Information, Inc.)

Alcohol, Ethanol, Neurotransmitter receptors, Magnesium metabolism, Delirium tremens, Alcohol withdrawal delirium

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Acute blocking of naloxone-precipitated opiate withdrawal symptoms by methohexitone

Article Abstract:

Naloxone is an opiate antagonist drug, which can precipitate a withdrawal syndrome in opiate-dependent individuals. To see whether the acute onset of opiate withdrawal, induced by naloxone injection, could be overcome by co-medication with a barbiturate, 18 opiate-dependent patients (3 women, 15 men, aged 20-35 years) who had been addicted for 2 to 18 years were studied. Nine were randomly assigned to a naloxone group (A), and nine to a placebo group (B). They all received equal doses of morphine for two days, to ensure that no one began the study with withdrawal signs. On the third day, all received an injection of 100 milligrams of methohexitone (a barbiturate and general anesthetic). While anesthetized, they all received another injection of 400 mg methohexitone, immediately followed by injections of 10 mg naloxone (group A) or placebo (group B). When the narcotic effects of methohexitone had worn off, all were rated for withdrawal signs. Then, as a provocation test, 2 mg naloxone were administered to both groups. When the narcotic had fully worn off, the whole procedure was repeated. After this, all patients received equal doses of naloxone for 48 hours, and were observed for a week. When the methohexitone had worn off, Group B demonstrated only minimal withdrawal signs. However, in group B, the provocation test led to acute and severe withdrawal symptoms. In group A, after the barbiturate had worn off, and even after the provocation test, there were hardly any withdrawal signs. When both groups received naloxone for 48 hours after treatment, no increase in withdrawal symptoms was observed in either group. These results suggest a paradoxical pharmacological action of naloxone, since when it was administered with barbiturate anesthesia, high does prevented the onset of withdrawal signs. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Naloxone

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A double-blind comparison of the effects of gradual withdrawal of lorazepam, diazepam and bromazepam in benzodiazepine dependence

Article Abstract:

The potential for individuals to develop a dependence on benzodiazepines, a class of drugs commonly used to control anxiety, is well-known. However, it is difficult to predict who will develop such a dependence. Because of this, treatments are often limited to one month as a precaution, but some individuals do not appear to have difficulty withdrawing from these drugs. Several risk factors for benzodiazepine dependence have been identified. These include high dosage, long-term treatment, dependent personality features, high drug potency, and the use of benzodiazepines that wear off quickly (having a short half-life). These risk factors need further study. A study was designed involving 68 patients who had taken benzodiazepines for a period of six months or more and who showed symptoms of withdrawal upon reduction of dosage, which prevented them from discontinuing the drug, despite a desire to do so. The patients were divided into three groups; subjects were given lorazepam, diazepam, or bromazepam after a personality assessment was completed. In four weeks, dosage was reduced by 25 percent until complete withdrawal was accomplished at 10 weeks. Measures of anxiety and withdrawal symptoms were administered every two weeks. Twenty-three patients dropped out of the study before completion; 10 were in the lorazepam group (one patient committed suicide); seven each were in the diazepam and bromazepam groups. Of those remaining, withdrawal symptoms were more disturbing in those with dependent personality characteristics and in those who had taken the drug for five years or more. There were few significant differences between drugs in characteristic withdrawal symptoms. (Consumer Summary produced by Reliance Medical Information, Inc.)

Care and treatment, Methods, Risk factors, Clinical trials, Benzodiazepine abuse

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