Cns Drugs
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Bipolar depression is the predominant abnormal mood state in bipolar disorder. However, despite the key pertinence of this phase of the condition, the focus of research and indeed of clinical interest in the management of bipolar disorder has been mainly on mania. Bipolar depression has been largely neglected, and early studies often failed to distinguish depression due to major unipolar depression from that due to bipolar disorder. ⋯ If this fails, then novel strategies or ECT should be considered. Bipolar depression is a disabling illness and the predominant mood state for the vast majority of those with bipolar disorder. It therefore warrants prompt management once suitably diagnosed, especially as it is associated with a considerable risk of suicide and in the majority of instances is eminently treatable.
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The principal constituent of cannabis, Delta(9)-tetrahydrocannabinol (THC), is moderately effective in treating nausea and vomiting, appetite loss, and acute and chronic pain. Oral THC (dronabinol) and the synthetic cannabinoid, nabilone, have been registered for medical use in the US and UK, but they have not been widely used because patients find it difficult to titrate doses of these drugs. Advocates for the medical use of cannabis argue that patients should be allowed to smoke cannabis to relieve these above-mentioned symptoms. ⋯ However, this would be contrary to international drug control treaties and is electorally unpopular. The best prospects for the medical use of cannabinoids lie in finding ways to deliver THC that do not involve smoking and in developing synthetic cannabinoids that produce therapeutic effects with a minimum of psychoactive effects. While awaiting these developments, patients with specified medical conditions could be given exemptions from criminal prosecution to grow cannabis for their own use, at their own risk.
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Gabapentin is a structural analogue of the neurotransmitter gamma-aminobutyric acid (GABA) approved for use in adults with postherpetic neuralgia. Gabapentin does not bind to GABA(A) or GABA(B) receptors. Its mechanism of action in humans is unclear, but may involve binding to alpha2delta calcium channel subunits in animal models. ⋯ The proportion of responders (patients showing a > or =50% reduction in mean daily pain score at endpoint versus baseline) was significantly greater with gabapentin than placebo. Daily sleep rating scores, the Short Form McGill Pain Questionnaire (total pain scores), Patient and Clinician Global Impression of Change and measures on the Short Form-36 Health Survey (including physical functioning, role-physical, bodily pain, vitality or mental health) improved to a significantly greater extent with gabapentin than placebo. Adverse events associated with gabapentin in patients with postherpetic neuralgia were usually mild to moderate in intensity, with dizziness, somnolence and peripheral oedema being commonly reported.
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Propofol (Diprivan) is a phenolic derivative with sedative and hypnotic properties but is unrelated to other sedative/hypnotic agents. Formulated as an oil-in-water emulsion for intravenous use, it is highly lipophilic and rapidly crosses the blood-brain barrier resulting in a rapid onset of action. Emergence from sedation is also rapid because of a fast redistribution into peripheral tissues and metabolic clearance. The depth of sedation increases in a dose-dependent manner. In well designed clinical trials in patients receiving sedation in the intensive care unit (ICU) for a variety of indications, propofol provided adequate sedation for a similar proportion of time to midazolam, but the rate of recovery was faster with propofol. Even after periods of prolonged sedation (>72 hours), propofol was generally associated with a faster time to recovery than midazolam. Propofol facilitated better predictability of recovery and an improved control of the depth of sedation in response to titration than midazolam. In patients sedated following head trauma, propofol reduced or maintained intracranial pressure. Propofol is associated with generally good haemodynamic stability but induces a dose-dependent decrease in blood pressure and heart rate. Bolus administration may cause transient hypotension, and slow initial infusions are recommended in most patients. Serum triglyceride concentrations should be monitored during prolonged infusions (>3 days) because of the risk of hypertriglyceridaemia. The administration of 2% propofol can reduce this risk. Strict aseptic technique must be used during the handling of the product to prevent accidental extrinsic microbial contamination. Despite a higher acquisition cost with propofol, most studies of short-term sedation (approximately <3 days) showed that overall costs were lower with propofol than with midazolam, because a faster time to extubation reduced total ICU costs. However, as the period of sedation increased, the cost difference decreased. ⋯ The efficacy of propofol in the sedation of adults in the ICU is well established, and clinical trials have demonstrated a similar quality of sedation to midazolam. Because of a rapid distribution and clearance, the duration of action of propofol is short and recovery is rapid. Emergence from sedation is more rapid with propofol than with midazolam, even after long-term administration (>72 hours), which enables better control of the depth of sedation in response to titration and more predictable recovery times. Thus, for the ICU sedation of adults in a variety of clinical settings, propofol provides effective sedation with a more rapid and predictable emergence time than midazolam.