Drug Safety
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Opioids have been accepted as appropriate treatment for acute and cancer pain, but their role in the management of chronic nonmalignant pain is the subject of much debate, mainly due to concerns about waning efficacy, the potential for neuropsychological impairment and the development of drug addiction. Controlled clinical trials demonstrated that opioids may be effective in both nociceptive and neuropathic noncancer pain, although the former responded more consistently than the latter. Gastrointestinal and CNS adverse effects were frequent in most studies. ⋯ The main consensus is that a subset of these patients may gain substantial benefit from opioid analgesics without requiring rapidly escalating doses or developing intolerable adverse effects or drug addiction. Prescribing guidelines have been developed to assist practitioners in selecting the appropriate patients and ensuring an acceptable risk : benefit ratio of opioid therapy. Finally, it must be emphasised that chronic pain is a complex entity wherein analgesics, including opioids, are only part of the treatment.
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A large number of drugs of different classes, ranging from antibacterials to chemotherapeutic agents to psoralens, can be responsible for the development of nail changes. Drug-induced nail changes usually involve several or all 20 nails and appear in temporal correlation with drug intake. Some nail changes are asymptomatic and only cause cosmetic problems, while others cause pain and discomfort and impair manual activities or deambulation. ⋯ Drugs that are well known to produce nail abnormalities include cancer chemotherapeutic agents, psoralens, retinoids, tetracyclines, antimalarials and zidovudine. Arsenic poisoning is also always associated with nail changes that have medico-legal importance. Some drugs taken during pregnancy may impair nail development of the fetus, and nail hypoplasia or other nail dystrophies will be evident in the newborn.
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The aetiology of cognitive impairment is multifactorial; however, drugs are an important cause of delirium and dementia. Several factors may increase the risk of drug-induced cognition disorders in the elderly including imbalances in neurotransmitters (e.g. acetylcholine), age-related alterations in pharmacokinetics and pharmacodynamics, and high levels of medication use. Nearly any drug can cause cognitive impairment in susceptible individuals; however, certain classes are more commonly implicated. ⋯ Although some drugs have shown low risk for causing cognition disorders in research studies, risk may be increased in frail older adults taking several medications and each case should be reviewed carefully. Identification of drug-induced cognitive impairment is crucial to early detection and resolution of symptoms. Preventive strategies directed at avoiding high risk medications when possible, appropriately adjusting doses based on age-related changes and close follow-up may prevent these conditions.
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The antidiabetic drug metformin has been associated in a small number of patients with lactic acidosis, a serious condition with a poor prognosis. However, because of lack of data, the prognostic significance of hyperlactataemia in metformin-treated patients is not known. ⋯ In this, the largest series of metformin-treated patients with lactic acidosis yet reported, 55% of patients survived and these patients had a median arterial lactate level of 13.1 mmol/L. Neither arterial lactate levels nor plasma metformin concentrations were of prognostic significance in relation to mortality in this sample of metformin-treated patients with lactic acidosis. Death in these patients appeared instead to be associated with other hypoxic disease or underlying ill health. These observations suggest that accumulation of metformin may not be as significant with respect to high arterial levels of lactate and their effects as has been traditionally thought.
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True complications of regional block procedures pertain to the performance of the block technique and the local anaesthetic. Such complications include lesions caused by the device used, and many of these complications can be avoided by using specifically designed devices. Complications related to the local anaesthetic solution mainly consist of local and systemic complications. ⋯ There are 2 other groups of disorders often reported as complications of regional anaesthetics: (i) effects that were not anticipated by the anaesthetist because of a lack of knowledge of all the consequences of the technique used; and (ii) complications attributed to a concomitant regional block procedure but with no established, sometimes even improbable, causal link with the regional technique. The overall morbidity of regional anaesthesia in children is low. Sound selection of local anaesthetics, insertion routes and block procedures, together with appropriate and careful monitoring, should prevent any major undesirable effects and enable regional anaesthesia to be a well tolerated and effective tool to overcome pain associated with minimal morbidity.