Drug-induced respiratory disorders: incidence, prevention and management.

Various drugs are associated with adverse respiratory disorders (ARDs) ranging in severity from mild, moderate to severe and even fatal. Cardioselective and nonselective beta-blockers, calcium antagonists and dipyridamole can induce asthma. ACE inhibitors are mainly associated with cough. Amiodarone is related to a form of interstitial pneumonitis (IP) which can be fatal, tocainidine and flecainidine to a form of IP, and hydrochlorothiazide to a form of IP and pulmonary oedema. Antiasthmatic drugs can be associated with a paradoxical bronchospasm, while leukotriene antagonists are linked to the development of Churg-Strauss syndrome. Nonsteroidal anti-inflammatory drugs including aspirin (acetylsalicylic acid) may induce asthma. Gold is mainly related to IP, penicillamine to IP, systemic lupus erythematosus, bronchiolitis obliterans, and Goodpasture's syndrome. Acute respiratory reactions to nitrofurantoin include dyspnoea, cough, IP, and pleural effusion while IP and fibrosis are common in chronic reactions. Other antibacterials mainly evoke pneumonitis, pulmonary infiltrates and eosinophilia, and bronchiolitis obliterans. ARDs are similar for most categories of cytotoxic agents, with chronic pneumonitis and fibrosis being the most common. Noncardiogenic pulmonary oedema occurs as the most common respiratory complication in opioid agonist addiction. Psychotropic drugs such as phenothiazides, butyrophenones and tricyclic antidepressants can also induce pulmonary oedema. Oral contraceptives may produce asthma exacerbation, while long term use and/or high doses of postmenopausal hormone replacement therapy increase the risk of asthma. Bromocriptine is mainly associated with pleural effusion, while methysergide is usually associated with pleural effusion and fibrosis. Some anorectic agents have been linked to the development of primary pulmonary hypertension. The possibility of the occurrence of ARDs should be taken into account in each individual patient. Although in most cases the adverse effects are unpredictable, they can be reduced to a minimum or prevented if some drugs are avoided or stopped in time.     

Drug-induced urinary retention: incidence, management and prevention.

Urinary retention is a condition in which impaired emptying of the bladder results in postvoidal residual urine. It is generally classified into 'acute' or 'chronic' urinary retention. Because of the complex mechanism of micturition, many drugs can interact with the micturition pathway, all via different modes of action. Although the incidence of urinary retention, in particular acute urinary retention, has been well studied in observational studies and randomized controlled trials, data on the incidence of drug-induced urinary retention are scarce. Data from observational studies suggest that up to 10% of episodes might be attributable to the use of concomitant medication. Urinary retention has been described with the use of drugs with anticholinergic activity (e.g. antipsychotic drugs, antidepressant agents and anticholinergic respiratory agents), opioids and anaesthetics, alpha-adrenoceptor agonists, benzodiazepines, NSAIDs, detrusor relaxants and calcium channel antagonists. Elderly patients are at higher risk for developing drug-induced urinary retention, because of existing co-morbidities such as benign prostatic hyperplasia and the use of other concomitant medication that could reinforce the impairing effect on micturition. Drug-induced urinary retention is generally treated by urinary catheterization, especially if acute, in combination with discontinuation or a reduction in dose of the causal drug. Studies have been carried out examining the effects of preventive measures for anaesthesia-related urinary retention, both during and after surgery, particularly into the effect of using opioids in combination with non-opioid analgesic drugs on the incidence of postoperative urinary retention. Although combination therapy reduces the opioid-related adverse events, the effect on urinary retention yields contradictory results. This article reviews the literature on drug-induced urinary retention and focuses on its incidence, the different classes of drugs that have been associated with it, and options for its management and prevention.     

Drug-induced thrombotic microangiopathy: incidence, prevention and management.

The term thrombotic microangiopathy (TMA) describes syndromes characterised by microangiopathic haemolytic anaemia, thrombocytopenia and variable signs of organ damage due to platelet thrombi in the microcirculation. In children, infections with Shigella dysenteriae type 1 or particular strains of Escherichia coli are the most common cause of TMA; in adults, a variety of underlying causes have been identified, such as bacterial and viral infections, bone marrow and organ transplantation, pregnancy, immune disorders and certain drugs. Although drug-induced TMA is a rare condition, it causes significant morbidity and mortality. Antineoplastic therapy may induce TMA. Most of the cases reported are associated with mitomycin. TMA has also been associated with cyclosporin, tacrolimus, muromonab-CD3 (OKT3) and other drugs such as interferon, anti-aggregating agents (ticlopidine, clopidogrel) and quinine. The early diagnosis of drug-induced TMA may be vital. Strict monitoring of renal function, urine and blood abnormalities, and arterial pressure has to be performed in patients undergoing therapy with potentially toxic drugs. The drug must be discontinued immediately in the case of suspected TMA. Treatment modalities sometimes effective in other forms of TMA have been used empirically. Although plasma exchange therapy seems to be of value, the effectiveness of this approach has yet to be proved in multicentre, randomised clinical studies.     

Drug-induced rheumatic disorders: incidence, prevention and management.

The purpose of this article is to review the causes, the clinical manifestations and the management of the more frequent drug-induced rheumatic disorders. These include: (i) articular and periarticular manifestations induced by fluoroquinolones, nonsteroidal anti-inflammatory drugs, injections of corticosteroids, and retinoids; (ii) multisystemic manifestations such as drug-induced lupus and arthritis induced by vaccination, Bacillus Calmette-Guerin therapy and cytokines; (iii) drug-induced disorders of bone metabolism (corticosteroid-induced osteoporosis, drug-induced osteomalacia and osteonecrosis); and (iv) iatrogenic complex regional pain syndromes. Disorders caused by nonpharmacological and rarely used treatments have been deliberately excluded. Knowledge of these drug-induced clinical symptoms or syndromes allows an earlier diagnosis and treatment, and earlier drug withdrawal if necessary. With the introduction of new medications such as the recombinant cytokines and antiretroviral treatments, the number of drug-induced rheumatic disorders is likely to increase.     

Drug-induced pancreatitis : incidence, management and prevention

Drugs are a relatively rare cause of acute pancreatitis, with an estimated incidence of 0.1-2%. Many drugs have been suspected of causing pancreatitis, but the true incidence is not known as the evidence is derived mainly from random case reports. Case reports with the strongest evidence are those that clearly diagnose pancreatitis and exclude common aetiologies, provide the dose and time interval between the start of treatment with the suspected drug and the development of pancreatitis, document response to withdrawal of the drug, and demonstrate recurrent pancreatitis upon rechallenge with the drug. Few data exist on the mechanisms of drug-induced pancreatitis. Certain subpopulations such as children, women, the elderly and patients with advanced HIV infection or inflammatory bowel disease may be at higher risk. The diagnosis of drug-induced pancreatitis is often challenging because there are no unique clinical characteristics to distinguish drugs from other causes of pancreatitis. The majority of cases are mild, but severe and even fatal cases may occur, thus making identification of the offending agent critical. Management of drug-induced acute pancreatitis requires withdrawal of the offending agent and supportive care. Prevention of drug-induced pancreatitis requires an up-to-date knowledge of drugs that have the strongest evidence linking their use to the development of pancreatitis as well as the proposed mechanisms through which they may cause the reaction. In this paper, the epidemiology, diagnosis, management and prevention of drug-induced pancreatitis is reviewed. Drugs and classes of drugs strongly implicated as causing acute pancreatitis, based on well documented case reports, are discussed in detail.     

Drug-induced hyperhidrosis and hypohidrosis: incidence, prevention and management.

The human sweating response is subject to the influence of diverse classes of drugs. Some act centrally at the hypothalamus or at spinal thermoregulatory centres, while others act at sympathetic ganglia or at the eccrine-neuroeffector junction. Pharmacological disturbances of sweating have broad clinical implications. Drugs that induce hyperhidrosis, or sweating in excess of that needed to maintain thermoregulation, can cause patient discomfort and embarrassment, and include cholinesterase inhibitors, selective serotonin reuptake inhibitors, opioids and tricyclic antidepressants. Drugs that induce hypohidrosis, or deficient sweating, can increase the risk of heat exhaustion or heat stroke and include antimuscarinic anticholinergic agents, carbonic anhydrase inhibitors and tricyclic antidepressants. As acetylcholine is the principal neuroeccrine mediator, anhidrosis is one of the clinical hallmarks by which acute anticholinergic toxicity may be recognized. The symptom of dry mouth often accompanies the less apparent symptom of hypohidrosis because the muscarinic M(3) acetylcholine receptor type predominates at both sweat and salivary glands. Management options include dose reduction, drug substitution or discontinuation. When compelling medical indications require continuation of a drug causing hyperhidrosis, the addition of a pharmacological agent to suppress sweating can help to reduce symptoms. When hypohidrotic drugs must be continued, deficient sweating can be managed by avoiding situations of heat stress and cooling the skin with externally applied water. The availability of clinical tests for the assessment of sudomotor dysfunction in neurological disease has enhanced recognition of the complex effects of drugs on sweating. Advances in the understanding of drug-induced anhidrosis have also enlarged the therapeutic repertoire of effective treatments for hyperhidrosis.     

Drug-induced cutaneous photosensitivity: incidence, mechanism, prevention and management.

The interaction of sunlight with drug medication leads to photosensitivity responses in susceptible patients, and has the potential to increase the incidence of skin cancer. Adverse photosensitivity responses to drugs occur predominantly as a phototoxic reaction which is more immediate than photoallergy, and can be reversed by withdrawal or substitution of the drug. The bias and inaccuracy of the reporting procedure for these adverse reactions is a consequence of the difficulty in distinguishing between sunburn and a mild drug photosensitivity reaction, together with the patient being able to control the incidence by taking protective action. The drug classes that currently are eliciting a high level of adverse photosensitivity are the diuretic, antibacterial and nonsteroidal anti-inflammatory drugs (NSAIDs). Photosensitising chemicals usually have a low molecular weight (200 to 500 Daltons) and are planar, tricyclic, or polycyclic configurations, often with heteroatoms in their structures enabling resonance stabilisation. All absorb ultraviolet (UV) and/or visible radiation, a characteristic that is essential for the chemical to be regarded as a photosensitiser. The photochemical and photobiological mechanisms underlying the adverse reactions caused by the more photoactive drugs are mainly free radical in nature, but reactive oxygen species are also involved. Drugs that contain chlorine substituents in their chemical structure, such as hydrochlorthiazide, furosemide and chlorpromazine, exhibit photochemical activity that is traced to the UV-induced dissociation of the chlorine substituent leading to free radical reactions with lipids, proteins and DNA. The photochemical mechanisms for the NSAIDs that contain the 2-aryl propionic acid group involve decarboxylation as the primary step, with subsequent free radical activity. In aerated systems, the reactive excited singlet form of oxygen is produced with high efficiency. This form of oxygen is highly reactive towards lipids and proteins. NSAIDs without the 2-arylpropionic acid group are also photoactive, but with differing mechanisms leading to a less severe biological outcome. In the antibacterial drug class, the tetracyclines, fluoroquinolones and sulfonamides are the most photoactive. Photocontact dermatitis due to topically applied agents interacting with sunlight has been reported for some sunscreen and cosmetic ingredients, as well as local anaesthetic and anti-acne agents. Prevention of photosensitivity involves adequate protection from the sun with clothing and sunscreens. In concert with the preponderance of free radical mechanisms involving the photosensitising drugs, some recent studies suggest that diet supplementation with antioxidants may be beneficial in increasing the minimum erythemal UV radiation dose.     

Drug-induced oesophageal disorders: pathogenesis, incidence, prevention and management.

Drug-induced injury of the oesophagus is a common cause of oesophageal complaints. 'Pill-induced' oesophagitis is associated with the ingestion of certain drugs and accounts for many cases of erosive oesophagitis. To date, more than 70 drugs have been reported to induce oesophageal disorders. Antibacterials such as doxycycline, tetracycline and clindamycin are the offending agents in more than 50% of cases. Other commonly prescribed drugs that cause oesophageal injury include aspirin (acetylsalicylic acid), potassium chloride, ferrous sulfate, quinidine, alprenolol and various steroidal and nonsteroidal anti-inflammatory agents. However, many physicians and even more patients are not aware of this problem. Capsules or tablets are commonly delayed in their passage through the oesophagus. Highly caustic coatings, direct medication injury and poor oesophageal clearance of pills can lead to acute inflammation. Oesophageal damage occurs when the caustic contents of a drug remain in the oesophagus long enough to produce mucosal lesions. Taking medications at bedtime or without fluids is a common cause of oesophagitis. The possibility of drug-related damage should be suspected in all cases of oesophagitis, chest pain and dysphagia. History and gastrointestinal endoscopy will confirm the diagnosis. Treatment is supportive, although acid reduction is used frequently as an adjunct. This review reflects the current state of knowledge in this field.     

Drug-induced cognition disorders in the elderly: incidence, prevention and management.

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. Benzodiazepines, opioids, anticholinergics, and tricyclic antidepressants are probably the worst offenders. Older antihypertensive agents (reserpine, clonidine) have negative effects on cognition; however, large clinical trials in the elderly indicate that commonly used agents [e.g. thiazide diuretics, calcium antagonists (amiodipine, diltiazem), ACE inhibitors (captopril, enalapril) and beta-blockers (atenolol)] have minimal effects on cognition. Newer antidepressants such as selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs) and reversible inhibitors of monoamine oxidase A have not been shown to have negative effects on cognition. 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.     

Drug-induced nail disorders: incidence, management and prognosis.

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. Drug-induced nail abnormalities are usually transitory and disappear with drug withdrawal, but sometimes persist in time. The pathogenesis of the nail changes is usually a toxic effect of the drug on the different nail constituents, but other mechanisms can be involved. 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.     

药源性腹泻的发生机理和防治

药源性腹泻是一种常见的不良反应,占所有药物不良反应的7%[1]。它是指由于药物或药物相互作用引起粪便次数异常增多,且粪便可为水样或带有黏液、血性水样便或见有伪膜,可伴有腹痛、腹胀、恶心、呕吐,严重者可有寒颤、高热、昏迷、休克甚至死亡。因此,凡是能使胃肠道黏膜受损或胃肠道功能紊乱的药物都可引起药物性腹泻。它分为急性和慢性两类。急性腹泻起病急,通常在用药初期出现,病程短;慢性腹泻在用药后较长一段时间出现,病程可持续数周或数月,影响患者的生活质量。本文简要介绍药源性腹泻的致泻机理、部分相关药物及其防治。1药源性腹泻的…     

Drug-induced renal calculi: epidemiology, prevention and management

Drug-induced calculi represent 1-2% of all renal calculi. The drugs reported to produce calculi formation may be divided into two groups. The first one includes poorly soluble drugs with high urine excretion that favours crystallisation in the urine. Among poorly soluble molecules, triamterene was the leading cause of drug-containing urinary calculi in the 1970s, and it is still currently responsible for a significant number of calculi. In the last decade, drugs used for the treatment of HIV-infected patients, namely indinavir and sulfadiazine, have become the most frequent cause of drug-containing urinary calculi. Besides these drugs, about twenty other molecules may induce nephrolithiasis in patients receiving long-term treatment or high doses. Calculi analysis by physical methods, including infrared spectroscopy or x-ray diffraction, is needed to demonstrate the presence of the drug or its metabolites within the calculi. The second group includes drugs that provoke urinary calculi as a consequence of their metabolic effects. Here, diagnosis relies on careful clinical inquiry because physical methods are ineffective to differentiate between urinary calculi induced by the metabolic effects of a drug and common metabolic calculi. The incidence of such calculi, especially those resulting from calcium/vitamin D supplementation, is probably underestimated. Although drug-induced urinary calculi most often complicate high-dose, long-duration drug treatments, there also exist specific patient risk factors in relation to urine pH, urine output and other parameters, which provide a basis for preventive or curative treatment of calculi. Better awareness of the possible occurrence of lithogenic complications, preventive measures based on drug solubility characteristics and close surveillance of patients on long-term treatment with drugs with lithogenic potential, especially those with a history of urolithiasis, should reduce the incidence of drug-induced nephrolithiasis.     

药源性睡行症的常见致病药物及防治

睡行症是一种在睡眠中出现的以行走或其他异常行为或活动为特征的睡眠障碍（sleep disorder），通常发生在非快速眼动睡眠的慢波期。由药物引起的睡行症称之为药源性睡行症。引起药源性睡行症的常见药物有镇静催眠药、抗精神病药物以及抗抑郁症药等。据称，药源性睡行症的发生由多因素所致，包括既往睡行症发作史，应用增加慢波睡眠的药物以及体内外刺激。药源性睡行症的发生机制尚不清楚，有人认为是某些神经递质如5-羟色胺、1-氨基丁酸增加慢波睡眠所致。药源性睡行症防治原则包括：减少致病药物的剂量或停药，排除危险因素，加强环境安全及给予苯二氮[艹卓]革类药物。     

Anticonvulsant hypersensitivity syndrome: incidence, prevention and management.

Although the anticonvulsant hypersensitivity syndrome was first described in 1950, confusion still abounds regarding the syndrome. The triad of fever, rash and internal organ involvement occurring 1 to 8 weeks after exposure to an anticonvulsant heralds this rare (1 in 1,000 to 10,000 exposures) but serious reaction. Aromatic anticonvulsants [phenytoin, phenobarbital (phenobarbitone) and carbamazepine] are the most frequently involved drugs; however, there have also been several cases of anticonvulsant hypersensitivity syndrome associated with lamotrigine. Fever, in conjunction with malaise and pharyngitis, is often the first sign. This is followed by a rash which can range from a simple exanthem to toxic epidermal necrolysis. Internal organ involvement usually involves the liver, although other organs such as the kidney, CNS or lungs may be involved. Hypothyroidism may be a complication in these patients approximately 2 months after occurrence of symptoms. The aromatic anticonvulsants are metabolised to hydroxylated aromatic compounds, such as arene oxides. If detoxification of this toxic metabolite is insufficient, the toxic metabolite may bind to cellular macromolecules causing cell necrosis or a secondary immunological response. Cross-reactivity among the aromatic anticonvulsants may be as high as 75%. In addition, there is a familial tendency to hypersensitivity to anticonvulsants. Discontinuation of the anticonvulsant is essential in patients who develop symptoms compatible with anticonvulsant hypersensitivity syndrome. A minimum battery of laboratory tests, such as liver transaminases, complete blood count and urinalysis and serum creatinine, should be performed. Corticosteroids are usually administered if symptoms are severe. Patients with anticonvulsant hypersensitivity syndrome should avoid all aromatic anticonvulsants; benzodiazepines, valproic acid (sodium valproate) or one of the newer anticonvulsants can be used for seizure control. However, valproic acid should be used very cautiously in the presence of hepatitis. There is no evidence that lamotrigine cross-reacts with aromatic anticonvulsants. In addition, family counselling is a vital component of patient management.     

药源性头痛的发生原因、致病药物及防治

药源性头痛系指药物直接或间接引发的头痛，约占全部头痛患者的5％-10％。药源性头痛发生的机制尚不清楚，其发生的常见原因如下：血管扩张、良性颅内压增高、无菌性脑膜炎、双硫仑样反应以及过度使用镇痛药。药源性头痛的临床表现，除有头痛症状外，也可伴有头晕、恶心、呕吐、面部潮红、血压下降等。常见的致病药物有非甾体抗炎药、组胺H2受体拮杭荆、钙离子拮抗剂及血管扩张剂。药物治疗中出现头痛应注意将其与原发病所致头痛相区别。及时停药和对症处理可缓解药源性头痛症状。     

Protease inhibitor-induced diabetic complications : incidence, management and prevention.

Protease inhibitors (PIs) have become a crucial element in the treatment of patients infected with HIV. However, the widespread use of PI therapy has also been associated with a number of metabolic adverse effects, including fat redistribution and hyperglycaemia. The objective of this review is a discussion of the incidence, pathophysiology, management and prevention of PI-associated hyperglycaemia. Initial case reports have been followed by large cross-sectional and cohort studies, which demonstrate that the incidence of PI-induced impaired glucose tolerance, as well as frank diabetes mellitus, is significant and demands attention. Investigations into the pathophysiology behind PI-associated hyperglycaemia have identified an underlying problem of insulin resistance that is presumably caused by both direct PI-induced mechanisms and lipotoxicity. Given this, clinical trials have explored the use of various classes of oral hypoglycaemic agents in the management of PI-induced diabetic complications, and the use of insulin therapy must be considered as well. Newer PI agents are also under development, with the hope of reducing metabolic adverse effects. In the meantime, prevention, in the form of dietary modification, regular physical activity and periodic screening for impaired glucose tolerance, must receive heightened attention in the care plan of patients receiving long-term PI therapy.     

Extrapyramidal symptoms with atypical antipsychotics : incidence, prevention and management.

The treatment of schizophrenia changed drastically with the discovery of antipsychotic medications in the 1950s, the release of clozapine in the US in 1989 and the subsequent development of the atypical or novel antipsychotics. These newer medications differ from their conventional counterparts, primarily based on their reduced risk of extrapyramidal symptoms (EPS). EPS can be categorised as acute (dystonia, akathisia and parkinsonism) and tardive (tardive dyskinesia and tardive dystonia) syndromes. They are thought to have a significant impact on subjective tolerability and adherence with antipsychotic therapy in addition to impacting function. Unlike conventional antipsychotic medications, atypical antipsychotics have a significantly diminished risk of inducing acute EPS at recommended dose ranges. These drugs may also have a reduced risk of causing tardive dyskinesia and in some cases may have the ability to suppress pre-existing tardive dyskinesia. This paper reviews the available evidence regarding the incidence of acute EPS and tardive syndromes with atypical antipsychotic therapy. Estimates of incidence are subject to several confounds, including differing methods for detection and diagnosis of EPS, pretreatment effects and issues surrounding the administration of antipsychotic medications. The treatment of acute EPS and tardive dyskinesia now includes atypical antipsychotic therapy itself, although other adjunctive strategies such as antioxidants have also shown promise in preliminary trials. The use of atypical antipsychotics as first line therapy for the treatment of schizophrenia is based largely on their reduced risk of EPS compared with conventional antipsychotics. Nevertheless, EPS with these drugs can occur, particularly when prescribed at high doses. The EPS advantages offered by the atypical antipsychotics must be balanced against other important adverse effects, such as weight gain and diabetes mellitus, now known to be associated with these drugs.     

Adverse drug reactions in patients with phaeochromocytoma: incidence, prevention and management.

The dangers of phaeochromocytomas are mainly due to the capability of these neuroendocrine tumours to secrete large quantities of vasoactive catecholamines, thereby increasing blood pressure and causing other related adverse events or complications. Phaeochromocytomas are often missed, sometimes only becoming apparent during therapeutic interventions that provoke release or interfere with the disposition of catecholamines produced by the tumours. Because phaeochromocytomas are rare, evidence contraindicating use of specific drugs is largely anecdotal or based on case reports. The heterogeneous nature of the tumours also makes adverse reactions highly variable among patients. Some drugs, such as dopamine D(2) receptor antagonists (e.g. metoclopramide, veralipride) and beta-adrenergic receptor antagonists (beta-blockers) clearly carry high potential for adverse reactions, while others such as tricyclic antidepressants seem more inconsistent in producing complications. Other drugs capable of causing adverse reactions include monoamine oxidase inhibitors, sympathomimetics (e.g. ephedrine) and certain peptide and corticosteroid hormones (e.g. corticotropin, glucagon and glucocorticoids). Risks associated with contraindicated medications are easily minimised by adoption of appropriate safeguards (e.g. adrenoceptor blockade). Without such precautions, the state of cardiovascular vulnerability makes some drugs and manipulations employed during surgical anaesthesia particularly dangerous. Problems arise most often when drugs or therapeutic procedures are employed in patients in whom the tumour is not suspected. In such cases, it is extremely important for the clinician to recognise the possibility of an underlying catecholamine-producing tumour and to take the most appropriate steps to manage and treat adverse events and clinical complications.     

Drug-induced myelosuppression : diagnosis and management.

Myelosuppression is a common and anticipated adverse effect of cytotoxic chemotherapy. It is a potential but rare idiosyncratic effect with any other drug, but there is a recognised association with a number of higher-risk agents which justify additional vigilance. Genetic risk factors are being identified which may predispose individuals to this reaction with particular drugs. As marker tests become available, dose adjustment or alternative treatment choices may help to avoid more severe reactions. Myelosuppression is potentially life threatening because of the infection and bleeding complications of neutropenia and thrombocytopenia. Strategies for monitoring, early detection, diagnostic confirmation and appropriate supportive care are well developed for cytotoxic therapy. Developments in antimicrobial chemotherapy, blood product transfusion support and growth factor therapy have improved outcomes. These advances are largely applicable to idiosyncratic drug-induced myelosuppression, reinforcing the importance of early recognition and referral to appropriate expertise. Many reactions will resolve on drug withdrawal with appropriate supportive care during the period of cytopenia. Prolonged marrow failure may require more specific treatment with intensive immunosuppression or consideration of bone marrow transplantation.