Over-the-counter analgesics: a toxicology perspective

Evaluation of use, comprehensibility and clarity of over-the-counter medicine labels: Consumers' perspectives and needs in Taiwan

An estimate of one third of preventable medication errors occurred annually due to patients' misunderstanding of use instructions. To safeguard consumers' over-the-counter (OTC) medicine use and to develop future initiatives, this study evaluated the use, comprehensibility and clarity of the information labels on OTC packages from consumers' perspectives in Taiwan. This cross-sectional study was conducted at 29 community pharmacies; 50 pharmacy clerkship students helped participant enrolment from June to September 2017. Participants (n = 470) were 20 years old or above, Mandarin speaking, and with specific OTC purchases. A face-to-face survey was administered to investigate the degree to which participants read the package labels and their comprehension of correct medicine use. An 11-item survey was used to measure participants' specific OTC purchases (3 items), the use (2 items), comprehensibility (1 item) and clarity (2 items) of OTC package labels, in addition to the sociodemographic information (3 items). Participants were also solicited to provide opinions regarding package label redesign. Descriptive statistics and logistic regressions were applied for analyses. Findings show that most (84.0%) participants read instruction labels before use, with indications (79.4%), drug names (64.5%) and dosage and administration (59.8%) being the top reads. Only 30.0% of the participants fully understood how to take the medicines correctly. Younger (OR = 1.033, p < .001) and female participants (OR = 1.965, p = .014) with a higher level of education (OR = 1.940, p = .034) tended to read package label information prior to purchase or use. Younger participants (OR = 1.030, p < .001) and those who read OTC medicine labels before use (OR = 2.317, p = .004) were more likely to correctly understand medicine use. The findings indicate that older, male adults with a lower level of education should be targeted to ensure their correct understanding of OTC labels. Pharmacists should recite pertinent label information and, concomitantly, ensure consumers' understanding when providing medicine counselling.

The modulation of transcriptional expression and inhibition of multidrug resistance associated protein 4 (MRP4) by analgesics and their primary metabolites

During the course of a toxic challenge, changes in gene expression can manifest such as induction of metabolizing enzymes as a compensatory detoxification response. We currently report that a single 400 mg/kg acetaminophen (APAP) dose to C57BL/6J mice led to an increase in multidrug resistance-associated (Mrp) 4 (Abcc4) mRNA 12 h after administration. Alanine aminotransferase, as a marker of liver injury, was also elevated indicating hepatotoxicity had occurred. Therefore, induction of Mrp4 mRNA was likely attributable to APAP-induced liver injury. Mrp4 has been shown to be upregulated during oxidative stress, and it is well-established that APAP overdose causes oxidative stress due to depletion of glutathione. Given the importance of Mrp4 upregulation as an adaptive response during cholestatic and oxidative liver injury, we next investigated the extent by which human MRP4 can be inhibited by the analgesics, APAP, diclofenac (DCF), and their metabolites. Using an in vitro assay with inside out human MRP4 vesicles, we determined that APAP-cysteine inhibited MRP4-mediated transport of leukotriene C₄ with an apparent IC₅₀ of 125 μM. APAP-glutathione also attenuated MRP4 activity though it achieved only 28% inhibition at 300 μM. Diclofenac acyl glucuronide (DCF-AG) inhibited MRP4 transport by 34% at 300 μM. The MRP4 in vitro inhibition occurs at APAP-cysteine and DCF-AG concentrations seen in vivo after toxic doses of APAP or DCF in mice, hence the findings are important given the role that Mrp4 serves as a compensatory response during oxidative stress following toxic challenge.

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Following 400 mg/kg APAP in mice, mean ALT 12 hours post-dose was 1,140 U/L

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A statistically significant increase in Mrp4 mRNA was observed 12 hours post-dose

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APAP-CYS inhibited human MRP4 transport of LTC4 with an IC₅₀ = 125 μM (Ki = 122 μM)

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APAP-GSH decreased MRP4 transport by 29% inhibition at 300 μM

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APAP, APAP-GLU, APAP-NAC, and APAP-SUL did not exhibit significant MRP4 inhibition

Cysteine/Glutathione Deficiency: A Significant and Treatable Corollary of Disease

Glutathione (GSH) deficiency may play a pivotal role in a variety of apparently unrelated clinical conditions and diseases. Orally administered N-acetylcysteine (NAC), which replenishes the cysteine required for GSH synthesis, has been tested in a large number of randomized placebo-controlled trials involving these diseases and conditions. This chapter focused on developing a base of evidence suggesting that NAC administration improves disease by increasing cysteine and/or GSH in a variety of diseases, thereby implying a significant role for GSH deficiency in the clinical basis of many diseases. To develop this base of evidence, we systematically selected studies which considered the hypothesis that the therapeutic efficacy for NAC is an indication that cysteine and/or GSH deficiency is a pathophysiological part of the diseases studied. In this manner we focus this chapter on explaining the biological mechanisms of NAC therapy in a wide variety of disorders and demonstrate its ubiquitous role in improving disease that involves disrupted GSH and/or cysteine metabolism.

Prevalence, sources and purpose of self-prescribed non-opioid analgesic among health professionals in Sokoto metropolis, Nigeria: a cause for concern

Background. Self-medication is defined as the use of medicines without a doctor’s prescription. The non-opioid analgesics (NOAs) constitute one of the most commonly self-prescribed drugs globally. This study aims to determine the prevalence of NOAs self-medication, and also explore the purpose and sources of the self-prescribed NOAs among health professionals in Sokoto metropolis, Nigeria.

Methods. Data obtained from a cross-section of 205 health professionals in Sokoto metropolis, Nigeria, were used for this study. The study tool used was a well-structured questionnaire. Data analysis was done using the SPSS version 20 software.

Results. Only 36.6% of the 205 subjects were within the age range of 26 to 30 years, 38.0% were nurses. The majority (85.9%) of the subjects had self-prescribed NOAs, of which 6.8% of them had a positive history treatment for NOA overdose. Patent medicine stores (43.0%) were reported to be the most common source of acquisition of self-prescribed NOAs. The majority (63.9%) of the subjects used NOAs to get relieved from headaches. Paracetamol (79.0%) and Diclofenac (65.9%) were the top two self-prescribed NOAs among the subjects.

Conclusion. Non-opioid analgesic self-prescription is a popular practice among health professionals in Sokoto metropolis, Nigeria. All the various routes of access (e.g. hospital pharmacy) to NOAs need to be revisited in order to curb the irrational use of NOAs in Nigerian society.

LC-MS/MS method development for quantitative analysis of acetaminophen uptake by the aquatic fungus Mucor hiemalis

Acetaminophen is a pharmaceutical, frequently found in surface water as a contaminant. Bioremediation, in particular, mycoremediation of acetaminophen is a method to remove this compound from waters. Owing to the lack of quantitative analytical method for acetaminophen in aquatic organisms, the present study aimed to develop a method for the determination of acetaminophen using LC-MS/MS in the aquatic fungus Mucor hiemalis. The method was then applied to evaluate the uptake of acetaminophen by M. hiemalis, cultured in pellet morphology. The method was robust, sensitive and reproducible with a lower limit of quantification of 5 pg acetaminophen on column. It was found that M. hiemalis internalize the pharmaceutical, and bioaccumulate it with time. Therefore, M. hiemalis was deemed a suitable candidate for further studies to elucidate its pharmaceutical tolerance and the longevity in mycoremediation applications.

Review article: prescribing medications in patients with cirrhosis - a practical guide

BACKGROUND

Most drugs have not been well studied in cirrhosis; recommendations on safe use are based largely on experience and/or expert opinion, with dosing recommendations often based on pharmacokinetic (PK) changes.

AIM

To provide a practical approach to prescribing medications for cirrhotic patients.

METHODS

An indexed MEDLINE search was conducted using keywords cirrhosis, drug-induced liver injury, pharmacodynamics (PDs), PKs, drug disposition and adverse drug reactions. Unpublished information from the Food and Drug Administration and industry was also reviewed.

RESULTS

Most medications have not been adequately studied in cirrhosis, and specific prescribing information is often lacking. Lower doses are generally recommended based on PK changes, but data are limited in terms of correlating PD effects with the degree of liver impairment. Very few drugs have been documented to have their hepatotoxicity potential enhanced by cirrhosis; most of these involve antituberculosis or antiretroviral agents used for HIV or viral hepatitis. Paracetamol can be used safely when prescribed in relatively small doses (2-3 g or less/day) for short durations, and is recommended as first-line treatment of pain. In contrast, NSAIDs should be used cautiously (or not at all) in advanced cirrhosis. Proton pump inhibitors have been linked to an increased risk of spontaneous bacterial peritonitis (SBP) in cirrhosis and should be used with care.

CONCLUSIONS

Most drugs can be used safely in cirrhosis, including those that are potentially hepatotoxic, but lower doses or reduced dosing frequency is often recommended, due to altered PKs. Drugs that can precipitate renal failure, gastrointestinal bleeding, SBP and encephalopathy should be identified and avoided.

Oral ingestion of a topical benzydamine hydrochloride-containing gynaecological preparation in association with television advertising in Italy: analysis of cases managed by a National Poison Control Centre

Objective To evaluate the impact of a television advertising campaign on the risk of oral ingestion of a topical non-prescription gynaecological preparation containing benzydamine hydrochloride. Design An interrupted time series design with data routinely collected. Setting A National Poison Control Centre. Participants 215 cases of hazardous exposure to the preparation under study occurred in Italy from January 2005 to December 2010. Primary and secondary outcome measures Mean daily rate of cases of exposure by gender in three different periods, that is, pre-advertisement period, before the advertisement was broadcast (from 1 January 2005 to 19 December 2009), advertisement period, when the advertisement was repeatedly launched (from 20 December 2009 to 27 February 2010), post-advertisement period (from 28 February 2010 to 6 March 2010); observed/expected ratios of cases, with expected cases based on data from the pre-advertisement period, adjusted for estimated variations in the number of users. Comparison of the distribution of the main characteristics of cases in the three different periods by means of Pearson's χ(2) test or Fisher's exact test. Results The adjusted observed/expected ratio of cases in women was 7.48 (95% CI 5.76 to 9.56) in the advertisement period and 2.97 (95% CI 2.24 to 3.85) in the post-advertisement period. Regarding the characteristics of cases, there was an increased proportion of cases of exposure due to confusion about the correct administration route in the advertisement and post-advertisement periods (81% and 55%, respectively, compared to 16% for the pre-advertisement period.) and of individuals with clinical effects (55%, 52% and 27%, respectively). Conclusions In Italy, an advertisement for a non-prescription medicine seems to have confused consumers regarding the administration route. This effect was observed even after the advertisement had stopped being broadcast. These results highlight the need for the monitoring of medication errors and adverse effects before, during and after advertising.

Understanding lactic acidosis in paracetamol (acetaminophen) poisoning

Paracetamol (acetaminophen) is one of the most commonly taken drugs in overdose in many areas of the world, and the most common cause of acute liver failure in both the UK and USA. Paracetamol poisoning can result in lactic acidosis in two different scenarios. First, early in the course of poisoning and before the onset of hepatotoxicity in patients with massive ingestion; a lactic acidosis is usually associated with coma. Experimental evidence from studies in whole animals, perfused liver slices and cell cultures has shown that the toxic metabolite of paracetamol, N-acetyl-p-benzo-quinone imine, inhibits electron transfer in the mitochondrial respiratory chain and thus inhibits aerobic respiration. This occurs only at very high concentrations of paracetamol, and precedes cellular injury by several hours. The second scenario in which lactic acidosis can occur is later in the course of paracetamol poisoning as a consequence of established liver failure. In these patients lactate is elevated primarily because of reduced hepatic clearance, but in shocked patients there may also be a contribution of peripheral anaerobic respiration because of tissue hypoperfusion. In patients admitted to a liver unit with paracetamol hepatotoxicity, the post-resuscitation arterial lactate concentration has been shown to be a strong predictor of mortality, and is included in the modified King's College criteria for consideration of liver transplantation. We would therefore recommend that post-resuscitation lactate is measured in all patients with a severe paracetamol overdose resulting in either reduced conscious level or hepatic failure.

Paracetamol metabolism and related genetic differences

Paracetamol (acetaminophen) is a worldwide used analgesic and antipyretic drug. It is metabolised via several metabolic pathways, including glucuronidation, sulfation, oxidation, hydroxylation, and deacetylation: Hepatic and other organ damage may occur, especially in overdose, because of the accumulation of a toxic metabolite. Intersubject and ethnic differences have been reported in paracetamol metabolism activation, suggesting possible differences in susceptibility to toxicity and in pain alleviation, linked to different pharmacogenetic profiles. This article aims at reviewing, in the literature, the links between paracetamol metabolism and enzyme genotypes in the context of toxic side effects and efficacy of paracetamol in therapeutics.

Overexpression of cyclooxygenase-2 in rat oral cancers and prevention of oral carcinogenesis in rats by selective and nonselective COX inhibitors

Oral squamous cell carcinomas induced in rats by 4-nitroquinoline-1-oxide (NQO) show substantial overexpression of cyclooxygenase-2 (COX-2) when compared with adjacent phenotypically normal oral tissues. By contrast, neither 5-lipoxygenase (LOX) nor 12-LOX is overexpressed in rat oral cancers. Two chemoprevention studies were done to test the resulting hypothesis that COX-2 is a useful target for oral cancer chemoprevention in the rat. In both studies, male F344 rats received drinking water exposure to NQO (20 ppm) for 10 weeks, followed by administration of chemopreventive agents from week 10 until study termination at week 26. In the first study, groups of rats were fed basal diet (control), or basal diet supplemented with the selective COX-2 inhibitor celecoxib (500 or 1,500 mg/kg diet), the nonselective COX inhibitor piroxicam (50 or 150 mg/kg diet), or the 5-LOX inhibitor zileuton (2,000 mg/kg diet). In the second study, rats were fed basal diet (control) or basal diet supplemented with nitric oxide-naproxen (180 or 90 mg/kg diet), a nonselective COX inhibitor that shows reduced gastrointestinal toxicity. When compared with dietary controls, celecoxib decreased oral cancer incidence, cancer invasion score, and cancer-related mortality. Piroxicam decreased cancer-related mortality and cancer invasion score, whereas nitric oxide-naproxen decreased oral cancer incidence and cancer invasion score. By contrast, zileuton showed no chemopreventive activity by any parameter assessed. These data show that both selective and nonselective inhibitors of COX-2 can prevent NQO-induced oral carcinogenesis in rats. The chemopreventive activity of COX inhibitors may be linked to overexpression of their enzymatic target in incipient oral neoplasms.

Impact of bilingual product information labels on Spanish-speaking adults' ability to comprehend OTC information

BACKGROUND

There is a steady growth in the Spanish-speaking population in the United States. Language may be a barrier in accessing nonprescription medication information for the non-English-speaking population.

OBJECTIVE

The objective of this study was to compare consumer-reported ease of use, product knowledge, and intention to purchase over-the-counter (OTC) medications using bilingual Product Information Labels (PILs) and currently available label formats in a sample of Spanish-speaking consumers.

METHODS

Participants were randomly selected from Spanish-speaking consumers shopping for OTC medications in pharmacy or grocery stores in Houston, TX. Participants viewed 3 label formats (old, new, and PILs) for acetaminophen, ibuprofen, and aspirin in a random order. Questionnaires in English and in Spanish were provided to consumers after they viewed each label format. Domains measured in the questionnaires included ease of use, product knowledge, and purchase intention. All responses were measured on a 7-point Likert-type scale. Data were recoded and analyzed using SAS (version 9.0) (SAS Institute Inc, Cary, NC) to obtain mean scores for each domain. Participants were classified according to language proficiency into "Spanish only" and bilinguals. Comparative statistics were computed to compare mean scores between label formats in each consumer category.

RESULTS

A total of 225 questionnaires were collected. The mean (+/-standard deviation) age of participants was 38.91 (+/-11.95) years. A majority of respondents were Hispanic (97.75%), female (60.54%), and married (62.44%). Mean scores from viewing PILs on ease of use, product knowledge, and purchase intention were higher than those from viewing the other label formats. In the category of consumers who spoke Spanish only, mean scores of PILs were significantly higher as compared to those of old and new label formats (P<.05).

CONCLUSION

Information provided in Spanish on PILs may be very helpful to the Spanish-speaking community when selecting nonprescription medications. Policy makers and health care providers should consider PILs as an effective means of reducing language barriers and providing OTC medication information to the Spanish-speaking population in the United States.

Paracetamol (acetaminophen) pack size restrictions and poisoning severity: time trends in enquiries to a UK poisons centre

BACKGROUND AND OBJECTIVE

In September 1998, legislation was introduced in the United Kingdom to limit paracetamol pack sizes to 16 tablets of 500 mg at general sales outlets and 32 tablets of 500 mg at pharmacies. The effect of the regulations on severity of paracetamol poisoning is unclear. The aim of this study was to describe trends in the severity of paracetamol poisoning and to assess the impact of the 1998 Regulations on the enquiries to a UK poisons centre.

METHODS

We extracted data about the age, sex and number of tablets or capsules of paracetamol ingested by patients notified to Guy's and St Thomas' Poisons Unit (London, UK) between 1996 and 2004.

RESULTS AND DISCUSSION

During the study period, there were approximately 140 000 patients with suspected paracetamol poisoning, accounting for around 11% of all patients reported to the poisons unit. The median number of tablets fell from 25 to 20 for males and 20 to 16 for females after 1998. There was also a reduction in the proportion of patients who ingested 17-32 tablets (from 36% to 30%) and 33-100 tablets (from 25% to 19%).

CONCLUSION

Following the 1998 Regulations there was a decline in the severity, but not frequency, of paracetamol poisoning cases reported to Guy's and St Thomas' Poisons Unit. It is unclear whether the decline in severity was a direct consequence of the regulations.

A retrospective evaluation of analgesic exposures from Izmir, Turkey

The objective of this study is to analyze exposures concerning analgesics that were reported to Dokuz Eylul University Drug and Poison Information Center (DPIC) and admitted to the Department of Emergency Medicine in Dokuz Eylul University Hospital (EMDEU) between 1993 and 2004. Demographics of the patients, characteristics of analgesic exposures, performed treatment attempts and outcome of the poisoned patients were recorded on standard data forms and were then entered into a computerized database program. Statistical analysis was performed by using the chi-square test. The DPIC recorded 55 962 poisoning calls, 48 654 (86.9%) of them related to medicines. Analgesics accounted for 16.3% (7 939 cases) of all medicine-related exposures; among them 446 exposures were admitted to EMDEU. More than half of the analgesic exposure calls and admitted cases involved adults (55.9%, 4 440). Females dominated in all age groups (70.3%, 5 578). Mean age was 20.2 +/- 11.8. The most involved analgesics were paracetamol (47.9%), propionic acid derivatives (16.1%) and salicylates (13.7%). Most of the poisonings were intentional (75.1%), especially in 19-29 years age group of adults and 13-18 years age group of children. Most of the patients reported to DPIC and admitted to EMDEU were asymptomatic (84.4% and 54.7%, respectively). Gastrointestinal decontamination methods were performed more frequently for admitted poisoning cases before hospital admission than reported poisoning cases (61% vs. 23%). Paracetamol ingestion was the most common cause of analgesic exposures reported to our DPIC. Most of the analgesic exposures reported to DPIC were asymptomatic or mild. DPICs have an important role for the referral of analgesic exposures without unnecessary gastrointestinal decontamination procedures.

Nonsteroidal anti-inflammatory drug-induced hepatotoxicity

Nonsteroidal anti-inflammatory drugs are among the most common drugs associated with drug-induced liver injury, with an estimated incidence of between 3 and 23 per 100,000 patient years. Nimesulide, sulindac, and diclofenac seem to be associated with the highest risk and the only risk factor consistently identified is the concomitant use of other hepatotoxic drugs. Diclofenac-induced liver injury is a paradigm for drug-related hepatotoxicity. Recent studies suggest that genetic factors favoring the formation and accumulation of the reactive acylglucuronide metabolite of diclofenac and an enhanced immune response to the metabolite-protein adducts are associated with increased susceptibility to hepatotoxicity.

Emergency department management of the salicylate-poisoned patient

Salicylate toxicity continues to be encountered commonly in emergency medicine. This article portrays the signs and symptoms of salicylate toxicity, reviews the erratic absorption and elimination kinetics, describes the devastating physiologic effects of overdose, and illustrates the potentially subtle manifestations of chronic aspirin toxicity.

Drug bioactivation, covalent binding to target proteins and toxicity relevance

A number of therapeutic drugs with different structures and mechanisms of action have been reported to undergo metabolic activation by Phase I or Phase II drug-metabolizing enzymes. The bioactivation gives rise to reactive metabolites/intermediates, which readily confer covalent binding to various target proteins by nucleophilic substitution and/or Schiff's base mechanism. These drugs include analgesics (e.g., acetaminophen), antibacterial agents (e.g., sulfonamides and macrolide antibiotics), anticancer drugs (e.g., irinotecan), antiepileptic drugs (e.g., carbamazepine), anti-HIV agents (e.g., ritonavir), antipsychotics (e.g., clozapine), cardiovascular drugs (e.g., procainamide and hydralazine), immunosupressants (e.g., cyclosporine A), inhalational anesthetics (e.g., halothane), nonsteroidal anti-inflammatory drugs (NSAIDSs) (e.g., diclofenac), and steroids and their receptor modulators (e.g., estrogens and tamoxifen). Some herbal and dietary constituents are also bioactivated to reactive metabolites capable of binding covalently and inactivating cytochrome P450s (CYPs). A number of important target proteins of drugs have been identified by mass spectrometric techniques and proteomic approaches. The covalent binding and formation of drug-protein adducts are generally considered to be related to drug toxicity, and selective protein covalent binding by drug metabolites may lead to selective organ toxicity. However, the mechanisms involved in the protein adduct-induced toxicity are largely undefined, although it has been suggested that drug-protein adducts may cause toxicity either through impairing physiological functions of the modified proteins or through immune-mediated mechanisms. In addition, mechanism-based inhibition of CYPs may result in toxic drug-drug interactions. The clinical consequences of drug bioactivation and covalent binding to proteins are unpredictable, depending on many factors that are associated with the administered drugs and patients. Further studies using proteomic and genomic approaches with high throughput capacity are needed to identify the protein targets of reactive drug metabolites, and to elucidate the structure-activity relationships of drug's covalent binding to proteins and their clinical outcomes.

Selecting nonprescription analgesics

Worldwide, there has been an emerging patient demand for access to efficient drugs without consulting a doctor and obtaining a prescription. As a result, there has been an expanding movement of prescription-only drugs to over-the-counter (OTC) status. An increasing number of drugs are becoming available OTC, empowering patients to treat themselves. Where the principle of empowering individuals to treat themselves can fail is when consumers lack the knowledge to do so safely. This potentially applies to the self-selection of analgesic drugs by consumers. When used inappropriately, these drugs pose significant risks. The nonsteroidal antiinflammatory drugs (NSAIDs) are associated with many adverse reactions, interactions, and contraindications in a number of patient groups, even at OTC doses. In particular, in the elderly, the high incidence of cardiovascular and gastrointestinal disease, coupled with age-related decline in renal function and multiple medication use, all warrant extra caution with the use of NSAIDs and make paracetamol the simple analgesic drug of first choice. Despite the possibility of hepatotoxicity in overdose, paracetamol represents a better all-round option for most patients requiring OTC analgesic therapy.

The Therapeutic Use of Acetaminophen in Patients with Liver Disease

Acetaminophen has been used safely and effectively for many years to manage pain and/or fever in patients of all ages. It is commonly recommended as first-line therapy for a variety of patients and conditions, including the elderly, children with viral illnesses, and patients with osteoarthritis, gastrointestinal conditions, bleeding disorders, cardiovascular disease, or renal disease. However, its use is often avoided in patients with chronic liver disease. The perception that acetaminophen should be avoided in such patients arose from awareness of the association between massive acetaminophen overdose and hepatotoxicity, combined with a lack of understanding of the metabolism of acetaminophen in patients with liver disease. There are various theoretical mechanisms of acetaminophen hepatotoxicity in chronic liver disease including: altered metabolism and depleted glutathione stores that would be expected to increase accumulation of the hepatotoxic intermediate, N-acetyl-p-benzoquinone imine (NAPQI). Available studies in patients with chronic liver disease, however, have shown that although the half-life of acetaminophen may be prolonged, cytochrome P-450 activity is not increased and glutathione stores are not depleted to critical levels in those taking recommended doses. Furthermore, acetaminophen has been studied in a variety of liver diseases without evidence of increased risk of hepatotoxicity at currently recommended doses. Therefore, acetaminophen can be used safely in patients with liver disease and is a preferred analgesic/antipyretic because of the absence of the platelet impairment, gastrointestinal toxicity, and nephrotoxicity associated with nonsteroidal antiinflammatory drugs.

Thyroid storm induced by aspirin intoxication and the effect of hemodialysis: a case report

Thyroid dysfunction is one of the serious consequences of an overdose of acetaminophen, aspirin, or nonsteroidal antiinflammatory drugs. The management of such consequences remains a medical challenge. A variety of thyroid abnormalities are common in clinical practice and can, in many cases, be accurately diagnosed and managed by the primary care physician. This case study covers an aspirin overdose causing thyroid storm that was treated successfully with hemodialysis.

Drug interactions in dentistry

BACKGROUND

The hepatic and intestinal cytochrome, or CY, P450 enzyme system is responsible for the biotransformation of a multitude of drugs. Certain medications used in dentistry can act as substrates, inducers or inhibitors of this system.

METHODS

The authors conducted a MEDLINE search of articles appearing between 1976 and the present using the keywords "drug interactions" and "cytochrome P450," and reviewed reports involving dental therapeutic agents using PubMed links from an Indiana University CYP450 drug interaction table on the World Wide Web.

RESULTS

The antibiotics erythromycin and clarithromycin are potent inhibitors of CYP3A4 and can increase blood levels and toxicity of CYP3A4 substrates. Likewise, quinolone antibiotics such as ciprofloxacin inhibit the metabolism of CYP1A2 substrates. Other dental therapeutic agents are substrates for CYP2C9 (celecoxib, ibuprofen and naproxen), CYP2D6 (codeine and tramadol), CYP3A4 (methylprednisolone) and CYP2E1 (acetaminophen). Because codeine and tramadol are prodrugs, inhibition of their metabolism can lead to a diminution of their analgesic effects. While inducers of acetaminophen metabolism, including alcohol, theoretically can increase the proportion of it that is biotransformed into a potentially hepatotoxic metabolite, recent research suggests that concomitant alcohol intake does not increase the hepatotoxic potential of therapeutic doses of acetaminophen.

CONCLUSIONS

A number of clinically significant drug interactions can arise with dental therapeutic agents that act as substrates or inhibitors of the CYP450 system. Clinical Implications. As polypharmacy continues to increase, the likelihood of adverse drug interactions in dentistry will increase as well. Ensuring that patients' medical histories are up to date and acquiring knowledge of the various substrates, inducers and inhibitors of the CYP450 system will help practitioners avoid potentially serious adverse drug interactions.

Separation and detection methods for covalent drug–protein adducts

Covalent binding of reactive metabolites of drugs to proteins has been a predominant hypothesis for the mechanism of toxicity caused by numerous drugs. The development of efficient and sensitive analytical methods for the separation, identification, quantification of drug-protein adducts have important clinical and toxicological implications. In the last few decades, continuous progress in analytical methodology has been achieved with substantial increase in the number of new, more specific and more sensitive methods for drug-protein adducts. The methods used for drug-protein adduct studies include those for separation and for subsequent detection and identification. Various chromatographic (e.g., affinity chromatography, ion-exchange chromatography, and high-performance liquid chromatography) and electrophoretic techniques [e.g., sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional SDS-PAGE, and capillary electrophoresis], used alone or in combination, offer an opportunity to purify proteins adducted by reactive drug metabolites. Conventionally, mass spectrometric (MS), nuclear magnetic resonance, and immunological and radioisotope methods are used to detect and identify protein targets for reactive drug metabolites. However, these methods are labor-intensive, and have provided very limited sequence information on the target proteins adducted, and thus the identities of the protein targets are usually unknown. Moreover, the antibody-based methods are limited by the availability, quality, and specificity of antibodies to protein adducts, which greatly hindered the identification of specific protein targets of drugs and their clinical applications. Recently, the use of powerful MS technologies (e.g., matrix-assisted laser desorption/ionization time-of-flight) together with analytical proteomics have enabled one to separate, identify unknown protein adducts, and establish the sequence context of specific adducts by offering the opportunity to search for adducts in proteomes containing a large number of proteins with protein adducts and unmodified proteins. The present review highlights the separation and detection technologies for drug-protein adducts, with an emphasis on methodology, advantages and limitations to these techniques. Furthermore, a brief discussion of the application of these techniques to individual drugs and their target proteins will be outlined.

Management of paracetamol poisoning

Paracetamol is the most common substance involved in self-poisoning in the UK. The main advances made over the past five years in the management of early paracetamol poisoning, identification of risk factors for paracetamol poisoning, understanding of the mechanisms and management of late paracetamol poisoning and issues concerning the prevention of paracetamol poisoning are discussed.