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Sandra R Knowles

Publications and source records attributed to Sandra R Knowles.

At least 19 recordsLinked to original sources
PubMed2006

Povidone-iodine-induced burn: case report and review of the literature.

Burns are a rare but potentially serious complication of povidone-iodine use. This rare adverse drug reaction developed in a 38-year-old woman who underwent laparoscopic right ovarian cystectomy and endometrial ablation as a day procedure involving application of the topical antiseptic 10% povidone-iodine solution. Two days later, the patient was admitted to the hospital with burning, pain, itching, marked redness, and blistering extending from her midback to buttocks. A stain on her back also was evident. Partial-thickness chemical burn was diagnosed. Review of the literature yielded 13 other cases of povidone-iodine-induced burn. This underrecognized adverse effect of povidone-iodine application typically occurs when the povidone-iodine has not been allowed to dry or has been trapped under the body of a patient in a pooled dependent position. The burn is usually seen immediately after the procedure or on the next day, and typically heals with minimum scarring within 3-4 weeks with conservative treatment. The commonly postulated mechanism is a chemical burn due to irritation coupled with maceration, friction, and pressure. Given the widespread use of povidone-iodine and the potential for development of infection after a burn, clinicians need to be aware of this possible povidone-iodine-associated adverse drug reaction, and of preventive measures.

Adult↗
PubMed2005

Frequency, type and clinical importance of medication history errors at admission to hospital: a systematic review.

BACKGROUND: Over a quarter of hospital prescribing errors are attributable to incomplete medication histories being obtained at the time of admission. We undertook a systematic review of studies describing the frequency, type and clinical importance of medication history errors at hospital admission. METHODS: We searched MEDLINE, EMBASE and CINAHL for articles published from 1966 through April 2005 and bibliographies of papers subsequently retrieved from the search. We reviewed all published studies with quantitative results that compared prescription medication histories obtained by physicians at the time of hospital admission with comprehensive medication histories. Three reviewers independently abstracted data on methodologic features and results. RESULTS: We identified 22 studies involving a total of 3755 patients (range 33-1053, median 104). Errors in prescription medication histories occurred in up to 67% of cases: 10%- 61% had at least 1 omission error (deletion of a drug used before admission), and 13%- 22% had at least 1 commission error (addition of a drug not used before admission); 60%- 67% had at least 1 omission or commission error. Only 5 studies (n = 545 patients) explicitly distinguished between unintentional discrepancies and intentional therapeutic changes through discussions with ordering physicians. These studies found that 27%- 54% of patients had at least 1 medication history error and that 19%- 75% of the discrepancies were unintentional. In 6 of the studies (n = 588 patients), the investigators estimated that 11%-59% of the medication history errors were clinically important. INTERPRETATION: Medication history errors at the time of hospital admission are common and potentially clinically important. Improved physician training, accessible community pharmacy databases and closer teamwork between patients, physicians and pharmacists could reduce the frequency of these errors.

Drug Prescriptions↗
PubMed2005

Clinical and immunogenetic correlates of abacavir hypersensitivity.

A patch test (PT) may be useful in defining true abacavir hypersensitivity syndrome (AHS). Seven previously PT-positive patients remote from the original AHS were shown to have robust 24 h responses, supporting PT durability. HLA-B*5701 was present in all seven PT-positive versus one of 11 controls tolerating abacavir (P < 0.001). Five of seven PT (71%) versus one of 11 controls (9%) (P = 0.005) showed significant abacavir-specific CD8 proliferation, suggesting a direct role for HLA-B*5701-restricted CD8 cells in the pathophysiology of AHS.

Anti-HIV Agents↗
PubMed2005

Unintended medication discrepancies at the time of hospital admission.

BACKGROUND: Prior studies suggest that unintended medication discrepancies that represent errors are common at the time of hospital admission. These errors are particularly worthy of attention because they are not likely to be detected by computerized physician order entry systems. METHODS: We prospectively studied patients reporting the use of at least 4 regular prescription medications who were admitted to general internal medicine clinical teaching units. The primary outcome was unintended discrepancies (errors) between the physicians' admission medication orders and a comprehensive medication history obtained through interview. We also evaluated the potential seriousness of these discrepancies. All discrepancies were reviewed with the medical team to determine if they were intentional or unintentional. All unintended discrepancies were rated for their potential to cause patient harm. RESULTS: After screening 523 admissions, 151 patients were enrolled based on the inclusion criteria. Eighty-one patients (53.6%; 95% confidence interval, 45.7%-61.6%) had at least 1 unintended discrepancy. The most common error (46.4%) was omission of a regularly used medication. Most (61.4%) of the discrepancies were judged to have no potential to cause serious harm. However, 38.6% of the discrepancies had the potential to cause moderate to severe discomfort or clinical deterioration. CONCLUSIONS: Medication errors at the time of hospital admission are common, and some have the potential to cause harm. Better methods of ensuring an accurate medication history at the time of hospital admission are needed.

Aged↗
PubMed2005

Clindamycin skin testing has limited diagnostic potential.

We examined the role of clindamycin prick and intradermal skin testing in a tertiary care clinic population. Experience with diagnostic modalities such as prick and intradermal testing has been limited with clindamycin. A retrospective chart review was conducted for patients with immunologic reactions temporally associated with clindamycin who were referred to the Drug Safety Clinic (Toronto, Ontario). A total of 31 patients were identified who had undergone prick and intradermal skin testing. All 31 negative immediate prick and intradermal tests were followed by a 150 mg oral dose of clindamycin. 10/31 (32%) subjects had significant reactions to the oral clindamycin provocation. 2 patients reported delayed reactions at the clindamycin intradermal test sites. Our experience suggests that prick and intradermal skin testing is not adequate in identifying patients with previous allergic reactions associated with clindamycin. Oral provocation tests can be used in patients with histories of clindamycin adverse reactions; however, it should be offered on a risk-benefit basis.

Administration, Oral↗
PubMed2005

Hydrochlorothiazide-induced noncardiogenic pulmonary edema: an underrecognized yet serious adverse drug reaction.

Noncardiogenic pulmonary edema is a rare but potentially life-threatening complication of hydrochlorothiazide therapy. We describe three patients who developed this serious adverse reaction. A 64-year-old woman developed dypsnea and hypotension within 60 minutes of taking a single dose of hydrochlorothiazide 25 mg. She was admitted to the critical care unit with acute respiratory failure and subsequent multiple-organ dysfunction. The second patient was a 56-year-old woman who experienced sudden onset of shortness of breath that developed 10 minutes after taking a single dose of hydrochlorothiazide 25 mg. The third was a 59-year-old woman who developed sudden onset of shortness of breath, nausea, vomiting, and diarrhea after her first dose of hydrochlorothiazide-triamterene. All three women had a history of a similar, albeit minor, reaction to a thiazide diuretic. Review of the literature identified 36 additional cases of noncardiogenic pulmonary edema after thiazide use. The patients developed symptoms 10-150 minutes after ingestion of hydrochlorothiazide or another thiazide. Symptoms can occur on first exposure to the drug or in patients taking the drug intermittently. Of interest, 90% of documented cases occurred in women. With the increasing use of thiazide diuretics in the treatment of hypertension, clinicians need to be aware of the possible association of these drugs with the development of noncardiogenic pulmonary edema.

Diuretics↗
PubMed2004

Objective psychological measurement and clinical assessment of anxiety in adverse drug reactions.

BACKGROUND: A confounding factor in the diagnosis of adverse drug reactions (ADRs) is the psychological state of the patient. Patients with underlying anxiety and related disorders may present with psychogenic reactions, which involve physiologic responses originating from psychological, rather than organic factors. OBJECTIVE: To examine the contribution of anxiety and related disorders to adverse drug events. METHODS: Participants from an adverse drug reaction clinic completed the Trauma Symptom Checklist-40 (TSC-40), a 40-item questionnaire consisting of six subscales: anxiety, depression, dissociation, sexual abuse trauma index (SATI), sexual problems, and sleep disturbance. Physicians assessed the likelihood that adverse events were due to anxiety or drug(s) by providing an anxiety score (0 to 10) and an ADR score (0 to 10), respectively, for each participant. RESULTS: Patients clinically assessed as having "high anxiety" (anxiety score 7-10 and ADR score 0-3; n = 11) scored higher than patients clinically assessed as having a "true ADR" (anxiety score 0-3 and ADR score 7-10; n = 19) on the TSC-40 total (P = 0.006) as well as anxiety (P = 0.012), depression (P = 0.007), and SATI subscales (P = 0.016). CONCLUSION: This study is the first to use a validated psychological measurement to indicate that a substantial percentage of reported adverse drug events may in fact be a manifestation of underlying anxiety and/or related disorders. We suggest that mechanisms of symptom generation may be analogous to those operative in idiopathic environmental intolerance.

Adolescent↗
PubMed2004

Evaluation of the extent of under-reporting of serious adverse drug reactions: the case of toxic epidermal necrolysis.

INTRODUCTION: Toxic epidermal necrolysis (TEN) is a life-threatening adverse drug reaction (ADR) that is primarily the result of drug exposure (incidence 0.4-1.3 per million person-years). Life-threatening ADRs such as TEN should be reported to ADR monitoring programmes, which collect reports for suspected ADRs and alert the public and medical practitioners to new drug hazards. In Canada, reports are made to the Canadian Adverse Drug Reaction Monitoring Program (CADRMP). OBJECTIVE: To examine the extent of under-reporting for TEN in Canada. DESIGN: A retrospective case series design was used to collect all TEN cases for the period January 1995 to December 2000. METHODS: The CADRMP and 22 burn centres across Canada were contacted for all TEN patients treated during the specified time period. PATIENT GROUPS STUDIED: The study population consisted of patients admitted to burn treatment sites across Canada, patient cases reported to the CADRMP and patient cases recorded by the Canadian Institute for Health Information (CIHI) hospital discharge summaries as the International Classification of Diseases Version 9 Clinical Modification (ICD-9-CM) code 695.1. RESULTS: Twenty-five TEN cases (six fatal) were reported to CADRMP from January 1995 to December 2000. During this period, 14 (63.6%) burn treatment sites reported admission of 250 TEN cases. Hospital discharge summaries using the ICD-9-CM code 695.1 indicated that 4349 cases were admitted to hospital during this time period and it was estimated that 15.5% (n = 674) of these cases were TEN. Using the burn facility data as the denominator, 10% (25 of 250) of TEN cases were reported to CADRMP. Using CIHI data as a denominator, only 4% (25 of 674) of TEN cases were reported to CADRMP. CONCLUSIONS: There is serious under-reporting of TEN. Lack of reporting of life-threatening ADRs can compromise population safety. There is a need to increase awareness of ADR reporting programmes.

Adverse Drug Reaction Reporting Systems↗
PubMed2003

Common adverse events associated with the use of ribavirin for severe acute respiratory syndrome in Canada.

Although information on efficacy and adverse drug reactions is lacking, ribavirin has been used empirically for the treatment of severe acute respiratory syndrome (SARS). We report common adverse events in 110 patients with suspected or probable SARS who were treated with ribavirin. Sixty-one percent of the patients had evidence of hemolytic anemia, and hypocalcemia and hypomagnesmia were reported in 58% and 46% of patients, respectively.

Adolescent↗
PubMed2003

Reactive metabolites and adverse drug reactions: clinical considerations.

Idiosyncratic reactions can affect many different organ systems, either as -an isolated event (e.g., hepatitis) or as part of a syndrome (e.g., drug hypersensitivity syndrome). Formation of reactive metabolites of drugs in conjunction with a decreased ability for detoxification is believed to be the initiating step in many idiosyncratic reactions. The drug hypersensitivity syndrome, defined by the presence of fever, rash and internal organ involvement, is estimated to occur in approx 1 in 1000 to 1 in 10,000 exposures with drugs such as anticonvulsants sulfonamide antibiotics, allopurinol, and dapsone. Symptoms usually start within 2-8 wk of drug initiation. Serum sicknesslike reaction, most frequently found after 7-14 d of drug exposure, is distinguished by a fever, cutaneous eruption and arthralgias. Medications such as cefaclor, minocycline and bupropion are most frequently implicated in this reaction. In contrast, drug-induced lupus can occur l-2 yr after initiation of medication. Drug-induced lupus is characterized by musculoskeletal complaints and fever and weight loss. Drugs most commonly associated with drug-induced lupus include procainamide, hydralazine, chlorpromazine, isoniazid, and minocycline. Management of patients who develop idiosyncratic reactions includes discontinuation of the implicated drug, initiation of corticosteroids (when appropriate), and symptomatic relief as required. Internal organ involvement, which may initially be asymptomatic, should be monitored. Confirmatory or diagnostic tests are not readily available in most areas, except for research purposes.

Drug Hypersensitivity↗
PubMed2003

Safety of celecoxib in individuals allergic to sulfonamide: a pilot study.

OBJECTIVE: To evaluate cross reactivity between sulfonamide antimicrobials and celecoxib in patients with histories of allergies to sulfonamide antimicrobials. METHODS: Immunocompetent patients with a history of sulfonamide antimicrobial allergy who were being considered for therapy with celecoxib were prospectively enrolled. Sulfamethoxazole and trimethoprim skin prick and intradermal testing and/or an in vitro lymphocyte toxicity assay were performed. If skin testing was negative, an oral challenge with sulfamethoxazole and trimethoprim was performed. Oral challenges with celecoxib were administered to all patients. RESULTS: Twenty-eight immunocompetent patients (26 female; mean age 60 years) were evaluated. History of sulfonamide antimicrobial allergy included urticaria (n = 7), cutaneous eruptions (n = 9), and other (n = 12). Four of the 28 patients who were skin prick tested were positive to sulfamethoxazole and two of the ten patients who underwent in vitro testing were positive to sulfamethoxazole. All 28 patients were administered celecoxib and tolerated the medication. Phone call follow up in 25 patients disclosed that 15 patients continued to take celecoxib, while five patients did not take celecoxib following the oral challenge, and five discontinued celecoxib due to adverse effects, lack of drug efficacy or physician preference. CONCLUSIONS: Confusion exists regarding the potential for cross reactivity between sulfonamide antimicrobials and other sulfonamide-containing compounds. The six sulfonamide-allergic patients tolerated celecoxib uneventfully. This pilot study supports the hypothesis that the potential for cross-reactivity between celecoxib and sulfonamide antimicrobials appears to be low. However, further investigations are required to confirm this.

Administration, Oral↗