QT time prolongation
Adverse drug events
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Explanations of the substances for patients
We have no additional warnings for the combination of astemizole and buprenorphine. Please also consult the relevant specialist information.
The reported changes in exposure correspond to the changes in the plasma concentration-time curve [ AUC ]. We do not expect any change in exposure for astemizole, when combined with buprenorphine (100%). We did not detect any change in exposure to buprenorphine. We currently cannot estimate the influence of astemizole.
The pharmacokinetic parameters of the average population are used as the starting point for calculating the individual changes in exposure due to the interactions.
Astemizole has a low oral bioavailability [ F ] of 3%, which is why the maximum plasma level [Cmax] tends to change strongly with an interaction. The terminal half-life [ t12 ] is 22 hours and constant plasma levels [ Css ] are reached after approximately 88 hours. The protein binding [ Pb ] is 97% strong. The metabolism takes place via CYP2D6 and CYP3A4, among others.
Buprenorphine has a low oral bioavailability [ F ] of 10%, which is why the maximum plasma level [Cmax] tends to change strongly with an interaction. The terminal half-life [ t12 ] is rather short at 3.2 hours and constant plasma levels [ Css ] are reached quickly. The protein binding [ Pb ] is 96% strong and the volume of distribution [ Vd ] is very large at 335 liters, The metabolism mainly takes place via CYP3A4.
|Serotonergic Effects a||1||Ø||+|
Recommendation: As a precautionary measure, symptoms of serotonergic overstimulation should be taken into account, especially after increasing the dose and at doses in the upper therapeutic range.
Rating: Buprenorphine has a mild effect on the serotonergic system. The risk of a serotonergic syndrome can be classified as low with this medication if the dosage is in the usual range. According to our knowledge, astemizole does not increase serotonergic activity.
|Kiesel & Durán b||0||Ø||Ø|
Rating: According to our knowledge, neither astemizole nor buprenorphine increase anticholinergic activity.
QT time prolongation
Rating: In combination, astemizole and buprenorphine can potentially trigger ventricular arrhythmias of the torsades de pointes type.
General adverse effects
|Side effects||∑ frequency||ast||bup|
Sedation (3.4%): buprenorphine
Cerebrovascular accident: buprenorphine
Bowel obstruction: buprenorphine
Upper respiratory infection: buprenorphine
Respiratory depression: buprenorphine
Respiratory failure: buprenorphine
Adrenal insufficiency: buprenorphine
Hepatic encephalopathy: buprenorphine
Hepatorenal syndrome: buprenorphine
Liver failure: buprenorphine
Hypersensitivity reaction: buprenorphine
Based on your answers and scientific information, we assess the individual risk of undesirable side effects. These recommendations are intended to advise professionals and are not a substitute for consultation with a doctor. In the restricted test version (alpha), the risk of all substances has not yet been conclusively assessed.
Abstract: The disposition of buprenorphine has been studied in two patient groups to assess the influence of impaired renal function on the metabolism of buprenorphine and two of its metabolites, buprenorphine-3-glucuronide (B3G) and norbuprenorphine (NorB). A single i.v. dose of 0.3 mg was given to 15 patients (nine with dialysis-dependent renal failure) undergoing lower abdominal or peripheral body surface surgery. Blood was sampled up to 24 h. Concentrations of buprenorphine, B3G and NorB were assayed by a differential radioimmunoassay technique. There were no differences in buprenorphine kinetics between anaesthetized healthy patients and those with renal impairment: mean elimination half-lives 398 and 239 min; clearance 651 and 988 ml min-1; apparent volume of distribution at steady state 313 and 201 litre, respectively. Both metabolites were undetectable following the single i.v. dose. In a second group of 20 patients (eight with renal impairment), buprenorphine was administered by continuous infusion for provision of analgesia and control of ventilation in the ITU (median infusion rate 161 micrograms h-1 (range 36-230 micrograms h-1) for a median duration of 30 h (2-565 h). Buprenorphine clearance in patients with normal and impaired renal function was similar (934 and 1102 ml min-1, respectively), as were dose-corrected plasma concentrations of buprenorphine. In patients with renal failure, plasma concentrations of NorB were increased by a median of four times, and B3G concentrations by a median of 15 times.
Abstract: The kinetics and systemic bioavailability of intranasally administered buprenorphine have been investigated in 9 healthy volunteers in an intranasal/intravenous cross-over study. Each subject received a nominal 0.3 mg dose of buprenorphine intranasally followed one week later by a matched dose intravenously. For the intranasal administration mean tmax and mean Cmax were 30.6 min and 1.77 ng mL-1, respectively. Mean intranasal bioavailability was 48.2 +/- 8.35% (mean +/- s.e.m.) of the intravenous value. Intranasal administration may represent a valuable new delivery route for buprenorphine.
Abstract: Astemizole is a long-acting, highly selective histamine1-receptor antagonist with minimal central and anticholinergic effects. Comparison studies have shown astemizole to be equal or superior to currently available antihistamines, beclomethasone nasal spray, and cromolyn sodium in relieving allergic symptoms of seasonal and perennial allergic rhinitis. Other uses include treatment of allergic conjunctivitis and chronic urticaria. Astemizole is not as effective for treatment of acute allergic symptoms because of its delayed onset of action. Astemizole and its active metabolite, desmethylastemizole, have long elimination half-lives permitting once-daily dosing. The incidence of sedation is lower than with conventional antihistamines, but increased appetite and weight gain do occur. Astemizole should be useful for both maintenance and prophylactic therapy in patients with chronic allergic conditions who cannot tolerate the sedative or anticholinergic effects of conventional antihistamines.
Abstract: Astemizole is an H1-histamine receptor antagonist with a long duration of action permitting once daily administration. Its efficacy in seasonal and perennial allergic rhinitis has been convincingly demonstrated, and several comparative studies suggest that astemizole is at least as effective as some other H1-histamine receptor antagonists. A few smaller studies have shown beneficial effects on the symptoms of allergic conjunctivitis and chronic urticaria (but not atopic dermatitis). While astemizole appears to share with other H1-histamine receptor antagonists a tendency to increase appetite and cause weight gain after prolonged use, it offers the important advantage of an absence of significant central nervous system depression or anticholinergic effects with usual doses. Thus, astemizole offers a worthwhile improvement in side effect profile over 'traditional' H1-histamine receptor antagonists, especially in patients bothered by the sedative effects of these drugs.
Abstract: An overdose of astemizole predisposes the myocardium to ventricular dysrhythmias, including torsades de pointes. Herein we describe a case of astemizole-induced torsades de pointes ventricular tachycardia and also review previous case reports in the literature. All the patients were young, and dysrhythmias developed only in those with corrected QT intervals greater than 500 ms. Although several mechanisms have been postulated, no clear explanation has been provided for why astemizole promotes myocardial dysrhythmias. Treatment of astemizole-induced torsades de pointes includes discontinuing use of astemizole, intravenous administration of magnesium sulfate and isoproterenol, temporary cardiac pacing, and, when necessary, direct current cardioversion. A cardiac cause of syncope or convulsions must not be overlooked, especially in patients taking H1 antagonists because they often have these symptoms before hospitalization or detection of torsades de pointes (or both).
Abstract: No Abstract available
Abstract: A 26 year-old woman was admitted to the hospital two hours after astemizole overdose. Electrocardiograph showed a prolonged QT interval. Torsade de pointes occurred 13 h after ingestion. Plasma levels of astemizole plus hydroxylated metabolites showed an apparent plasma half-life of 17 h. The possible occurrence of torsade de pointes in astemizole overdose, and the long elimination time of astemizole and hydroxylated metabolites, makes it necessary to maintain ECG monitoring until QT interval has returned to normal.
Abstract: Buprenorphine administered sublingually is a promising treatment for opiate dependence. Utilizing a new, sensitive, and specific gas chromatographic electron-capture detector assay, the absolute bioavailability of sublingual buprenorphine was determined in six healthy volunteers by comparing plasma concentrations after 3- and 5-minute exposures to 2 mg sublingual and 1 mg intravenous buprenorphine. The amount of unabsorbed buprenorphine in saliva was measured after 2-, 4-, and 10-minute exposures to 2 mg sublingual buprenorphine in 12 participants. Pharmacokinetic parameters were analyzed by analysis of variance; bioequivalence was evaluated by the Schuirmann two-sided test. The 3- and 5-minute sublingual exposures each allowed 29 +/- 10% bioavailability (area under the plasma concentration-time curve unextrapolated) and were bioequivalent. Buprenorphine recovered from saliva after 2-, 4-, and 10-minute exposures was, on average, 52% to 55% of dose. Increased saliva pH was correlated with decreased recovery from saliva. Study results indicate that bioavailability of sublingual buprenorphine is approximately 30%. Sublingual exposure times between 3 and 5 minutes produce equivalent results. Buprenorphine remaining in saliva causes an almost twofold overestimation of bioavailability.
Abstract: AIMS: The aim of this study was to investigate the influence of chronic itraconazole treatment on the pharmacokinetics and cardiovascular effects of single dose astemizole in healthy subjects was studied. METHODS: Twelve male volunteers were taking orally 200 mg twice daily itraconazole or placebo for 14 days with a washout period of 4 weeks in between. Approximately 2 h after the morning dose of itraconazole or placebo on day 11, 10 mg astemizole was orally administered. The plasma concentrations of astemizole and desmethylastemizole were measured by radioimmunoassay up to 504 h after administration; electrocardiograms with analysis of the QTc interval were recorded up to 24 h post administration. RESULTS: Itraconazole treatment did not significantly change the peak concentration of astemizole (0.74 vs 0.81 ng ml-1) but it increased the area under the curve from 0 to 24 h (5.46 to 9.95 ng ml-1 h) and from 0 to infinity (17.4 to 48.2 ng ml-1 h), and the elimination half-life (2.1 to 3.6 days). The systemic bioavailability of desmethylastemizole was also increased. The QTc interval did not increase after astemizole administration and there was no difference in the QTc intervals between the itraconazole and placebo session. CONCLUSIONS: Chronic administration of itraconazole influences the metabolism of single dose astemizole in normal volunteers without changes of cardiac repolarization during the first 24 h after astemizole administration. However, the reduction in astemizole clearance under concomitant administration of itraconazole may result in a marked increase in astemizole plasma concentrations and QTc alterations during chronic combined intake of astemizole with itraconazole.
Abstract: Second-generation histamine H1 receptor antagonists (antihistamines) have been developed to reduce or eliminate the sedation and anticholinergic adverse effects that occur with older H1 receptor antagonists. This article evaluates second-generation antihistamines, including acrivastine, astemizole, azelastine, cetirizine, ebastine, fexofenadine, ketotifen, loratadine, mizolastine and terfenadine, for significant features that affect choice. In addition to their primary mechanism of antagonising histamine at the H1 receptor, these agents may act on other mediators of the allergic reaction. However, the clinical significance of activity beyond that mediated by histamine H1 receptor antagonism has yet to be demonstrated. Most of the agents reviewed are metabolised by the liver to active metabolites that play a significant role in their effect. Conditions that result in accumulation of astemizole, ebastine and terfenadine may prolong the QT interval and result in torsade de pointes. The remaining agents reviewed do not appear to have this risk. For allergic rhinitis, all agents are effective and the choice should be based on other factors. For urticaria, cetirizine and mizolastine demonstrate superior suppression of wheal and flare at the dosages recommended by the manufacturer. For atopic dermatitis, as adjunctive therapy to reduce pruritus, cetirizine, ketotifen and loratadine demonstrate efficacy. Although current evidence does not suggest a primary role for these agents in the management of asthma, it does support their use for asthmatic patients when there is coexisting allergic rhinitis, dermatitis or urticaria.
Abstract: AIMS: The aims of the present study were to investigate the metabolism of astemizole in human liver microsomes, to assess possible pharmacokinetic drug-interactions with astemizole and to compare its metabolism with terfenadine, a typical H1 receptor antagonist known to be metabolized predominantly by CYP3A4. METHODS: Astemizole or terfenadine were incubated with human liver microsomes or recombinant cytochromes P450 in the absence or presence of chemical inhibitors and antibodies. RESULTS: Troleandomycin, a CYP3A4 inhibitor, markedly reduced the oxidation of terfenadine (26% of controls) in human liver microsomes, but showed only a marginal inhibition on the oxidation of astemizole (81% of controls). Three metabolites of astemizole were detected in a liver microsomal system, i.e. desmethylastemizole (DES-AST), 6-hydroxyastemizole (6OH-AST) and norastemizole (NOR-AST) at the ratio of 7.4 : 2.8 : 1. Experiments with recombinant P450s and antibodies indicate a negligible role for CYP3A4 on the main metabolic route of astemizole, i.e. formation of DES-AST, although CYP3A4 may mediate the relatively minor metabolic routes to 6OH-AST and NOR-AST. Recombinant CYP2D6 catalysed the formation of 6OH-AST and DES-AST. Studies with human liver microsomes, however, suggest a major role for a mono P450 in DES-AST formation. CONCLUSIONS: In contrast to terfenadine, a minor role for CYP3A4 and involvement of multiple P450 isozymes are suggested in the metabolism of astemizole. These differences in P450 isozymes involved in the metabolism of astemizole and terfenadine may associate with distinct pharmacokinetic influences observed with coadministration of drugs metabolized by CYP3A4.
Abstract: BACKGROUND: Cardiac arrhythmias have been linked to treatment with methadone and levacetylmethadol. HIV-positive patients often have conditions that place them at risk for QT interval prolongation including HIV-associated dilated cardiomyopathy, coronary artery disease as a consequence of highly active antiretroviral (ARV) therapy-associated metabolic syndrome, and uncorrected electrolyte abnormalities. As of February 14, 2006, no cases of adverse events related to QT interval prolongation have been reported in patients receiving buprenorphine, an opioid partial agonist and the newest drug approved for the treatment of opioid dependence. OBJECTIVE: To evaluate the effects of buprenorphine/naloxone alone and in combination with 1 of 5 ARV agents (efavirenz, nelfinavir, delavirdine, ritonavir, lopinavir/ritonavir) on the QT interval. METHODS: This study was prospective, open-label, and within-subject in design, with subjects serving as their own controls. In 50 HIV-negative, opioid-dependent subjects, electrocardiogram recordings were obtained at baseline, after receiving buprenorphine/naloxone for 2 weeks, and then following buprenorphine/naloxone plus ARV administration for 5-15 days at steady-state. QTc interval measurements were compared using mixed-model, repeated-measures ANOVA. Recent cocaine use and gender were considered covariates. RESULTS: Buprenorphine/naloxone alone and often in the presence of evidence for recent use of cocaine did not significantly alter the QT interval (p = 0.612). Buprenorphine/naloxone in combination with ARVs caused a statistically, but not clinically, significant increase (p = 0.005) in the QT interval. Subjects receiving buprenorphine/naloxone in combination with either delavirdine or ritonavir had the greatest increase in QTc intervals. CONCLUSIONS: Prolonged QT intervals were not observed in opioid-dependent subjects receiving buprenorphine/naloxone alone. QT interval increases were observed with buprenorphine/naloxone in combination with either delavirdine or ritonavir, which inhibit CYP3A4.
Abstract: Impairment of renal function is common among elderly patients due to an age-related decline in renal excretory function. In addition, many diseases such as hypertension and diabetes mellitus are associated with an accelerated decline in renal function. Renal dysfunction affects the metabolism of compounds and thus has important therapeutic consequences for drug safety. For pain patients who have reduced renal function such as those in palliative care, most opioids used for chronic pain treatment should be administered at reduced dosages, with increased dosage intervals, or not at all because of the risk of accumulation of the parent compound or its metabolites. For instance, for morphine or codeine, active metabolites are formed in the liver and cleared by the kidney and may therefore accumulate in cases of renal dysfunction. In contrast, buprenorphine can be administered at normal doses in patients with renal dysfunction because it is mainly excreted through the liver. In patients undergoing regular haemodialysis treatment, removal of an opioid during dialysis varies between individuals based upon a number of factors including the dialysis technique used. Morphine appears to be difficult to process in haemodialysis patients due to possible 'rebound' of metabolites between dialysis sessions. By contrast, the pharmacokinetics of buprenorphine are unchanged in haemodialysis patients, which means that there is no need for dose-reduction with this drug. Thus, in patients with reduced renal function, chronic renal insufficiency and haemodialysis, buprenorphine appears to be a safe choice when opioid treatment is initiated.
Abstract: AIMS: To determine the prevalence of corrected QT interval (QTc) prolongation among patients in opioid maintenance treatment (OMT) and to investigate mortality potentially attributable to QTc prolongation in the Norwegian OMT programme. PARTICIPANTS AND SETTING: Two hundred OMT patients in Oslo were recruited to the QTc assessment study between October 2006 and August 2007. The Norwegian register of all patients receiving OMT in Norway (January 1997-December 2003) and the national death certificate register were used to assess mortality. Mortality records were examined for the 90 deaths that had occurred among 2382 patients with 6450 total years in OMT. DESIGN AND MEASURES: The QTc interval was assessed by electrocardiography (ECG). All ECGs were examined by the same cardiologist, who was blind to patient history and medication. Mortality was calculated by cross-matching the OMT register and the national death certificate register: deaths that were possibly attributable to QTc prolongation were divided by the number of patient-years in OMT. FINDINGS: In the QTc assessment sample (n = 200), 173 patients (86.5%) received methadone and 27 (13.5%) received buprenorphine. In the methadone group, 4.6% (n = 8) had a QTc above 500 milliseconds; 15% (n = 26) had a QTc interval above 470 milliseconds; and 28.9% (n = 50) had a QTc above 450 milliseconds. All patients receiving buprenorphine (n = 27) had QTc results <450 milliseconds. A positive dose-dependent association was identified between QTc length and dose of methadone, and all patients with a QTc above 500 milliseconds were taking methadone doses of 120 mg or more. OMT patient mortality, where QTc prolongation could not be excluded as the cause of death, was 0.06/100 patient-years. Only one death among 3850 OMT initiations occurred within the first month of treatment. CONCLUSION: Of the methadone patients, 4.6% had QTc intervals above 500 milliseconds. The maximum mortality attributable to QTc prolongation was low: 0.06 per 100 patient-years.
Abstract: Opioid dependence is a significant and growing problem in the United States. For nearly a century, federal regulations have made it illegal for psychiatrists and other physicians to pharmacologically manage this condition in an office-based setting using opioids. The passage of the Drug Addiction Treatment Act of 2000 has made it possible for all physicians to prescribe buprenorphine to patients in such a setting. Buprenorphine, a partial mu-opoid receptor agonist, has unique pharmacologic properties that distinguish it from methadone and other medications used in the treatment of opioid dependence. It has been shown to be as effective as methadone and is generally safe and well-tolerated. It is available in two sublingual formulations: Subutex, which contains only buprenorphine, and Suboxone, which also contains naloxone. Physicians who wish to prescribe either must obtain a special waiver from the federal government and are currently limited to prescribing it for 30 patients at a time.
Abstract: OBJECTIVES: To study the effect of transdermal buprenorphine on QTc prolongation at dose levels of 10, 40, and 80 mcg/h, (BTDS 10, BTDS 40, BTDS 80). METHODS: Two randomized, placebo- and positive-controlled, parallel-group, dose-escalating clinical studies evaluated healthy adult subjects randomized to BTDS, placebo, or moxifloxacin in the first study; and to BTDS only, BTDS plus naltrexone, naltrexone alone at the same dose, placebo, or moxifloxacin in the second study. QT intervals were corrected for heart rate using data from each individual subject (QTcI). RESULTS: In the first study (n = 44), the maximum upper bounds of the 90% confidence interval (CI) for mean placebo-corrected change from baseline in QTcI across 13 time points over 24 h were: 10.0 msec for BTDS 10 (Day 6) and 13.3 msec for BTDS 40 (Day 13); and 17.0 msec (Day 6) and 15.5 msec (Day 13) for moxifloxacin, respectively. Similarly, in the second study (n = 66), the upper bound of the 90% CI for mean placebo-corrected change from baseline for QTcI was under 10 msec at all time points for BTDS 10 (maximum upper bound, 5.63 msec), over 10 msec at 5 time points for BTDS 40 (maximum 11.81 msec) and over 10 msec at all 13 time points for BTDS 80 (maximum, 14.14 msec). Naltrexone administered with BTDS eliminated the QTcI prolongation seen with supratherapeutic BTDS doses (BTDS 40, BTDS 80) administered without naltrexone. CONCLUSIONS: At the therapeutic dose of 10 mcg/h, BTDS has no clinically significant effect on QTc. At supratherapeutic doses of 40 and 80 mcg/h, BTDS treatment produces prolongation of QTcI similar in magnitude to that produced by a 400 mg dose of moxifloxacin. Despite the modest, dose-dependent increase in QTcI noted in these studies, transdermal buprenorphine has not been associated with proarrhythmic effects.
Abstract: AIMS: Opioid dependence is associated with high morbidity and mortality. Buprenorphine (BUP) is approved by the Food and Drug Administration to treat opioid dependence. There is a lack of clear consensus on the appropriate dosing of BUP due to interpatient physiological differences in absorption/disposition, subjective response assessment and other patient comorbidities. The objective of the present study was to build and validate robust physiologically based pharmacokinetic (PBPK) models for intravenous (IV) and sublingual (SL) BUP as a first step to optimizing BUP pharmacotherapy. METHODS: BUP-PBPK modelling and simulations were performed using SimCyp® by incorporating the physiochemical properties of BUP, establishing intersystem extrapolation factors-based in vitro-in-vivo extrapolation (IVIVE) methods to extrapolate in vitro enzyme activity data, and using tissue-specific plasma partition coefficient estimations. Published data on IV and SL-BUP in opioid-dependent and non-opioid-dependent patients were used to build the models. Fourteen model-naïve BUP-PK datasets were used for inter- and intrastudy validations. RESULTS: The IV and SL-BUP-PBPK models developed were robust in predicting the multicompartment disposition of BUP over a dosing range of 0.3-32 mg. Predicted plasma concentration-time profiles in virtual patients were consistent with reported data across five single-dose IV, five single-dose SL and four multiple dose SL studies. All PK parameter predictions were within 75-137% of the corresponding observed data. The model developed predicted the brain exposure of BUP to be about four times higher than that of BUP in plasma. CONCLUSION: The validated PBPK models will be used in future studies to predict BUP plasma and brain concentrations based on the varying demographic, physiological and pathological characteristics of patients.
Abstract: Pain management in end stage renal disease (ESRD) patients is a complex and challenging task to accomplish, and effective pain and symptom control improves quality of life. Pain is prevalent in more than 50% of hemodialysis patients and up to 75% of these patients are treated ineffectively due to its poor recognition by providers. A good history for PQRST factors and intensity assessment using visual analog scale are the initial steps in the management of pain followed by involvement of palliative care, patient and family counseling, discussion of treatment options, and correction of reversible causes. First line should be conservative management such as exercise, massage, heat/cold therapy, acupuncture, meditation, distraction, music therapy, and cognitive behavioral therapy. Analgesics are introduced according to WHO guidelines (by the mouth, by the clock, by the ladder, for the individual, and attention to detail) using three-step analgesic ladder model. Neuropathic pain can be controlled by gabapentin and pregabalin. Substitution/addition of opioid analgesics are indicated if pain control is not optimal. Commonly used opioids in ESRD patients are tramadol, oxycodone, hydromorphone, fentanyl, methadone, and buprenorphine. Methadone, fentanyl, and buprenorphine are the ideal analgesics in ESRD. However, complex pain syndrome requires multidrug analgesic regimen comprising opioids, non-opioids, and adjuvant medication, which should be individualized to the patient to achieve adequate pain control.