The influence of hyperlipidemia on the pharmacodynamic and pharmacokinetic aspects of lipophilic drugs was explored. The antiarrhythmic, amiodarone, and the antifungal, ()-ketoconazole, were used as model drugs. Experimental hyperlipidemia was induced in rat using poloxamer 407 and two sensitive novel HPLC assays were developed. In a multiple dosing study, hyperlipidemia increased amiodarone plasma concentrations, heart concentrations and electrocardiographic changes. The amiodarone heart uptake could not be totally attributed to its unbound fraction, where the cardiac very low density lipoprotein receptors seemed to play a role in the uptake of bound drug. Amiodarone liver metabolism in presence and absence of hyperlipidemia was studied using isolated primary rat liver hepatocytes. The metabolism of amiodarone was lower in hepatocytes isolated from hyperlipidemic than those from normolipidemic rats. Hyperlipidemic serum resulted in a decrease in amiodarone metabolism and when coincubated, the expected decrease in unbound fraction seemed to resulted in greater inhibition of metabolism. ()-Ketoconazole showed stereoselectivity in its pharmacokinetics in rat with (+)-ketoconazole showing higher plasma concentrations than its antipode. This was attributed to its higher protein binding. There was no difference in the total bioavailability of the two enantiomers. Ketoconazole enantiomers exhibited nonlinear pharmacokinetics. In normolipidemic rat plasma ketoconazole enantiomers were more than 95% bound to lipoprotein deficient fraction. Hyperlipidemia resulted in shifting both enantiomers 20% to very low density and low density lipoprotein fractions. In a pharmacokinetic assessment, hyperlipidemia was found to increase ketoconazole enantiomer volume of distribution. Moreover, the stereoselectivity ratios of most pharmacokinetic parameters were changed. After oral dosing, the uptake of (-)-ketoconazole was significantly decreased. Since ketoconazole is used as a potent CYP3A inhibitor, alteration in liver concentrations of (-)-ketoconazole, the more potent inhibitory enantiomer, could decrease its CYP inhibitory potential. Hyperlipidemia potentiated the CYP-mediated interaction between ketoconazole and midazolam with significantly higher midazolam AUC and lower clearance. This was attributed to the inhibitory action of ketoconazole and the effect of hyperlipidemia on the binding of midazolam. Hyperlipidemia was found to unexpectedly decrease midazolam unbound fraction in plasma. In conclusion, the findings could explain some unexpected dose versus effect outcomes in hyperlipidemic patients receiving amiodarone or ketoconazole. / Pharmaceutical Sciences

No description available.

Amiodarone is a potent antidysrhythmic agent that can cause potentially life-threatening pulmonary fibrosis. Accumulating evidence has demonstrated that myofibroblast differentiation is related to the pathogenesis of pulmonary fibrosis. In the present study, we treated human embryonic lung fibroblasts (HELFs) with amiodarone, and investigated the relative molecular mechanism of amiodarone-induced pulmonary fibrosis and pathway determinants PD98059 (extracellular signal-regulated kinase (ERK) inhibitor) and SB203580 (p38 mitogen-activated protein kinase (MAPK) inhibitor). Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8). The secretion of collagen Ⅰ was detected by ELISA. The expressions of α-smooth muscle actin (α-SMA), vimentin, phosphorylated ERK1/2 (p-ERK1/2), ERK1/2, phosphorylated p38 MAPK (p-p38), and p38 MAPK were investigated using Western blot analysis. The levels of α-SMA and vimentin were also determined by immunofluorescence and qRT-PCR. We report that amiodarone promoted cell proliferation and collagen Ⅰ secretion, induced α-SMA and vimentin protein and mRNA expression accompanied by increased phosphorylation of ERK1/2 and p38 MAPK, and furthermore, PD98059 and SB203580 remarkably reduced the proliferative response of HELFs compared with amiodarone group and greatly attenuated α-SMA, vimentin and collagen Ⅰ protein production induced by amiodarone. Taken together, our study suggests that amiodarone regulates cell proliferation and myofibroblast differentiation in HELFs through modulating ERK1/2 and p38 MAPK pathways, and these signal pathways may therefore represent an attractive treatment modality in amiodarone-induced pulmonary fibrosis.

Background: Amiodarone (AM) is a widely used anti-arrhythmic medication. Its utility is, however, limited by adverse side effects. The mechanism of amiodarone-induced toxicity (APT) in the lungs is attributed primarily to stimulation of the angiotensin enzyme system leading to lung cell apoptosis and cell death. This mechanism has been demonstrated by in vitro and in vivo experimental animal studies. To date, however, no in vivo human studies have confirmed this mechanism for APT. Purpose: This study was undertaken to determine whether angiotensin converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARB) offer a protective effect against APT in humans. Demonstration of a protective effect of an ACE-I or ARB would suggest that stimulation of the angiotensin enzyme system may be a key process in APT. Design: An 8-year retrospective analysis of all patients on AM therapy at the James H. Quillen Veterans Affairs Medical Center was undertaken. Results: A total of 1000 patients on AM were identified. One-hundred-and-seventeen were excluded from the study. Five-hundred-and-twenty-four patients were simultaneously on an ACE-I or ARB. The remaining 359 patients were not. Pulmonary toxicity attributed to AM was identified in five and 14 patients with and without concomitant ACE-I or ARB therapy, respectively. The APT rate for the entire patient sample was 2.2%. APT occurred in 1% of patients on an ACE-I or ARB and in 3.9% of patients not taking an ACE-I or ARB. This observed difference in percentage of APT was statistically significant. Conclusion: The concomitant use of ACE-I or ARB in patients taking AM appears to offer a protective effect against APT. This observation suggests that the stimulation of the angiotensin enzyme system may play an important role in APT in humans.

What is known and objective: Amiodarone, a commonly used class III antiarrhythmic agent notable for a relatively long half-life of up to 6 months and its pronounced adverse effect profile, is used for both acute and chronic management of cardiac arrhythmias. Chronic use of amiodarone has been associated with asymptomatic hepatotoxicity; however, acute toxicity is thought to be uncommon. There are only six reported cases of acute liver failure (ALF) secondary to amiodarone. In all these cases the outcome of death during the same hospitalization resulted. We aimed to report the only case of acute liver failure secondary to amiodarone infusion in the existing literature where the patient survived. Case summary: A 79-year-old woman admitted with atrial flutter was being treated with intravenous (IV) amiodarone when she abruptly developed coagulopathy, altered mental status and liver enzyme derangement. She was diagnosed with acute liver failure (ALF) secondary to an amiodarone adverse drug reaction, with a calculated score of seven on the Naranjo adverse drug reaction probability scale. Amiodarone was immediately withheld, and N-acetylcysteine (NAC) was initiated. Clinical improvement was seen within 48 hours of holding the drug and within 24 hours of initiating NAC. On post-hospital follow-up visit she was reported to have complete recovery. What is new and conclusion: This report emphasizes the importance of monitoring liver enzymes and mental status while a patient is being administered IV amiodarone. N-acetylcysteine administration may have possibly contributed to the early and successful recovery from ALF in our patient. To date, she is the only patient in the existing literature who has been reported to survive ALF secondary to amiodarone administration.

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13481号 / 論医博第2256号 / 新制||医||1059(附属図書館) / (主査)教授 平井 豊博, 教授 岩田 想, 教授 秋山 芳展 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

<p><strong>BACKGROUND</strong></p> <p>Amiodarone is believed to inhibit the hepatic metabolism of warfarin, potentiating its hypoprothrombinemic effect and increasing the risk of hemorrhage. The consequences of this drug interaction on important clinical outcomes are unknown.</p> <p><strong>METHODOLOGY</strong></p> <p>Using linked health administrative databases, we conducted a population-based retrospective cohort study among Ontario residents aged 66 years or older who had been treated with warfarin therapy for at least 6 months. Within this group, we identified subjects who initiated amiodarone while on warfarin. Each of these subjects was matched to a subject not treated with amiodarone on age, sex, year of cohort entry, and a high dimensional propensity score. The primary outcome was a hospitalization due to a hemorrhagic event within 30 days of follow-up. In a secondary analysis, we examined in-hospital mortality following hospitalization for major hemorrhage.</p> <p><strong>RESULTS</strong></p> <p>We identified 60,497 eligible patients between July 1, 1994 and March 31, 2009. Of these, 11,665 (19.3%) received a new prescription for amiodarone while receiving ongoing warfarin therapy and 7,124 (61.1%) of these were matched to a subject who was not exposed to amiodarone while receiving warfarin therapy. The median age at cohort entry of the matched cohort was 76 years, 51.6% in the cohort were male, 14.5% lived in a rural location, 2.8% had a bleed in the past year, and 21.6% had a diagnosis of congestive heart failure in the past year. Fifty-six amiodarone recipients experienced a hemorrhagic event (0.8%) as compared to 23 individuals (0.3%) in the non-exposed group at 30 day follow-up (adjusted hazard ratio (HR) = 2.45; 95% CI, 1.49 to 4.02). Seven patients in the amiodarone group died after hospitalization for a hemorrhage versus four in the non-exposed group (adjusted HR = 1.74; 95% CI, 0.25 to 12.24).</p> <p><strong>CONCLUSION</strong></p> <p>Initiation of amiodarone in patients on chronic warfarin therapy was associated with a two-fold increase in the risk of hospitalization due to a hemorrhagic event. Physicians should closely monitor the response to warfarin following initiation of amiodarone.</p> / Master of Science (MSc)

Com o objetivo de se avaliar a importância do \"clearance\" do dietilenotriamino-pentacetato marcado com Tecnécio 99m (DTPA-Tecnécio-99m) em portadores de pneumopatia por amiodarona foram estudados 40 indivíduos, em quatro grupos. Grupo I: 10 voluntários normais, assintomáticos e não fumantes (8 homens e 2 mulheres), com média de idade de 56,80 anos. Grupo II: 10 voluntários normais, assintomáticos e fumantes (6 homens e 4 mulheres ), com média de idade de 27,50 anos. Grupo III: 10 pacientes não fumantes ( 4 homens e 5 mulheres ), com média de idade de 52,90 anos. Todos faziam uso crônico de amiodarona por via oral. Grupo IV: 10 pacientes portadores de pneumopatia por amiodarona, quatro ex-fumantes, dois fumantes e quatro não fumantes ( 8 homens e 2 mulheres) com média de idade de 52,90 anos. Todos faziam uso de amiodarona por via oral e nenhum fumou nas 4 semanas que precederam o estudo. Após espirometria que constou do registro da curva volume-tempo, todos inalaram 4 ml de solução salina contendo 740 MBq de DTPA Tecnécio-99m, durante cinco minutos. Através de uma c~mara de cintilação computadorizada foram obtidas imagens pulmonares, definindo-se 9 áreas de interesse. Para cada região escolhida foi determinada uma curva de \"clearance\" extraindo-se o valor de meia-vida biológica em minu- tos ( T 1/2 ) e a taxa percentual de \" clearance\" alvéolo capilar do radioaerossol por minuto (K%/min). Observamos que, das variáveis espirométricas consideradas, a capacidade vital forçada (CVF) e o volume expiratório forçado no 1 segundo (VEF1) mostraram diferenças significantes entre os grupos I e IV. A contagem total de radioatividade de ambos os pulmões não mostrou relação com a CVF e o VEF1. O \" clearance \" pulmonar do DTPA Tecnécio-99m foi maior nos grupos 11 e IV, porém não permitindo sua diferenciação. Estes resultados permitem concluir: Os pacientes portadores de pneumonite por amiodaro- na apresentam\" clearance \" alvéolo-capilar de DTPA Tecnécio-99m significativamente maior que os indivíduos do grupo de normais não fumantes. Este fato também se verificou em relação aos pacientes em uso crônico de amiodarona mas sem evidências de pneumopatia. Não é possível diferenciar os fumantes dos portadores de pneumonite por amiodarona através da análise da integridade da barreira alvéolo-epitelial com DTPA Tecnécio-99m. Comparativamente, o estudo da integridade alvéolo-epitelial pelo \"clearance\" pulmonar de DTPA Tecnécio-99m é mais sensível que a espirometria na avaliação da pneumonite por amiodarona, permitindo diferenciar estes pacientes dos que fazem uso crônico da droga / In order to evaluate the role of the clearance of 99m Technetium chelated to diethylenetriamine-penta-acetate ( 99mTc-DTPA) in amiodarone induced pulmonary disease, 40 individuaIs were studied in four groups. Group I: 10 normal non smoking volunteers (8 men and 2 women ), whose mean age was 56.80 years. Group lI: 10 normal smoking volunteers ( 6 men and 4 women ), aging 27.50 years in average. Group III: 10 non smoking patients ( 4 men and women ), aging 52.90 years in average, who were chronically taking oral amiodarone. Group IV: 10 patients with amiodarone induced pul- monary disease (8 men and 2 women), four non-smokers, two smokers and four previous smokers. Their mean age was 62.90 years. AIl of them were taking oral amiodarone and none has smoked in the 4 weeks previous to the study. After spirometry, where a volume-time curve was registered, alI individuaIs inhaled 740 MBq of 99mTc-DTPA diluted in 4 ml of saline, for five minutes. Pulmonary images were obtained in a computadorized scintillation camera and 9 regions of interest were selected. A clearance curve of each region was determined, from which the effective half-life in minutes (T 1/2 ) and the alveolar-capilar clearance rate per minute ( k%/min ) of the radiolabeled aerosol were mea- sured. The spirometric analys disclosed a statistically lower value of the forced vital capacity ( FVC ) and forced expiratory volume in the first second ( FEV1 ) in the patients of group IV when compared to group I. The total radioactivity count for both lungs were not influenced by FVC and FEV1. The 99mTc-DTPA clearance rate was higher in groups 11 and IV, but these two groups could not be statistically differentiated. Based on these results it 1s concluded: patients with amiodarone induced pulmonary pneumonitis have higher clearance rates of 99m Tc-DTPA than normal non smoking controls and than patients taking amiodarone but with no lung toxicity. It is not possible to separate patients with amiodarone induced disease from normal smokers by determining 99m Tc-DTPA clearance rates. The determination of the alveolar-epithelial barrier integrity by 99m Tc-DTPA clearance rate is a more sensitive test than spirometry in the evaluation of amiodarone induced pneumonitis making it possible to differentiate these patients from those who take the drug and have no lung toxicity

Com o objetivo de se avaliar a importância do \"clearance\" do dietilenotriamino-pentacetato marcado com Tecnécio 99m (DTPA-Tecnécio-99m) em portadores de pneumopatia por amiodarona foram estudados 40 indivíduos, em quatro grupos. Grupo I: 10 voluntários normais, assintomáticos e não fumantes (8 homens e 2 mulheres), com média de idade de 56,80 anos. Grupo II: 10 voluntários normais, assintomáticos e fumantes (6 homens e 4 mulheres ), com média de idade de 27,50 anos. Grupo III: 10 pacientes não fumantes ( 4 homens e 5 mulheres ), com média de idade de 52,90 anos. Todos faziam uso crônico de amiodarona por via oral. Grupo IV: 10 pacientes portadores de pneumopatia por amiodarona, quatro ex-fumantes, dois fumantes e quatro não fumantes ( 8 homens e 2 mulheres) com média de idade de 52,90 anos. Todos faziam uso de amiodarona por via oral e nenhum fumou nas 4 semanas que precederam o estudo. Após espirometria que constou do registro da curva volume-tempo, todos inalaram 4 ml de solução salina contendo 740 MBq de DTPA Tecnécio-99m, durante cinco minutos. Através de uma c~mara de cintilação computadorizada foram obtidas imagens pulmonares, definindo-se 9 áreas de interesse. Para cada região escolhida foi determinada uma curva de \"clearance\" extraindo-se o valor de meia-vida biológica em minu- tos ( T 1/2 ) e a taxa percentual de \" clearance\" alvéolo capilar do radioaerossol por minuto (K%/min). Observamos que, das variáveis espirométricas consideradas, a capacidade vital forçada (CVF) e o volume expiratório forçado no 1 segundo (VEF1) mostraram diferenças significantes entre os grupos I e IV. A contagem total de radioatividade de ambos os pulmões não mostrou relação com a CVF e o VEF1. O \" clearance \" pulmonar do DTPA Tecnécio-99m foi maior nos grupos 11 e IV, porém não permitindo sua diferenciação. Estes resultados permitem concluir: Os pacientes portadores de pneumonite por amiodaro- na apresentam\" clearance \" alvéolo-capilar de DTPA Tecnécio-99m significativamente maior que os indivíduos do grupo de normais não fumantes. Este fato também se verificou em relação aos pacientes em uso crônico de amiodarona mas sem evidências de pneumopatia. Não é possível diferenciar os fumantes dos portadores de pneumonite por amiodarona através da análise da integridade da barreira alvéolo-epitelial com DTPA Tecnécio-99m. Comparativamente, o estudo da integridade alvéolo-epitelial pelo \"clearance\" pulmonar de DTPA Tecnécio-99m é mais sensível que a espirometria na avaliação da pneumonite por amiodarona, permitindo diferenciar estes pacientes dos que fazem uso crônico da droga / In order to evaluate the role of the clearance of 99m Technetium chelated to diethylenetriamine-penta-acetate ( 99mTc-DTPA) in amiodarone induced pulmonary disease, 40 individuaIs were studied in four groups. Group I: 10 normal non smoking volunteers (8 men and 2 women ), whose mean age was 56.80 years. Group lI: 10 normal smoking volunteers ( 6 men and 4 women ), aging 27.50 years in average. Group III: 10 non smoking patients ( 4 men and women ), aging 52.90 years in average, who were chronically taking oral amiodarone. Group IV: 10 patients with amiodarone induced pul- monary disease (8 men and 2 women), four non-smokers, two smokers and four previous smokers. Their mean age was 62.90 years. AIl of them were taking oral amiodarone and none has smoked in the 4 weeks previous to the study. After spirometry, where a volume-time curve was registered, alI individuaIs inhaled 740 MBq of 99mTc-DTPA diluted in 4 ml of saline, for five minutes. Pulmonary images were obtained in a computadorized scintillation camera and 9 regions of interest were selected. A clearance curve of each region was determined, from which the effective half-life in minutes (T 1/2 ) and the alveolar-capilar clearance rate per minute ( k%/min ) of the radiolabeled aerosol were mea- sured. The spirometric analys disclosed a statistically lower value of the forced vital capacity ( FVC ) and forced expiratory volume in the first second ( FEV1 ) in the patients of group IV when compared to group I. The total radioactivity count for both lungs were not influenced by FVC and FEV1. The 99mTc-DTPA clearance rate was higher in groups 11 and IV, but these two groups could not be statistically differentiated. Based on these results it 1s concluded: patients with amiodarone induced pulmonary pneumonitis have higher clearance rates of 99m Tc-DTPA than normal non smoking controls and than patients taking amiodarone but with no lung toxicity. It is not possible to separate patients with amiodarone induced disease from normal smokers by determining 99m Tc-DTPA clearance rates. The determination of the alveolar-epithelial barrier integrity by 99m Tc-DTPA clearance rate is a more sensitive test than spirometry in the evaluation of amiodarone induced pneumonitis making it possible to differentiate these patients from those who take the drug and have no lung toxicity

Adverse effects of amiodarone are rarely seen in pediatric patients, but may occur if amiodarone is applied for long-term treatment. Two rather rare phenomena are blue-gray skin pigmentation and pulmonary mass. They represent important differential diagnoses from more common clinical complications like pneumonia and drug-induced toxic skin lesions.