Withdrawal syndrome following cessation of antihypertensive drug therapy

In this study, a review of the available information concerning abrupt withdrawal of antihypertensive drug therapy is presented. Abrupt withdrawal of these drugs can produce a syndrome of sympathetic overactivity that includes nervousness, tachycardia, headache, agitation and nausea 36-72 h after cessation of the drug. A withdrawal syndrome may occur after discontinuation of almost all types of antihypertensive drugs, but mostly occurs with clonidine, beta-blockers, methyldopa and guanabenz. Less commonly can produce a rapid increase of the blood pressure to pre-treatment levels or above, or both and/or myocardial ischaemia. Although the exact incidence of the syndrome is not known, it appears to be rare, at least in patients receiving standard doses of the above antihypertensive drugs. The best treatment is prevention. In this study regarding the withdrawal syndrome that follows cessation of antihypertensive drugs therapy, a reference to the abrupt discontinuation of the main categories of antihypertensive drugs is also attempted.     

Warm storage of whole blood for 72 hours

BACKGROUND: In field emergency medicine, fresh whole-blood units are stored at room temperature up to 24 hours or occasionally longer. Few data exist on the integrity and in vitro functional properties of whole blood stored warm beyond 24 hours. STUDY DESIGN AND METHODS: Ten citrate phosphate dextrose solution whole-blood units were collected and divided into two equal volumes. One-half of each unit was stored at 19 degrees C and the other half was stored at 25 degrees C, encompassing the accepted range for room temperature storage. At 6, 24, 48, and 72 hours, aliquots were collected from each unit and whole blood analyzed for cell counts, gases, and clotting function with thromboelastography, red cells for intracellular analytes, platelet (PLT)-rich plasma for aggregometry, and the supernatant for hemoglobin, potassium, glucose, lactate, and plasma clotting studies. RESULTS: Whole-blood units stored at room temperature maintained cellular counts and coagulation activity for up to 72 hours. Units stored at 19 degrees C demonstrated greater RBC adenosine triphosphate and 2,3-diphosphoglycerate (DPG) content and stronger responses in PLT aggregation studies when compared with 25 degrees C storage. No significant hemolysis was observed, and no bacterial growth was detected. CONCLUSION: Storage of whole blood at room temperature for 72 hours leads to marked reductions in pH and DPG, but the observed reduction in PLT function and plasma coagulation factor activity was surprisingly modest compared to literature values. These findings should prompt additional investigation, given their potential importance for whole blood processing and field-expedient transfusion.     

Procalcitonin decrease over 72 hours in US critical care units predicts fatal outcome in sepsis patients

Introduction

Close monitoring and repeated risk assessment of sepsis patients in the intensive care unit (ICU) is important for decisions regarding care intensification or early discharge to the ward. We studied whether considering plasma kinetics of procalcitonin, a biomarker of systemic bacterial infection, over the first 72 critical care hours improved mortality prognostication of septic patients from two US settings.

Methods

This retrospective analysis included consecutively treated eligible adults with a diagnosis of sepsis from critical care units in two independent institutions in Clearwater, FL and Chicago, IL. Cohorts were used for derivation or validation to study the association between procalcitonin change over the first 72 critical care hours and mortality.

Results

ICU/in-hospital mortality rates were 29.2%/31.8% in the derivation cohort (n = 154) and 17.6%/29.4% in the validation cohort (n = 102). In logistic regression analysis of both cohorts, procalcitonin change was strongly associated with ICU and in-hospital mortality independent of clinical risk scores (Acute Physiology, Age and Chronic Health Evaluation IV or Simplified Acute Physiology Score II), with area under the curve (AUC) from 0.67 to 0.71. When procalcitonin decreased by at least 80%, the negative predictive value for ICU/in-hospital mortality was 90%/90% in the derivation cohort, and 91%/79% in the validation cohort. When procalcitonin showed no decrease or increased, the respective positive predictive values were 48%/48% and 36%/52%.

Discussion

In septic patients, procalcitonin kinetics over the first 72 critical care hours provide prognostic information beyond that available from clinical risk scores. If these observations are confirmed, procalcitonin monitoring may assist physician decision-making regarding care intensification or early transfer from the ICU to the floor.     

Pharmacokinetics and pharmacodynamics of once-daily versus twice-daily raltegravir in treatment-naive HIV-infected patients

QDMRK was a phase III clinical trial of raltegravir given once daily (QD) (800-mg dose) versus twice daily (BID) (400 mg per dose), each in combination with once-daily coformulated tenofovir-emtricitabine, in treatment-naive HIV-infected patients. Pharmacokinetic (PK) and pharmacokinetic/pharmacodynamic (PK/PD) analyses were conducted using a 2-step approach: individual non-model-based PK parameters from observed sparse concentration data were determined, followed by statistical analysis of potential relationships between PK and efficacy response parameters after 48 weeks of treatment. Sparse PK sampling was performed for all patients (QD, n = 380; BID, n = 384); selected sites performed an intensive PK evaluation at week 4 (QD, n = 22; BID, n = 20). In the intensive PK subgroup, daily exposures (area under the concentration-time curve from 0 to 24 h [AUC(0-24)]) were similar between the two regimens, but patients on 800 mg QD experienced ~4-fold-higher maximum drug concentration in plasma (C(max)) values and ~6-fold-lower trough drug concentration (C(trough)) values than those on 400 mg BID. Geometric mean (GM) C(trough) values were similarly lower in the sparse PK analysis. With BID dosing, there was no indication of any significant PK/PD association over the range of tested PK parameters. With QD dosing, C(trough) values correlated with the likelihood of virologic response. Failure to achieve an HIV RNA level of <50 copies/ml appeared predominantly at high baseline HIV RNA levels in both treatment arms and was associated with lower values of GM C(trough) in the 800-mg-QD arm, though other possible drivers of efficacy, such as time above a threshold concentration, could not be evaluated due to the sparse sampling scheme. Together, these findings emphasize the importance of the shape of the plasma concentration-versus-time curve for long-term efficacy.     

Pharmacokinetics of drug overdose

Drugs ingested in overdose can have altered pharmacokinetics of absorption, distribution, and elimination. The pathophysiologic consequences of overdose can also change a drug's pharmacokinetic properties. Many toxicologic interventions are based on modifying the drug's pharmacokinetics (e.g., impairing absorption or enhancing elimination). Serum drug monitoring, even with its limitations, does have a role in managing the patient who has taken an overdose.     

Pharmacokinetics of antiretroviral regimens containing tenofovir disoproxil fumarate and atazanavir-ritonavir in adolescents and young adults with human immunodeficiency virus infection

The primary objective of this study was to measure atazanavir-ritonavir and tenofovir pharmacokinetics when the drugs were used in combination in young adults with human immunodeficiency virus (HIV). HIV-infected subjects > or =18 to <25 years old receiving (> or =28 days) 300/100 mg atazanavir-ritonavir plus 300 mg tenofovir disoproxil fumarate (TDF) plus one or more other nucleoside analogs underwent intensive 24-h pharmacokinetic studies following a light meal. Peripheral blood mononuclear cells were obtained at 1, 4, and 24 h postdose for quantification of intracellular tenofovir diphosphate (TFV-DP) concentrations. Twenty-two subjects were eligible for analyses. The geometric mean (95% confidence interval [CI]) atazanavir area under the concentration-time curve from 0 to 24 h (AUC(0-24)), maximum concentration of drug in serum (C(max)), concentration at 24 h postdose (C(24)), and total apparent oral clearance (CL/F) values were 35,971 ng x hr/ml (30,853 to 41,898), 3,504 ng/ml (2,978 to 4,105), 578 ng/ml (474 to 704), and 8.3 liter/hr (7.2 to 9.7), respectively. The geometric mean (95% CI) tenofovir AUC(0-24), C(max), C(24), and CL/F values were 2,762 ng.hr/ml (2,392 to 3,041), 254 ng/ml (221 to 292), 60 ng/ml (52 to 68), and 49.2 liter/hr (43.8 to 55.3), respectively. Body weight was significantly predictive of CL/F for all three drugs. For every 10-kg increase in weight, there was a 10%, 14.8%, and 6.8% increase in the atazanavir, ritonavir, and tenofovir CL/F, respectively (P < or = 0.01). Renal function was predictive of tenofovir CL/F. For every 10 ml/min increase in creatinine clearance, there was a 4.6% increase in tenofovir CL/F (P < 0.0001). The geometric mean (95% CI) TFV-DP concentrations at 1, 4, and 24 h postdose were 96.4 (71.5 to 130), 93.3 (68 to 130), and 92.7 (70 to 123) fmol/million cells. There was an association between renal function, tenofovir AUC, and tenofovir C(max) and intracellular TFV-DP concentrations, although none of these associations reached statistical significance. In these HIV-infected young adults treated with atazanavir-ritonavir plus TDF, the atazanavir AUC was similar to those of older adults treated with the combination. Based on data for healthy volunteers, a higher tenofovir AUC may have been expected, but was not seen in these subjects. This might be due to faster tenofovir CL/F because of higher creatinine clearance in this age group. Additional studies of the exposure-response relationships of this regimen in children, adolescents, and adults would advance our knowledge of its pharmacodynamic properties.     

胺碘酮的药代学与作用（一）

胺碘酮（amiodarone）原称乙胺碘呋酮，已在临床应用40年，其强大的抗心律失常作用已被越来越多的循证医学的结果所证实。目前，胺碘酮是临床应用最多、最广泛的抗心律失常药物，在美国和欧洲，其占抗心律失常药物处方的1／3，而在拉美国家高达70％。     

Pharmacokinetics and pharmacodynamics of once-daily arbekacin during continuous venovenous hemodiafiltration in critically ill patients

This study examined the pharmacokinetics of arbekacin during continuous venovenous hemodiafiltration (CVVHDF) and assessed the pharmacodynamics to consider arbekacin dosage adaptation in CVVHDF. Arbekacin was administered by 0.5-h infusion once daily, using a polymethyl methacrylate membrane hemofilter, to three critically ill patients undergoing CVVHDF; the flow rates were 0.8 l/h for the filtrate and 0.6 l/h for the dialysate. The drug concentrations in plasma and in the filtrate-dialysate were determined using a fluorescence polarization immunoassay and analyzed pharmacokinetically. The average sieving coefficient of arbekacin was 0.739 and the average drug clearance by CVVHDF was 1.03 l/h. A pharmacokinetic model with three compartments (1, central; 2, peripheral; 3, filtrate-dialysate side hemofilter) accurately reflected the concentration-time data for both plasma and filtrate-dialysate. The pharmacokinetic model assessed the pharmacodynamic profile of arbekacin once-daily regimens (0.5-h infusions) at filtrate-dialysate flow rates of 1.4 and 2.8 l/h, and demonstrated that only the 150-mg and 200-mg regimens achieved an effective target range for C_max (9–20 μg/ml), suggesting that empirical dosages lower than the usual 150–200 mg should be avoided in patients undergoing CVVHDF. The minimum regimens needed to achieve an effective pharmacodynamic target for the free C_max/MIC ratio (>8) were 75 mg for an MIC of 0.5 μg/ml, 200 mg for an MIC of 2 μg/ml, and 400 mg for an MIC of 4 μg/ml. These results will help us to better understand the pharmacokinetics of arbekacin during CVVHDF, while also helping in the selection of the appropriate arbekacin regimens, based on a pharmacodynamic assessment, for patients receiving this renal replacement therapy.     

Pharmacokinetics of and short-term virologic response to low-dose 400-milligram once-daily raltegravir maintenance therapy

Because studies showed similar viral suppression with lower raltegravir doses and because Asians usually have high antiretroviral concentrations, we explored low-dose raltegravir therapy in Thais. Nineteen adults on raltegravir at 400 mg twice daily (BID) with HIV RNA loads of <50 copies/ml were randomized to receive 400 mg once daily (QD) or 800 mg QD for 2 weeks, followed by the other dosing for 2 weeks. Intensive pharmacokinetic analyses were performed, and HIV RNA was monitored. Two patients were excluded from the 400-mg QD analysis due to inevaluable pharmacokinetic data. The mean patient weight was 58 kg. Mean pharmacokinetic values were as follows: for raltegravir given at 400 mg BID, the area under the concentration-time curve from 0 to 12 h (AUC_0-12) was 15.6 mg/liter-h and the minimum plasma drug concentration (C_trough) was 0.22 mg/liter; for raltegravir given at 800 mg QD, the AUC_0-24 was 33.6 mg/liter-h and the C_trough was 0.06 mg/liter; and for raltegravir given at 400 mg QD, the AUC_0-24 was 18.6 mg/liter-h and the C_trough was 0.08 mg/liter. The HIV RNA load was <50 copies/ml at each dose level. Compared to the adjusted AUC_0-24 for Westerners on raltegravir at 400 mg BID, Thais on the same dose had double the AUC_0-24 and those on raltegravir at 400 mg QD had a similar AUC_0-24. More patients had a C_trough of <0.021 mg/liter on raltegravir at 400 mg QD (9/17 patients) than on raltegravir at 800 mg QD (1/19 patients) or 400 mg BID (0/19 patients). Seventeen patients used raltegravir at 400 mg QD for a median of 35 weeks; two had confirmed HIV RNA loads between 50 and 200 copies/ml, and both had low C_trough values. Low-dose raltegravir could be a cost-saving option for maintenance therapy in Asians or persons with low body weight. However, raltegravir at 400 mg QD was associated with a low C_trough and with a risk for HIV viremia. Raltegravir at 200 or 300 mg BID should be studied, but new raltegravir formulations will be needed.     

Pharmacokinetics of tobramycin in adults with cystic fibrosis: implications for once-daily administration

Once-daily administration of aminoglycosides is routinely used in many institutions. However, comparative efficacy data for patients with cystic fibrosis (CF) are lacking. The purpose of the present study was to compare the predicted pharmacodynamic activity of tobramycin at 10 mg/kg of body weight/day administered every 24 h (q24h), q12h, and q8h. Pharmacokinetic (PK) data were derived from analysis of data on the drug concentration in sera from 60 adult CF patients. Individual maximum a posteriori probability Bayesian PK parameter values were used to construct serum concentration-versus-time curves and to determine various indices (peak concentration/MIC ratio [peak/MIC], area under the concentration-time curve/MIC ratio [AUC/MIC], and time that the concentration was less than the MIC [T相似文献   

Effects of 72 hours sleep deprivation on wound healing in the rat

The purpose of this study was to examine effects of sleep deprivation on cellular and biochemical markers of wound healing. Expanded polytetrafluoroethylene tubing inserted in subcutaneous tissue created miniature wounds in the dorsal skin of 12 rats. Seven days later, 6 rats were deprived of sleep by the platform method for 72 hr; control rats remained on usual sleep/wake routines. Numbers of macrophages, granulocytes, fibroblasts, and extent of connective tissue present and total amounts of protein, DNA, and hydroxyproline in the implants were not different between sleep-deprived and control rats. There is no evidence from this study that sleep deprivation impairs cellular and biochemical indicators of tissue repair. © 1997 John Wiley & Sons, Inc. Res Nurs Health 20: 259–267, 1997     

胸外科术后72小时内患者舒适状况及影响因素研究

目的了解胸外科术后72h内患者的舒适状况及影响因素。方法采用便利抽样方法,用Kolcaba简化的舒适状况量表(GCQ)对123例胸外科术后24h、48h、72h患者分别进行测量。结果胸外科术后72h内患者的舒适为中高度舒适,且与术后时间密切相关,随着术后时间的延长舒适度逐渐提高(P<0.01);术后72h内患者对陪伴的需求高,并且术后疼痛和疲倦较剧烈;不同性别、婚姻状况、医疗付费方式和家庭经济状况对术后72h内患者的舒适有显著相关(P<0.05)。结论临床医护人员应对术后患者适当放宽陪伴制度,并关注术后患者疼痛和疲倦的生理不适。根据不同的人口学特征实施不同的护理,从而提高胸外科术后患者的舒适度。     

Pharmacokinetics and drug interactions of antidepressive agents

Tricyclic antidepressive agents(TCAs) are conventional antidepressant. Cytochrome P450(CYP) 2D6 is involved in the hydroxylation of TCAs, while N-demethylation of TCAs is mediated by other such as CYP2C19, 3A4 and 1A2. The elimination of TCAs is impaired by CYP2D6 inhibitors such as quinidine. Newer antidepressants, selective serotonin uptake inhibitors(SSRIs), are also metabolized in the liver. Fluvoxamine, an SSRI, is a potent inhibitors for CYP1A2 and CYP2C19, moderate for CYP3A4 and weak for CYP 2D6. Paroxetine, another SSRI, causes substantial inhibition of CYP2D6 activity. Milnacipran, a serotonin and noradrenaline reuptake inhibitor, is mainly excreted unchanged in urine and some part as its glucronide conjugate. In contrast to many SSRIs, milnacipran is devoid of metabolic inhibition.     

Bacteriological sterility of washed deglycerolized red blood cells after 72 hours storage

Samples of reconstituted frozen red blood cells, maintained at 4 C for 72 hours prior to culture, revealed a bacterial contamination rate of less than 0.2 per cent, suggesting that the present shelf life of 24 hours may be safely extended to 72 hours.     

Pharmacokinetics of a once-daily regimen of lopinavir/ritonavir in HIV-1-infected children

INTRODUCTION: Lopinavir is an HIV protease inhibitor that is co-formulated with ritonavir. The approved paediatric dose is 230/57.5 mg/m2 twice daily. Once-daily dosing may offer an advantage to adherence. We studied the pharmacokinetics of lopinavir/ritonavir in a once-daily regimen in HIV-1-infected children. METHODS: HIV-1-infected children on stable antiretroviral therapy with a viral load <50 copies/ml for at least 6 months received lopinavir/ritonavir 460/115mg/m2 once daily with zidovudine and lamivudine. Blood samples were collected at 0, 2, 4, 6, 8, 12, 18 and 24 h after observed intake during steady state. Target level for lopinavir Cmin was 1.0 mg/l, based on in vitro IC50 data. RESULTS: Nineteen HIV-1-infected children with a median (range) age of 4.5 (1.4-12.9) years were enrolled. The median (interquartile range) dose of lopinavir was 456 (444-477) mg/m2. The mean (standard deviation) AUC0-24, Cmax and Cmin of lopinavir were 149.8 +/- 58.8 h*mg/l, 10.77 +/- 2.90 mg/l and 2.88 +/- 3.74 mg/l respectively. These values are comparable to data observed in adults using lopinavir/ritonavir 800/200 mg once daily. In 10/19 (53%) children Cmin was considered to be too low (<1.0 mg/l). Younger children more often experienced subtherapeutic trough levels. CONCLUSION: Our findings indicate that 460/115 mg/m2 lopinavir/ritonavir once daily leads to mean pharmacokinetic parameters comparable to data of 800/200 mg lopinavir/ritonavir once daily in adults, although the variability observed in the trough levels is much higher in children. Further research, especially in young children, is necessary to determine whether a higher dosage of lopinavir/ritonavir once daily must be given to reach the target level for Cmin.     

Smoking cessation: integration of behavioral and drug therapies

Family physicians should take advantage of each contact with smokers to encourage and support smoking cessation. Once a patient is identified as a smoker, tools are available to assess readiness for change. Using motivational interviewing techniques, the physician can help the patient move from the precontemplation stage through the contemplation stage to the preparation stage, where plans are made for the initiation of nicotine replacement and/or bupropion therapy when indicated. Continued motivational techniques and support are needed in the action stage, when the patient stops smoking. Group or individual behavioral counseling can facilitate smoking cessation and improve quit rates. Combined use of behavioral and drug therapies can dramatically improve the patient's chance of quitting smoking. A plan should be in place for recycling the patient through the appropriate stages if relapse should occur.     

Therapeutic drug monitoring of tobramycin: once-daily versus twice-daily dosage schedules

Objective: To evaluate the effect of dosage regimen (once-daily vs. twice-daily) of tobramicyn on steady-state serum concentrations and toxicity. Materials and methods: Patients undergoing treatment with iv tobramycin (4 mg/kg/day) were randomised to two groups. Group OD ( n=22) received a once-daily dose of tobramycin and group TD (n=21) received the same dose divided into two doses daily. Tobramycin serum concentrations (peak and trough) were measured by enzyme multiplied immunoassay. The renal and auditorory functions of the patients were monitored before, during and immediately after treatment. Results: The two groups were comparable with respect to sex, age, body weight and renal function. No statistically significant differences were found in mean daily dose, duration of treatment, or cumulative dose. Trough concentrations were < 2 μg/ml in the two groups (100%). Peak concentrations were > 6 μg/ml in 100% of the OD group and in 67% of the TD group ( P< 0·01). Mean peak concentrations were markedly different: 11·00±2·89 μg/ml in OD vs. 6·53±1·45 μg/ml in TD ( P< 0·01). The pharmacokinetics parameters were: K_e, (0·15±0·03/h in OD vs. 0·24±0·06/h in TD), t_1/2, (4·95±1·41 h in OD vs. 3·07±0·71 h in TD), V_d (0·35±0·11 l/kg in OD vs. 0·33±0·09 l/kg in TD), Cl (0·86±0·29 ml/min/kg in OD vs. 1·28±0·33 ml/min/kg in TD). Increased serum creatinine was observed in 73% of patients in OD versus 57% of patients in TD, without evidence of nephrotoxicity. In TD group, three patients developed decreased auditory function, of which one presented with an auditory loss of –30 dB, whereas in the OD group only one patient presented decreased auditory function. Conclusion: This small study suggests that a once-daily dosing regimen of tobramycin is at least as effective as and is no more and possibly less toxic than the twice-daily regimen. Using a single-dose therapy, peak concentration determination is not necessary, only trough samples should be monitored to ensure levels below 2 μg/ml.     

Pharmacokinetics and virological efficacy after switch to once-daily lopinavir-ritonavir in treatment-experienced HIV-1-infected children

Lopinavir-ritonavir (LPV/r) is a protease inhibitor that is used twice daily (BID) in the treatment of HIV infection in children. In the context of a single-center observational study, a switch to a once-a-day (QD) LPV/r regimen was proposed for considerations of convenience and to support adherence. The aims of this study were to compare the pharmacokinetics, viral loads, percentages of CD4(+) T cells, and lipid profiles after switching from a twice-daily to a once-daily regimen of LPV/r in experienced children. For this purpose, LPV concentrations, viral loads, CD4(+) T cells, and biochemistry data were measured in routine therapeutic drug monitoring procedures in 45 children and adolescents. Thirty-six children were switched to the QD regimen. Nine children on the BID or QD regimen were added for pharmacokinetic-study purposes only. The QD trough concentrations (C(trough)) of lopinavir in plasma were significantly lower than those observed with the BID regimen (P < 0.0001), but the 24-h exposure levels were not significantly lower with the QD than with the BID regimen (P = 0.09). Among 34 evaluable patients who switched from the BID to the QD regimen, the virological efficacy of LPV/r appeared to differ (P < 0.001), with 74% and 57% of viral loads, respectively, being <50 copies/ml (mean follow-up times, 33 and 20 months). Among 22 patients with stable virological control before the switch, 12 experienced either failure or blip (one observation of detectable viral load between two observations of undetectable viral load) after the switch. The change from the BID to the QD regimen did not result in significant differences in CD4(+) T cell percentages or total cholesterol, high-density lipoprotein (HDL) cholesterol, or triglyceride levels. The switch from the BID to the QD LPV/r regimen led to equivalent exposure and lower C(trough) values and resulted in lower levels of virological control in these antiretroviral-experienced children.