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2.
J Crit Care ; 30(1): 126-9, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25307975

ABSTRACT

BACKGROUND: Delirium is relatively common after lung transplantation, although its prevalence and prognostic significance have not been systematically studied. The purpose of the present study was to examine pretransplant predictors of delirium and the short-term impact of delirium on clinical outcomes among lung transplant recipients. METHODS: Participants underwent pretransplant cognitive testing using the Repeatable Battery for the Assessment of Neuropsychological Status and the Trail Making Test. After transplant, delirium was assessed using the Confusion Assessment Method until discharge. RESULTS: Sixty-three patients were transplanted between March and November 2013, of which 23 (37%) developed delirium. Among transplanted patients, 48 patients completed pretransplant cognitive testing. Better pretransplant cognitive function was associated with lower risk of delirium (odds ratio, 0.69 [95% confidence interval 0.48, 0.99], P = .043); and demographic and clinical features including native disease (P = .236), the Charlson comorbidity index (P = .581), and the lung allocation score (P = .871) were unrelated to risk of delirium, although there was a trend for women to experience delirium less frequently (P = .071). The presence (P = .006) and duration (P = .027) of delirium were both associated with longer hospital stays. CONCLUSION: Delirium occurs in more than one-third of patients after lung transplantation. Delirium was associated with poorer pretransplant cognitive functioning and longer hospital stays, after accounting for other medical and demographic factors.


Subject(s)
Cognition , Delirium/etiology , Length of Stay , Lung Transplantation/adverse effects , Adult , Aged , Confusion/diagnosis , Delirium/diagnosis , Delirium/epidemiology , Female , Humans , Male , Middle Aged , Neuropsychological Tests , Odds Ratio , Prevalence , Prognosis , Prospective Studies , Trail Making Test
3.
Am J Transplant ; 14(4): 849-56, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24666831

ABSTRACT

As HLAs antibody detection technology has evolved, there is now detailed HLA antibody information available on prospective transplant recipients. Determining single antigen antibody specificity allows for a calculated panel reactive antibodies (cPRA) value, providing an estimate of the effective donor pool. For broadly sensitized lung transplant candidates (cPRA ≥ 80%), our center adopted a pretransplant multi-modal desensitization protocol in an effort to decrease the cPRA and expand the donor pool. This desensitization protocol included plasmapheresis, solumedrol, bortezomib and rituximab given in combination over 19 days followed by intravenous immunoglobulin. Eight of 18 candidates completed therapy with the primary reasons for early discontinuation being transplant (by avoiding unacceptable antigens) or thrombocytopenia. In a mixed-model analysis, there were no significant changes in PRA or cPRA changes over time with the protocol. A sub-analysis of the median fluorescence intensity (MFI) change indicated a small decline that was significant in antibodies with MFI 5000-10,000. Nine of 18 candidates subsequently had a transplant. Posttransplant survival in these nine recipients was comparable to other pretransplant-sensitized recipients who did not receive therapy. In summary, an aggressive multi-modal desensitization protocol does not significantly reduce pretransplant HLA antibodies in a broadly sensitized lung transplant candidate cohort.


Subject(s)
Desensitization, Immunologic , Graft Rejection/prevention & control , Hypersensitivity/drug therapy , Immunoglobulins, Intravenous/therapeutic use , Isoantibodies/immunology , Lung Diseases/surgery , Lung Transplantation , Aged , Cohort Studies , Female , Follow-Up Studies , Graft Rejection/immunology , Graft Rejection/mortality , HLA Antigens/immunology , Humans , Immunoglobulins, Intravenous/immunology , Immunosuppressive Agents/therapeutic use , Lung Diseases/mortality , Male , Middle Aged , Plasmapheresis , Prognosis , Risk Factors , Survival Rate
4.
Am J Transplant ; 11(11): 2517-22, 2011 Nov.
Article in English | MEDLINE | ID: mdl-21883907

ABSTRACT

Primary graft dysfunction (PGD) after lung transplantation may result from ischemia reperfusion injury (IRI). The innate immune response to IRI may be mediated by Toll-like receptor and IL-1-induced long pentraxin-3 (PTX3) release. We hypothesized that elevated PTX3 levels were associated with PGD. We performed a nested case control study of lung transplant recipients with idiopathic pulmonary fibrosis (IPF) or chronic obstructive pulmonary disease (COPD) from the Lung Transplant Outcomes Group cohort. PTX3 levels were measured pretransplant, and 6 and 24 h postreperfusion. Cases were subjects with grade 3 PGD within 72 h of transplantation and controls were those without grade 3 PGD. Generalized estimating equations and multivariable logistic regression were used for analysis. We selected 40 PGD cases and 79 non-PGD controls. Plasma PTX3 level was associated with PGD in IPF but not COPD recipients (p for interaction < 0.03). Among patients with IPF, PTX3 levels at 6 and 24 h were associated with PGD (OR = 1.6, p = 0.02 at 6 h; OR = 1.4, p = 0.008 at 24 h). Elevated PTX3 levels were associated with the development of PGD after lung transplantation in IPF patients. Future studies evaluating the role of innate immune activation in IPF and PGD are warranted.


Subject(s)
C-Reactive Protein/metabolism , Idiopathic Pulmonary Fibrosis/surgery , Lung Transplantation/physiology , Primary Graft Dysfunction/etiology , Reperfusion Injury/complications , Serum Amyloid P-Component/metabolism , Adult , Case-Control Studies , Female , Humans , Idiopathic Pulmonary Fibrosis/physiopathology , Immunity, Innate , Lung Transplantation/adverse effects , Male , Middle Aged , Primary Graft Dysfunction/blood , Pulmonary Disease, Chronic Obstructive/physiopathology , Pulmonary Disease, Chronic Obstructive/surgery , Reperfusion Injury/immunology
5.
Diabetes Obes Metab ; 13(12): 1105-13, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21733060

ABSTRACT

AIMS: Davalintide is a second-generation amylinomimetic peptide possessing enhanced pharmacological properties over rat amylin to reduce food intake in preclinical models. The current experiments in rats describe additional glucoregulatory actions of davalintide consistent with amylin agonism, and explore the duration of action of these effects. METHODS: Subcutaneous (SC) injection of davalintide slowed gastric emptying with equal potency to amylin (ED50's = 2.3 and 4.1 µg/kg). This effect was maintained for 8 h with davalintide, but not amylin. Intraperitoneal injection of davalintide also reduced food intake with a potency similar to amylin (ED50's = 5.0 and 11.3 µg/kg). Consistent with amylin agonism, davalintide (10 µg/kg, SC) suppressed the plasma glucagon response over 90 min following an intravenous arginine bolus in anaesthetized rats. The elimination t(½) of davalintide (200 µg/kg, SC) was 26 min, similar to the t(½) of amylin, suggesting that pharmacokinetic-independent mechanisms contribute to davalintide's enhanced duration of action. Binding kinetic studies using ¹²5I davalintide revealed no appreciable dissociation from the amylin nucleus accumbens receptor after 7 h while ¹²5I rat amylin did dissociate from this receptor (K(off) = 0.013/min). Sustained SC infusion of davalintide (275 µg/kg/day) or amylin (300) decreased plasma glucose after an oral glucose challenge at 2 weeks (by 27 and 31%) and suppressed gastric emptying at 3 weeks (by 29 and 47%), demonstrating durable glucoregulatory actions of both peptides. CONCLUSIONS: These data show glucoregulatory properties of davalintide consistent with amylin agonism and suggest that slowed receptor dissociation plays a role in davalintide's prolonged pharmacodynamic actions.


Subject(s)
Appetite Depressants/pharmacology , Blood Glucose/drug effects , Glucagon/drug effects , Islet Amyloid Polypeptide/pharmacology , Peptides/pharmacology , Satiety Response/drug effects , Animals , Body Weight , Dose-Response Relationship, Drug , Eating , Gastric Emptying/drug effects , Injections, Subcutaneous , Male , Rats , Rats, Sprague-Dawley
6.
Transplant Proc ; 40(2): 494-7, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18374112

ABSTRACT

INTRODUCTION: Cystic fibrosis (CF) is an inherited disorder that presents in childhood as a multisystem disease. Pulmonary failure and pancreatic insufficiency, including CF-related diabetes (CFRD) and exocrine insufficiency, are significant causes of morbidity and mortality in these patients. In this report we have reviewed our experience with a simultaneous lung and pancreas transplantation in a patient with CF. METHODS: The recipient was a 25-year-old man with CF complicated by bronchiectasis with recurrent episodes of pneumonia, pancreatic exocrine insufficiency, and CFRD. He had normal hepatic and renal function. SURGICAL TECHNIQUE: The lung and pancreas allografts were procured from a single cadaveric donor. The double lung transplantation was performed through separate thoracic incisions. The pancreas transplantation was performed through a midline incision with systemic venous drainage and proximal enteric exocrine drainage. RESULTS: The recipient recovered well from his transplantation with early extubation. The pancreas allograft functioned well with normal blood glucose independent of insulin. As a result of the enteric drainage of the pancreas allograft, the patient no longer required supplemental pancreatic enzymes. His postoperative course was complicated by distal intestinal obstruction, a complex wound infection, and reversible leukoencephalopathy. At 1-year posttransplantation he remains free of supplemental oxygen, insulin, and pancreatic enzyme replacement. CONCLUSION: Simultaneous lung and pancreas transplantation in a patient with CF was performed safely, providing the advantages of normalization of glucose and improved nutrition for a patient requiring lung transplantation.


Subject(s)
Cystic Fibrosis/surgery , Lung Transplantation , Pancreas Transplantation , Adult , Cystic Fibrosis/complications , Humans , Lung Transplantation/methods , Male , Pancreas Transplantation/methods , Pulmonary Fibrosis/etiology , Pulmonary Fibrosis/surgery , Transplantation, Homologous/methods , Treatment Outcome
7.
Appl Occup Environ Hyg ; 16(6): 698-707, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11414520

ABSTRACT

Sampling and analytical methods were developed for commonly used chloroacetanilide, chlorotriazine, and 2,4-D herbicides in hand washes, on dermal patches, and in air. Eight herbicides selected for study were alachlor, atrazine, cyanazine, 2,4-dichlorophenoxyacetic acid (2,4-D), metolachlor, simazine, and two esters of 2,4-D, the 2-butoxyethyl ester (2,4-D, BE) and the 2-ethylhexyl ester (2,4-D, EH). The hand-wash method consisted of shaking the worker's hand in 150 mL of isopropanol in a polyethylene bag for 30 seconds. The dermal-patch method entailed attaching a 10-cm x 10-cm x 0.6-cm polyurethane foam (PUF) patch to the worker for exposure; recovery of the herbicides was achieved by extraction with 40 mL of isopropanol. The air method involved sampling with an OVS-2 tube (which contained an 11-mm quartz fiber filter and two beds of XAD-2 resin) and recovery with 2 mL of 10:90 methanol:methyl t-butyl ether. Analysis of each of the three sample types was performed by gas chromatography with an electron-capture detector. Diazomethane in solution was employed to convert 2,4-D as the free acid to the methyl ester in each of the three methods for ease of gas chromatography. Silicic acid was added to sample solutions to quench excess diazomethane. Limits of detection for all eight herbicides were matrix-dependent and, generally, less than 1 microgram per sample for each matrix. Sampling and analytical methods met NIOSH evaluation criteria for all herbicides in hand-wash samples, for seven herbicides in air samples (all herbicides except cyanazine), and for six herbicides in dermal-patch samples (all herbicides except cyanazine and 2,4-D). Speciation of 2,4-D esters and simultaneous determination of 2,4-D acid were possible without losses of the esters or of other herbicides (acetanilides and triazines) being determined.


Subject(s)
Environmental Monitoring/methods , Herbicides/analysis , Inhalation Exposure/analysis , Skin , 2,4-Dichlorophenoxyacetic Acid/analysis , Acetamides/analysis , Chromatography, Gas , Humans , Sensitivity and Specificity , Triazines
8.
J Biopharm Stat ; 10(3): 425-31, 2000 Aug.
Article in English | MEDLINE | ID: mdl-10959921

ABSTRACT

The United States Pharmacopeia requires that drug products meet established dissolution specifications throughout their shelf life. Whereas chemical stability for six months at accelerated storage conditions is generally regarded as providing a two-year expiry period, stress conditions are not considered predictive of dissolution stability at controlled room temperature. This paper presents an application of response surface methodology intended to incorporate the variability induced by storage temperature and relative humidity into robust product dissolution specifications. Contour plots, depicting one-sided tolerance limits of percent released, are presented as a function of crushing strength and dissolution time.


Subject(s)
Data Interpretation, Statistical , Drug Stability , Drug Storage/statistics & numerical data , Pharmaceutical Preparations/standards , Compressive Strength , Solubility , Tablets , Temperature
9.
J Laryngol Otol ; 112(8): 779-81, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9850324

ABSTRACT

Meningo-encephalocoeles of the skull base may present as spontaneous cerebrospinal fluid rhinorrhoea or acute meningitis. Previous approaches to midline skull base lesions have been either intracranial, via a craniotomy, or by transfacial or endoscopic extracranial approaches. This paper presents an alternative approach to lateral sphenoid sinus encephalocoeles through a Le Fort I osteotomy approach.


Subject(s)
Encephalocele/surgery , Meningocele/surgery , Sphenoid Sinus/diagnostic imaging , Encephalocele/diagnostic imaging , Encephalocele/pathology , Female , Humans , Magnetic Resonance Imaging , Maxilla/surgery , Meningocele/diagnostic imaging , Meningocele/pathology , Middle Aged , Osteotomy, Le Fort , Tomography, X-Ray Computed
10.
Arch Dis Child ; 78(3): 222-9, 1998 Mar.
Article in English | MEDLINE | ID: mdl-9613351

ABSTRACT

Growth and psychological functioning were studied in 30 patients with renal failure over a two year period following the offer of growth hormone treatment for significant short stature. Parents' concerns about growth decreased significantly during the study. Twenty eight parents (93%) accepted growth hormone treatment; most (74%) were satisfied with it and would opt for it again (89%). The views of these parents were unrelated to growth outcome in their child. This suggests that the positive responses were related more to the effort to improve growth than to any objective treatment success. In contrast children's reduction in concern about growth, satisfaction with treatment (36%), and decision to opt for growth hormone again (50%) were all significantly related to improvement in growth. Parents' reports of non-compliance increased significantly from 41% at 1 year to 91% at 2 years in the group as a whole. No significant changes were identified in maternal mental distress and no additional costs to the psychological health of the children seem to have resulted from the introduction of growth hormone treatment. A group of children was identified who accepted treatment but had continued poor growth. These appeared to be at particular risk of both physical problems and associated or consequent psychological difficulties.


Subject(s)
Child Behavior , Growth Disorders/drug therapy , Growth Disorders/etiology , Human Growth Hormone/therapeutic use , Kidney Failure, Chronic/complications , Adolescent , Adult , Body Height/drug effects , Child , Child, Preschool , Drug Administration Schedule , Family Health , Female , Growth Disorders/psychology , Human Growth Hormone/adverse effects , Humans , Longitudinal Studies , Male , Maternal Welfare , Patient Compliance , Self Concept
11.
Diabetes ; 46(11): 1859-67, 1997 Nov.
Article in English | MEDLINE | ID: mdl-9356037

ABSTRACT

Cardiovascular disease is excessive in diabetes, and blood cell function is altered. It is not clear, however, if alterations in the blood contribute to the excessive cardiovascular complications of this disease. In this study, we compared the contribution of nondiabetic and diabetic blood to myocardial reperfusion injury. The recovery of cardiac contractile function following no-flow ischemia was studied in isolated diabetic and nondiabetic rat hearts perfused with diabetic or nondiabetic diluted whole blood. Hearts were isolated from 10- to 12-week-old diabetic (streptozotocin, 65 mg/kg, i.v.) and nondiabetic rats and perfused with a Krebs-albumin-red cell solution (K2RBC, Hct 20%). After a 30-min pre-ischemic control period, during which cardiac pump function was evaluated, diabetic and nondiabetic hearts were perfused for 5 min with diluted whole blood (DWB; Hct 20%) collected from either diabetic or nondiabetic donor animals. Coronary flow was then stopped and the hearts subjected to 30 min of no-flow ischemia. Following ischemia, the hearts were reperfused with the K2RBC perfusate. Cardiac contractile function was evaluated throughout the 60-min reperfusion period. Six groups were studied: diabetic and nondiabetic hearts perfused before ischemia with either K2RBC, nondiabetic DWB (NDDWB), or diabetic DWB (DDWB). Perfusion with DWB prior to ischemia impaired the recovery of contractile function in all cases. The impairment to recovery was greater with DDWB than with NDDWB. Although diabetic hearts perfused with K2RBC throughout recovered quite well, the effect of DDWB perfusion in the diabetic hearts was dramatic. In an effort to determine why diabetic blood impaired functional recovery, measures of blood filterability and the generation of reactive oxygen species (ROS) were made. We found that diabetic blood was less filterable than nondiabetic blood; that is, the diabetic blood cells tended to plug the 5-microm filter pores more readily than the nondiabetic blood cells. Also, we found that the diabetic blood was capable of generating significantly greater ROS (oxygen free radicals) than nondiabetic blood (P < 0.05). These findings suggest that the blood contribution to myocardial reperfusion injury is amplified in diabetes. A tendency for diabetic blood cells to plug capillary-sized pores and show enhanced oxygen free radical production may account for the excessive contribution of diabetic blood to reperfusion injury in the heart.


Subject(s)
Diabetes Mellitus, Experimental/blood , Diabetes Mellitus, Experimental/physiopathology , Heart/physiology , Myocardial Contraction , Myocardial Ischemia/physiopathology , Myocardial Reperfusion Injury/blood , Myocardial Reperfusion Injury/physiopathology , Neutrophils/physiology , Animals , Body Weight , Coronary Circulation , Heart/physiopathology , In Vitro Techniques , Myocardial Ischemia/blood , Organ Size , Perfusion/instrumentation , Perfusion/methods , Rats , Rats, Wistar , Reactive Oxygen Species/metabolism , Ventricular Function, Left
12.
Am Ind Hyg Assoc J ; 58(10): 720-5, 1997 Oct.
Article in English | MEDLINE | ID: mdl-9342832

ABSTRACT

An air sampling and analytical method was developed for organonitrogen pesticides using a combined filter and XAD-2 sorbent sampler and high performance liquid chromatography-ultraviolet detection. The method was evaluated for 14 organonitrogen pesticides by National Institute for Occupational Safety and Health evaluation guidelines and procedures. Evaluation experiments addressed limits of detection and quantitation, analytical recovery, sampler capacity, sample stability, and precision and bias over a range of 12 to 240 micrograms per sample. Samples were stable when stored for up to 30 days under either ambient or refrigerated conditions. Based on the finding of this work, 10 of the 14 compounds studied (aldicarb, captan, carbaryl, carbofuran, chlorpropham, diuron, formetanate, methiocarb, oxamyl, propham) can be successfully determined simultaneously using one method with an accuracy of better than +/- 25% of the true value with 95% confidence. Two other compounds (carbendazim/benomyl, methomyl) can be measured with the same accuracy over a more limited concentration range. The remaining two compounds (propoxur, thiobencarb) may meet this criterion, but additional samples would need to be included in the data analysis. With the current data, these two compounds can be determined with an accuracy of better than +/- 27% of the true value with 95% confidence.


Subject(s)
Agricultural Workers' Diseases/prevention & control , Air Pollutants, Occupational/analysis , Environmental Monitoring/methods , Nitrogen Compounds/analysis , Pesticides/analysis , Chromatography, High Pressure Liquid , Humans , Reproducibility of Results
16.
J Pharm Sci ; 84(7): 815-8, 1995 Jul.
Article in English | MEDLINE | ID: mdl-7562429

ABSTRACT

The effects of dose on the serum and tissue kinetics of high and low molecular weight (M(r)) dextrans were studied in rats. Single intravenous (iv) doses of 1, 25, or 100 mg of fluorescein-labeled dextrans with average M(r) of approximately 4 kD (FD-4) or 150 kD (FD-150) per kilogram of body weight were administered to rats, and serum, urine, and various tissues were collected over time. The samples were analyzed by a sensitive and specific chromatographic method. For FD-150, the area under the serum concentration-time curves (AUCs) increased disproportionately when the dose was increased from 1 to 100 mg/kg; the dose-corrected AUCs were 50.1 +/- 1.9, 85.9 +/- 2.4, and 122 +/- 3 micrograms.h/mL for the doses of 1, 25, and 100 mg/kg, respectively (p < 0.05). This increase in the dose-corrected AUCs was associated with a high and nonlinear accumulation of FD-150 in the liver; that is, the percent dose recovered in the liver decreased from 68.5 +/- 2.4% to 41.5 +/- 3.4% when the dose was increased from 1 to 100 mg/kg (p < 0.05). On the other hand, the serum kinetics of FD-4 exhibited dose independence [the dose-corrected AUCs were 2.38 +/- 0.04, 2.19 +/- 0.07, and 2.30 +/- 0.07 microgram.h/mL for the doses of 1, 25, and 100 mg/kg, respectively (p > 0.05)]. This dose independence was attributed to a high and linear excretion of FD-4 into urine as indicated by the percent doses of FD-4 excreted into urine [i.e., 82.0 +/- 1.8, 78.7 +/- 4.4, and 82.2 +/- 7.2 for the doses of 1, 25, and 100 mg/kg, respectively (p > 0.05)].(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Dextrans/pharmacology , Dextrans/pharmacokinetics , Dose-Response Relationship, Drug , Animals , Injections, Intravenous , Kinetics , Liver/metabolism , Male , Molecular Weight , Rats , Rats, Sprague-Dawley , Spleen/metabolism , Time Factors , Tissue Distribution
17.
Arch Dis Child ; 73(1): 30-5, 1995 Jul.
Article in English | MEDLINE | ID: mdl-7639546

ABSTRACT

Issues raised by the recruitment of children to trials of growth hormone treatment for short stature in chronic renal failure are reported. Information needs of parents and children are discussed, the latter should take account of the children's developmental level and anticipated involvement in decision making. When the incidence of certain side effects is low and probably unquantifiable there are particular problems; failure to include these in information sheets may compromise informed consent but inclusion will, at least for some families, make an already difficult decision even more complicated. A process of recruitment is described which attempts to protect against bias and which balances the requirement to impart neutral information with appropriate clinical involvement in the decision to enter the study. Other functions of the recruitment process are identified. Analysis of understanding and decision making demonstrates that good understanding is neither necessary nor sufficient for ease of decision making. The recruitment process was time consuming and needs planning and funding in future studies. Many of these issues are of general importance for trials of treatment in children.


Subject(s)
Clinical Trials as Topic , Comprehension , Disclosure , Parental Consent , Patient Selection , Research Subjects , Risk Assessment , Therapeutic Human Experimentation , Adolescent , Child , Growth Disorders/drug therapy , Growth Disorders/etiology , Growth Hormone/administration & dosage , Humans , Informed Consent , Kidney Failure, Chronic/complications , Mental Competency , Parents
18.
Arch Dis Child ; 73(1): 36-42, 1995 Jul.
Article in English | MEDLINE | ID: mdl-7639547

ABSTRACT

Multicentre trials are evaluating growth hormone treatment in short children (height > 2 SDs below mean) with chronic renal failure (CRF), on dialysis, or with a transplant. Thirty children and parents from four centres were interviewed to assess psychological functioning and evaluate their concerns about growth in the context of CRF. There were 24 males and six females, age range 2-18 years. Fifty per cent of patients had additional non-renal complications and 30% had learning difficulties. Differences between the respective concerns of parents and children were striking. Parents' predominant concern was their child's future health (50%) and prospects (37%) while children's main concern was the impact of illness on their family (50%). Growth was a major concern for 30% of parents and 28% of children. Growth problems are important and should be considered within the context of other illness issues. Improved understanding of parental and child concerns may help maximise the benefits of growth hormone and assist in the management of children with CRF.


Subject(s)
Growth Disorders/etiology , Kidney Failure, Chronic/complications , Adolescent , Anxiety , Child , Child, Preschool , Clinical Trials as Topic , Cross-Sectional Studies , Family Health , Female , Growth Disorders/psychology , Humans , Kidney Failure, Chronic/psychology , Longitudinal Studies , Male , Parents
19.
Pharm Res ; 11(12): 1815-9, 1994 Dec.
Article in English | MEDLINE | ID: mdl-7899248

ABSTRACT

The kinetics of the individual enantiomers of verapamil (VER) and its metabolite, norverapamil (NOR), were studied in isolated perfused rat livers (IPRLs) after administration of racemic drug or the preformed metabolite. After constant infusion of 20 micrograms/min of racemic VER to single-pass IPRLs, the hepatic availabilities (F) of the enantiomers were low (S-VER, 0.069 +/- 0.030; R-VER: 0.046 +/- 0.025) and stereoselective (S:R ratio, 1.6 +/- 0.2). After administration of similar doses, the F values of the preformed NOR enantiomers (S-NOR: 0.24 +/- 0.04; R-NOR, 0.10 +/- 0.02) were higher than those of the VER enantiomers. However, the stereoselectivity in F of NOR (S:R ratio, 2.2 +/- 0.1), was in the same direction of that of VER. Further, the fractions of R enantiomers unbound to bovine serum albumin in the perfusate were higher than those of their antipodes for both VER (R:S ratio, 1.9 +/- 0.1) and NOR (R:S ratio, 2.6 +/- 0.2). Therefore, for unbound moieties, modest stereoselectivity in the metabolism of VER in favor of the S-isomer and no stereoselectivity in the metabolism of NOR were observed. Overall, our data suggest that the stereoselective protein binding is a primary determinant of stereoselectivity in the hepatic availability of VER and NOR in IPRLs.


Subject(s)
Liver/metabolism , Verapamil/analogs & derivatives , Verapamil/pharmacokinetics , Animals , Male , Metabolic Clearance Rate , Perfusion , Protein Binding , Rats , Rats, Sprague-Dawley , Stereoisomerism
20.
J Pharm Sci ; 83(10): 1495-9, 1994 Oct.
Article in English | MEDLINE | ID: mdl-7533835

ABSTRACT

The effects of molecular weight (M(r)) on the serum and urine pharmacokinetics and tissue distribution of dextrans, potential macromolecular carriers for drug delivery, were studied in rats. A single 5 mg/kg dose of fluorescein-labeled dextrans (FDs) with a M(r) of 4000 (FD-4), 20,000 (FD-20), 70,000 (FD-70), or 150,000 (FD-150) was administered into the tail vein of separate groups of rats. At different times after the administration of each FD, animals were sacrificed, and blood, urine, and various tissues were obtained. The concentrations of FDs in the samples were subsequently determined by using a sensitive and specific high performance size exclusions chromatographic method. Among the tissues studied, high accumulation of dextrans was found only in the liver (liver:serum AUC ratios < or = 29) and spleen (spleen:serum AUC ratios < or = 10), with high concentrations in these tissues persisting even at the last sampling time (96 h). In contrast, the serum concentrations of the studied FDs were not measurable beyond 12 h. The serum and urine kinetics and the liver, spleen, and kidney accumulation of FDs demonstrated a significant degree of M(r) dependency. The total and renal clearance of FDs consistently decreased with an increase in M(r). However, the effects of M(r) on the tissue accumulation of dextrans was tissue dependent. For the liver, the tissue:serum AUC ratios increased from 0.346 for FD-4 to 15.2 for FD-20 and 28.8 for FD-70, while a further increase in M(r) to 150 kDa (FD-150) resulted in lowering the ratio to 8.59 in this tissue. For the spleen, the ratios increased from 0.095 for FD-4 to 9.56 for FD-150.(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Dextrans/pharmacokinetics , Animals , Dextrans/blood , Dextrans/urine , Liver/metabolism , Male , Molecular Weight , Rats , Rats, Sprague-Dawley , Spleen/metabolism , Time Factors , Tissue Distribution
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