Over-the-Counter Medications in Cardiac Transplant Recipients: Guidelines for Use

OBJECTIVE:

The purpose of this article is to review the pathophysiology of the denervated heart and the factors that need to be considered before recommending the use of over-the-counter (OTC) medications in the cardiac transplant recipient.

DATA SOURCES:

Pharmacology and therapeutic textbooks, English-language journal articles, and physiology textbooks published between 1969 and 1991.

DATA EXTRACTION:

Case reports, controlled case studies, and textbook chapters evaluating drug interactions with immunosuppressive agents were reviewed. The effects of various OTC medications on the denervated heart were examined and relevant material was extrapolated.

DATA ANALYSIS:

The number of cases or studies in which a particular effect or interaction occurred was reported. Those findings that were less well documented were either identified as such or were not included in the review.

DATA SYNTHESIS:

Common pharmacokinetic and pharmacodynamic interactions with the primary immunosuppressive agents (e.g., cyclosporine, azathioprine, prednisone) are reviewed. The physiology and altered responses of the denervated heart to various medications are also explained. Using this information, recommendations are given for the use and monitoring of OTC analgesics, antacids, laxatives, sleep aids, stimulants, and other medications that may be used in the cardiac transplant recipient.

CONCLUSIONS:

Many OTC medications can be used safely in the cardiac transplant recipient. In each situation, risk/benefit assessments must always be made and therapy should be monitored closely. Most important, patients should always notify the transplant team before adding an OTC product to their immunosuppressive regimen.

Pharmacokinetic monitoring of mycophenolic acid in heart transplant patients: correlation the side-effects and rejections with pharmacokinetic parameters

BACKGROUND

Mycophenolate mofetil is a commonly used immunosuppressant in heart transplantation but pharmacokinetic monitoring is not routinely done. We performed a prospective pilot multi-center trial in de-novo heart transplant recipients to evaluate the pharmacokinetics (PK) of mycophenolic acid (MPA) at multiple time points in the first year following transplant.<br />

MATERIAL/METHODS

MPA trough and estimated area-under-the-curve (AUC) values were obtained at multiple visits from 21 enrolled patients. We attempted to correlate the side-effects and rejections with PK parameters.<br />

RESULTS

MPA AUC and trough levels increased modestly over 12 months with substantial inter and intra patient variability. Cardiac rejection was associated with low MPA AUC values with a threshold of <36.2 mg×h/L during the first two post-transplant weeks. A threshold of 2-weeks average MPA trough level of 1.43 mg/L provided a sensitivity 82% and a specificity of 60%.<br />

CONCLUSIONS

Adequate MPA levels are associated with decreased risk of allograft rejection. For patients with Cyclosporine co-immunosuppression, we propose an MPA trough of 1.4 mg/L and an MPA AUC of 36 mg × h/L as threshold values for dose adjustments. We recommend monitoring MPA levels at 1, 2 and 4 weeks, 6 months, 1 year and whenever an unexplained side-effect or allograft rejection occurs. Additional MPA AUC measurements are recommended when trough levels do not explain the clinical picture.<br />

Impact of changing from cyclosporine to tacrolimus on pharmacokinetics of mycophenolic acid in renal transplant recipients with diabetes

The rate of mycophenolic acid (MPA) absorption after oral administration of mycophenolate mofetil (MMF) is delayed in patients with diabetes. Cyclosporine (CsA) decreases MPA exposure by inhibiting enterohepatic recirculation of MPA/MPA glucuronide, and tacrolimus (TRL) may alter the rate and extent of MPA absorption due to its prokinetic properties especially in patients with diabetic gastroparesis. This study evaluated the effect of changing from CsA to TRL on pharmacokinetics of MPA in stable renal transplant recipients with long-standing diabetes. Eight patients were switched from a stable dose of CsA to TRL while taking MMF 1 g twice daily. The 12-hour steady-state total plasma concentration-time profiles of MPA and MPA glucuronide were obtained after oral administration of MMF on 2 occasions: first while taking CsA and second after changing to TRL. Pharmacokinetic parameters of MPA were calculated by the noncompartmental method. Changing from CsA to TRL resulted in significantly increased MPA exposure (area under the concentration-time curve from 0 to 12 hours, AUC0-12) by 46 +/- 32% (P = 0.012) and MPA predose concentration (C0) by 121 +/- 67% (P = 0.008). The magnitude of change in MPA exposure did not correlate well with MPA-C0 or CsA trough concentration. Switching to TRL had minimal impact on peak concentration of MPA (15.0 +/- 6.9 mg/L with CsA versus 16.1 +/- 9.7 mg/L with TRL, P = 0.773) and time to reach the peak concentration (1.0 +/- 0.4 hours with CsA versus 1.2 +/- 0.8 hours with TRL, P = 0.461). Highly variable and unpredictable changes in MPA exposure among renal transplant patients with diabetes do not support a strategy of preemptively adjusting MMF dose when switching calcineurin inhibitors in this population.

Lack of an Effect of Oral Iron Administration on Mycophenolic Acid Pharmacokinetics in Stable Renal Transplant Recipients

STUDY OBJECTIVES

To determine if coadministration of polysaccharide iron complex and slow-release ferrous sulfate alter the absorption of mycophenolic acid (MPA), and to examine the potential influence of dosing relative to mycophenolate mofetil (MMF) administration and the effect of immediate- versus sustained-release iron products on the steady-state pharmacokinetics of MPA.

DESIGN

Prospective, open-label, three-phase, crossover, steady-state pharmacokinetic study.

SETTING

National Institutes of Health-sponsored General Clinical Research Center at a university medical center.

PATIENTS

Twelve adult (mean age 50 yrs) renal transplant recipients who were receiving concomitant iron and MMF maintenance therapy.

INTERVENTION

Oral iron therapy was coadministered with MMF on days -6-0, MMF was administered alone on days 1-8 (control phase), then oral iron therapy was administered 2 hours after MMF administration on days 9-16.

MEASUREMENTS AND MAIN RESULTS

Baseline demographics, concurrent drug regimens, and clinical laboratory values were assessed. Blood samples were obtained at baseline and at 1, 2, 3, 4, 6, 8, and 12 hours after MMF administration on days 0, 8, and 16. The MPA levels were measured by high-performance liquid chromatography. We found no significant differences in the dose-standardized area under the concentration-time curve from 0-12 hours (AUC(0-12)) for MPA between the control phase (39.66 +/- 8.70 mg mg x hr/L) and the concomitant ferrous sulfate or dose-separated ferrous sulfate (37.56 +/- 9.95 or 32.84 +/- 8.43 mg x hr/L, respectively, p>0.05) phases. Dose-standardized AUC(0-12) values for MPA did not significantly differ after the concomitant administration of polysaccharide iron complex from that of the control phase (48.46 +/- 9.68 and 43.80 +/- 9.46 mg x hr/L, respectively, p=0.065). However, the AUC(0-12) for MPA significantly increased when polysaccharide iron complex was administered 2 hours after MMF (53.41 +/- 11.75 mg x hr/L, p=0.012). Maximum concentrations and times to reach maximum concentrations remained consistent across all study phases in each arm of the trial (p>0.05).

CONCLUSION

Multiple doses of iron therapy-slow-release ferrous sulfate, or polysaccharide iron complex-did not significantly reduce systemic exposure to MMF, as measured by using AUC(0-12) values.

Rabbit antithymocyte globulin versus basiliximab in renal transplantation

BACKGROUND

Induction therapy reduces the frequency of acute rejection and delayed graft function after transplantation. A rabbit antithymocyte polyclonal antibody or basiliximab, an interleukin-2 receptor monoclonal antibody, is most commonly used for induction.

METHODS

In this prospective, randomized, international study, we compared short courses of antithymocyte globulin and basiliximab in patients at high risk for acute rejection or delayed graft function who received a renal transplant from a deceased donor. Patients taking cyclosporine, mycophenolate mofetil, and prednisone were randomly assigned to receive either rabbit antithymocyte globulin (1.5 mg per kilogram of body weight daily, 141 patients) during transplantation (day 0) and on days 1 through 4 or basiliximab (20 mg, 137 patients) on days 0 and 4. The primary end point was a composite of acute rejection, delayed graft function, graft loss, and death.

RESULTS

At 12 months, the incidence of the composite end point was similar in the two groups (P=0.34). The antithymocyte globulin group, as compared with the basiliximab group, had lower incidences of acute rejection (15.6% vs. 25.5%, P=0.02) and of acute rejection that required treatment with antibody (1.4% vs. 8.0%, P=0.005). The antithymocyte globulin group and the basiliximab group had similar incidences of graft loss (9.2% and 10.2%, respectively), delayed graft function (40.4% and 44.5%), and death (4.3% and 4.4%). Though the incidences of all adverse events, serious adverse events, and cancers were also similar between the two groups, patients receiving antithymocyte globulin had a greater incidence of infection (85.8% vs. 75.2%, P=0.03) but a lower incidence of cytomegalovirus disease (7.8% vs. 17.5%, P=0.02).

CONCLUSIONS

Among patients at high risk for acute rejection or delayed graft function who received a renal transplant from a deceased donor, induction therapy consisting of a 5-day course of antithymocyte globulin, as compared with basiliximab, reduced the incidence and severity of acute rejection but not the incidence of delayed graft function. Patient and graft survival were similar in the two groups. (ClinicalTrials.gov number, NCT00235300 [ClinicalTrials.gov].).

Efficacy and safety of low-dose valganciclovir in the prevention of cytomegalovirus disease in adult liver transplant recipients

The efficacy and safety of valganciclovir (VGCV) for cytomegalovirus (CMV) prophylaxis in liver transplant recipients has not been established. We retrospectively compared the efficacy and safety of low-dose oral VGCV (450 mg once daily for 90 days) and standard oral ganciclovir (1 g three times a day for 90 days, GCV) in preventing CMV disease in 109 adult liver transplant recipients who survived at least 1 month between January 2001 and April 2003 (49 GCV and 60 VGCV). The incidence of CMV disease at 1 year post-transplant was similar among patients treated with VGCV and GCV (3% and 4%, respectively). Three of the four CMV disease cases occurred in high-risk recipients with CMV serotype of donor+/recipient- (D+/R-) and all cases presented after completion of CMV prophylaxis, ranging 114-152 days post-transplant. Severe neutropenia was rare, and thrombocytopenia and anemia occurred at similar frequencies with both prophylaxis regimens. In conclusion, a 90-day regimen of low-dose oral VGCV has a similar efficacy and safety profile to high-dose oral GCV in adult liver transplant recipients. D+/R- liver transplant recipients remain at risk of developing CMV disease after completion of antiviral prophylaxis. Additional prospective studies with close monitoring for CMV viremia and drug resistance are needed to further establish the optimal dose and duration of VGCV in liver transplant recipients.

Effect of Oral Vitamin E and C Therapy on Calcineurin Inhibitor Levels in Heart Transplant Recipients

BACKGROUND

A recent prospective trial demonstrated that oral vitamins C and E retard the early progression of transplant-associated coronary arteriosclerosis; as a result, a number of centers have added these agents to their maintenance regimens. This study reviewed the impact of vitamin E and C supplementation on calcineurin inhibitor trough concentrations.

METHODS

A retrospective chart review of the first 29 heart transplant patients prescribed anti-oxidant agents was performed. Twenty-two patients taking cyclosporin A (CsA) and 7 patients taking tacrolimus were prescribed vitamin C (500 mg twice a day) and vitamin E (400 IU twice a day). Serum chemistries and drug levels were measured before and after vitamin therapy was initiated.

RESULTS

The baseline CsA trough concentration (mean +/- SD) was 137 +/- 39 ng/ml and it declined to 99 +/- 54 ng/ml (p = 0.007) after anti-oxidant therapy was initiated. The average percentage decrease in the CsA trough concentration was 30%. No significant changes were seen in the patients taking tacrolimus.

CONCLUSIONS

These data demonstrate that supplementation with the anti-oxidant agents vitamin C and vitamin E decreases CsA concentrations but does not appear to effect tacrolimus concentrations. Although more detailed pharmacokinetic analysis is necessary to clarify the exact mechanism of this interaction, physicians who take care of transplant recipients should be aware that more frequent CsA concentration monitoring is warranted after initiating these anti-oxidant agents.

Reproduction and transplantation: report on the AST Consensus Conference on Reproductive Issues and Transplantation

It has been almost 50 years since the first child was born to a female transplant recipient. Since that time pregnancy has become common after transplantation, but physicians have been left to rely on case reports, small series and data from voluntary registries to guide the care of their patients. Many uncertainties exist including the risks that pregnancy presents to the graft, the patient herself, and the long-term risks to the fetus. It is also unclear how to best modify immunosuppressive agents or treat rejection during pregnancy, especially in light of newer agents available where pregnancy safety has not been established. To begin to address uncertainties and define clinical practice guidelines for the transplant physician and obstetrical caregivers, a consensus conference was held in Bethesda, Md. The conferees summarized both what is known and important gaps in our knowledge. They also identified key areas of agreement, and posed a number of critical questions, the resolution of which is necessary in order to establish evidence-based guidelines. The manuscript summarizes the deliberations and conclusions of the conference as well as specific recommendations based on current knowledge in the field.

Statin use and risks of death or fatal rejection in the Heart Transplant Lipid Registry

Although small, randomized trials have shown that statin use is associated with decreased risks of mortality and severe rejection, no study has examined statin therapy as used in actual practice in large numbers of heart transplant recipients. We analyzed data from the Heart Transplant Lipid Registry (n = 12 centers). Patients were included if they underwent transplantation between 1995 and 1999, survived >/=30 days after transplantation, and had >/=30 days of Registry follow-up. Multivariable Cox regression models, with propensity scoring performed to adjust for nonrandom allocation of statin therapy, were performed to determine the association of statin therapy with death and fatal rejection. The study included 1,186 patients, with a mean follow-up of 580 +/- 469 days; 937 patients (79%) received statin therapy. Overall, 71 patients (6%) died and 40 (3.4%) had fatal rejection. The statin group had a lower frequency of death (4% vs 13.7%, p <0.0001) and fatal rejection (2.4% vs 7.2%, p = 0.0001). Using multivariable Cox regression, with propensity scoring included to adjust for likelihood of receiving statin therapy, statin use was the only factor associated with lower risk of death (hazard ratio 0.29, 95% confidence interval 0.13 to 0.67) and fatal rejection (hazard ratio 0.27, 95% confidence interval 0.09 to 0.78). This study represents the largest population of heart transplant recipients analyzed for the relation between statin therapy and clinical outcomes in actual practice. Statin therapy was significantly associated with lower risk of death and fatal rejection, benefits that were independent of lipid values.

Lack of correlation between MMF dose and MPA level in pediatric and young adult cardiac transplant patients: does the MPA level matter?

To determine the correlation between mycophenolate mofetil (MMF) dose and mycophenolic acid (MPA) level as well as its impact on rejection among young cardiac transplant recipients (OHT), trough concentrations of MPA and its metabolite, mycophenolic acid glucuronide (MPAG), were measured following MMF doses of 1200 mg/m2/d (max 3000 mg/d). Corresponding endomyocardial biopsy (EMB) grades and calcineurin inhibitor levels were recorded with simultaneous MPA/MPAG levels. Correlation coefficients were derived between MMF dose and MPA/MPAG levels. Contingency analysis evaluated the relation between MPA level and EMB score. Twenty-six patients (median age 15.4 years) had 120 MPA/MPAG levels measured. Average MMF dose was 1208.8 mg/m2/d with median MPA and MPAG concentrations: 2.1 (therapeutic: 1.0-3.5 microg/mL) and 48 microg/mL (reference range: 35-100 microg/mL), respectively. Only 50% of patients consistently achieved therapeutic levels with standard dosing. No correlation was found between MMF dose and MPA/MPAG levels. In the presence of therapeutic calcineurin inhibition, EMB grade > or = 2 occurred more with MPA concentrations < 2.5 microg/mL (p = 0.01). In young OHT patients, MMF dose does not correlate with MPA/MPAG levels, and standard MMF dosing fails to consistently achieve 'therapeutic' MPA concentrations. An MPA trough level < 2.5 microg/mL was more frequently associated with EMB grade > or = 2. Concentration rather than dose-driven management is a more prudent strategy when using MMF.

New prophylactic treatment strategy for cytomegalovirus disease

The pharmacology, pharmacokinetics, safety, and efficacy of valganciclovir, an oral prodrug for ganciclovir, used to prevent cytomegalovirus (CMV) disease in solid organ transplant recipients are described. Valganciclovir was developed to overcome the disadvantages associated with ganciclovir, which include low oral bioavailability, limited efficacy because of the development of viral resistance, and the need for frequent administration, which can adversely affect patient adherence. Valganciclovir is rapidly converted to ganciclovir; systemic exposure to the parent drug is low and short in duration. The oral bioavailability of ganciclovir from valganciclovir is 10 times higher than that from the original ganciclovir formulation. Food increases the oral bioavailability of valganciclovir. In a four-way, randomized, crossover pharmacokinetic study of 28 liver transplant recipients, single doses of valganciclovir 900 mg and intravenous ganciclovir 5 mg/kg resulted in a similar ganciclovir systemic exposure. The systemic exposure was proportionately lower with a single 450-mg dose of valganciclovir but similar to that of oral ganciclovir 3 g administered in three divided doses. In the recent multicenter, randomized, double-blind, double-dummy PV16000 trial in 364 solid organ transplant recipients at high risk for CMV disease (i.e., CMV-negative recipients of CMV-positive donor organs), valganciclovir 900 mg once daily was as effective in preventing CMV-disease as oral ganciclovir 1 g three times daily. Resistance was reported with ganciclovir but not with valganciclovir. Both drugs were well tolerated.

Safety and efficacy of atorvastatin in heart transplant recipients

BACKGROUND

Pravastatin and simvastatin prolong survival and reduce transplant-related coronary vasculopathy, although low-density lipoprotein (LDL) lowering with these agents is only modest. The objective of this study was to assess the safety of moderate dose atorvastatin and its efficacy when prior treatment with another statin had failed to lower LDL to < 100 mg/dl.

METHODS

Data from 185 patients were retrospectively evaluated for adverse events, duration of exposure (person-days), and the mean atorvastatin dose exposure. Changes in lipid parameters, and prednisone and cyclosporine doses were determined.

RESULTS

SAFETY

48 patients received atorvastatin for 24,240 person-days at a mean dose exposure of 21 +/- 10 mg. Rhabdomyolysis, myositis, myalgias, and hepatotoxicity occurred in 0, 2, 2, and 0 patients, respectively. All events occurred at the 10-mg dose, within the first 3 months, and were rapidly reversible with atorvastatin discontinuation.

EFFICACY

Thirty-four patients evaluable for efficacy analyses had a pre-atorvastatin LDL of 145 +/- 38 mg/dl on the following statins: pravastatin (n = 30, 40 +/- 0mg), fluvastatin (n = 3, 33 +/- 12 mg), simvastatin (n = 1, 40 mg). After atorvastatin (21 +/- 9 mg/day) for 133 +/- 67 days, LDL was reduced to 97 +/- 24 mg/dl (relative reduction 31 +/- 20%, p < 0.0001). At the end of the observation period (418 +/- 229 days, atorvastatin final dose 24 +/- 14 mg/day), LDL was further decreased to 88 +/- 23 mg (relative reduction 37 +/- 17%, p < 0.0001).

CONCLUSION

Atorvastatin, when used at moderate doses and with close biochemical and clinical monitoring, appears to be safe and is effective in aggressively lowering LDL in heart transplant recipients when treatment with other statins has failed to achieve LDL goals.

A retrospective assessment of safety, efficacy, and pharmacoeconomics of generic azathioprine in heart-transplant recipients

Although a generic formulation of azathioprine (AZA) has been available since 1996, safety, efficacy and pharmacoeconomic implications following conversion from Imuran (AZA) to generic AZA in heart-transplant patients remains to be determined. A retrospective, safety and efficacy assessment, in addition to a cost comparison, was performed in 30 heart-transplant patients who had been switched from Imuran to generic AZA. In heart-transplant patients converted from Imuran to generic AZA, no compromise in safety and efficacy, as measured by white blood cell (WBC) count, infections, rejections, malignancies, and hospitalizations was observed. Generic substitution of Imuran results in an annual cost savings of $318 per patient.

Immunosuppressive Drugs and Novel Strategies to Prevent Acute and Chronic Allograft Rejection

Maintenance immunosuppression for lung transplantation includes cyclosporine or tacrolimus, mycophenolate mofetil or azathioprine, and prednisone. Some centers rely on induction agents including OKT3 (murine monoclonal antibody, OKT3), ATG (antithymocyte globulin), or thymoglobulin. In addition, a number of new agents including sirolimus (SRL) and the interleukin (IL)-2 receptor antagonists, daclizumab and basiliximab, have become available. Management of chronic rejection typically consists of augmented immunosuppression using many of the standard agents, and other potent agents such as methotrexate or cytoxan or more novel strategies including photopheresis, radiation, and total lymphoid irradiation (TLI).

Elevated free fractions of valproic acid in a heart transplant patient with hypoalbuminemia

OBJECTIVE

To report a case demonstrating the importance of monitoring unbound valproic acid (VPA) serum concentrations in a patient with hypoalbuminemia.

CASE SUMMARY

A 53-year-old white woman status-post heart transplantation was admitted to the hospital for declining cardiac function, possible rejection, and increased lethargy requiring intubation. An extensive workup of the patient's profound lethargy was initiated, including an evaluation of her VPA regimen. Initially, VPA dosages were adjusted based on the total serum concentration of VPA. Hypoalbuminemia compounded with increased lethargy prompted the measurement of unbound serum concentrations of VPA. The VPA dosage was then adjusted based on the unbound rather than the total VPA serum concentration; the patient eventually improved and was discharged from the hospital.

DISCUSSION

Lethargy is a concentration-related adverse effect of VPA. The nonlinear pharmacokinetic and protein saturation characteristics of VPA may result in nonproportional elevations in unbound drug, and subsequent increases in adverse effects, when dosage adjustments are based solely on measurement of total VPA serum concentrations in patients with hypoalbuminemia.

CONCLUSIONS

This case report suggests that appropriate monitoring of unbound drug concentrations of VPA may prevent unrecognized concentration-related adverse effects. Awareness of the pharmacokinetic relationship and adverse effects of VPA will aid clinicians in identifying the etiology of symptoms.

Cannabinoid-induced mesenteric vasodilation through an endothelial site distinct from CB1 or CB2 receptors

Cannabinoids, including the endogenous ligand arachidonyl ethanolamide (anandamide), elicit not only neurobehavioral but also cardiovascular effects. Two cannabinoid receptors, CB1 and CB2, have been cloned, and studies with the selective CB1 receptor antagonist SR141716A have implicated peripherally located CB1 receptors in the hypotensive action of cannabinoids. In rat mesenteric arteries, anandamide-induced vasodilation is inhibited by SR141716A, but other potent CB1 receptor agonists, such as HU-210, do not cause vasodilation, which implicates an as-yet-unidentified receptor in this effect. Here we show that "abnormal cannabidiol" (Abn-cbd) is a neurobehaviorally inactive cannabinoid that does not bind to CB1 receptors, yet causes SR141716A-sensitive hypotension and mesenteric vasodilation in wild-type mice and in mice lacking CB1 receptors or both CB1 and CB2 receptors. Hypotension by Abn-cbd is also inhibited by cannabidiol (20 microgram/g), which does not influence anandamide- or HU-210-induced hypotension. In the rat mesenteric arterial bed, Abn-cbd-induced vasodilation is unaffected by blockade of endothelial NO synthase, cyclooxygenase, or capsaicin receptors, but it is abolished by endothelial denudation. Mesenteric vasodilation by Abn-cbd, but not by acetylcholine, sodium nitroprusside, or capsaicine, is blocked by SR141716A (1 microM) or by cannabidiol (10 microM). Abn-cbd-induced vasodilation is also blocked in the presence of charybdotoxin (100 nM) plus apamin (100 nM), a combination of K(+)-channel toxins reported to block the release of an endothelium-derived hyperpolarizing factor (EDHF). These findings suggest that Abn-cbd and cannabidiol are a selective agonist and antagonist, respectively, of an as-yet-unidentified endothelial receptor for anandamide, activation of which elicits NO-independent mesenteric vasodilation, possibly by means of the release of EDHF.

Nefazodone and cyclosporine drug-drug interaction

Depression is a significant post-transplant complication often necessitating drug therapy. Many of the newer selective serotonin reuptake inhibitor (SSRI) antidepressants are metabolized by the same cytochrome P450IIIA isoenzyme system that is responsible for the metabolism of cyclosporine, and these agents pose an interactive risk in transplant patients. We have observed nearly a 10-fold increase in whole blood cyclosporine concentrations in a cardiac transplant patient shortly after the addition of nefazodone antidepressant therapy. We suggest there is a clinically significant drug-drug interaction between nefazodone and cyclosporine due to inhibition of cytochrome P-450 IIIA4 isoenzymes by nefazodone.

Adenovirus-mediated gene transfer in vivo to cerebral blood vessels and perivascular tissue in mice

BACKGROUND AND PURPOSE

Gene transfer to cerebral blood vessels has been accomplished in rats and dogs by injection of replication-deficient adenovirus into cerebrospinal fluid. In this study we examined transgene expression after injection of adenovirus into the cerebrospinal fluid of mice. Responses were observed in ICR mice and C57BL/6 mice, which are outbred and inbred strains, respectively.

METHODS

We injected replication-deficient recombinant adenovirus expressing nuclear targeted beta-galactosidase, driven by either the Rous sarcoma virus promoter (AdRSV-betaGal) or the cytomegalovirus promoter (AdCMV-betaGal), into the cisterna magna of anesthetized ICR and C57BL/6 strains of mice. The brains were examined from 1 to 21 days after injection by chemiluminescent enzyme activity assay or histochemical staining.

RESULTS

After injection of AdRSV-betaGal, expression of beta-galactosidase in ICR mice peaked on day 7 and returned to basal by day 14. Expression of beta-galactosidase in C57BL/6 mice was maximal on days 7 to 14 and was minimal by day 21 after injection of AdRSV-betaGal. After injection of AdCMV-betaGal in C57BL/6 mice, peak expression of transgene occurred on day 1 and was greatly diminished by day 3. Transgene expression was observed primarily on the ventral surface of the brain, with preferential expression in leptomeninges and adventitia along the major cerebral arteries of that region.

CONCLUSIONS

Injection of recombinant adenovirus in the cisterna magna resulted in transgene expression in leptomeninges and perivascular tissue of cerebral blood vessels in two strains of mice. The CMV promoter elicited rapid but short-lived expression of the transgene, while the RSV promoter elicited slower, more sustained transgene expression. Expression of AdRSV transgene was prolonged in C57BL/6 mice compared with ICR mice. This approach for gene transfer may be useful to study cerebral vascular biology in genetically altered strains of mice.

Policies regarding the transplantation of hepatitis C-positive candidates and donor organs

Whether hepatitis C virus (HCV)-positive candidates or donor organs should undergo transplantation remains controversial. Seventy-two thoracic transplantation centers responded to a survey soliciting specific information about policies regarding the listing of HCV-positive candidates and the use of HCV-positive donor organs. Most centers (64%) list HCV-positive candidates for heart transplantation. Twenty-six percent of centers refuse to use HCV-positive organs, whereas the remainder restrict the use of HCV-positive organs to status 1 recipients or HCV-positive candidates. More information is needed regarding the clinical outcomes of HCV-positive candidates and recipients of HCV-positive organs before clear-cut candidate selection and organ allocation policies can be established.

Cannabinoid-induced hypotension and bradycardia in rats mediated by CB1-like cannabinoid receptors

Previous studies indicate that the CB1 cannabinoid receptor antagonist, N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-met hyl-1H-pyrazole-3-carboxamide HCl (SR141716A), inhibits the anandamide- and delta9-tetrahydrocannabinol- (THC) induced hypotension and bradycardia in anesthetized rats with a potency similar to that observed for SR141716A antagonism of THC-induced neurobehavioral effects. To further test the role of CB1 receptors in the cardiovascular effects of cannabinoids, we examined two additional criteria for receptor-specific interactions: the rank order of potency of agonists and stereoselectivity. A series of cannabinoid analogs including the enantiomeric pair (-)-11-OH-delta9-THC dimethylheptyl (+)-11-OH-delta9-THC dimethylheptyl were evaluated for their effects on arterial blood pressure and heart rate in urethane anesthetized rats. Six analogs elicited pronounced and long lasting hypotension and bradycardia that were blocked by 3 mg/kg of SR141716A. The rank order of potency was (-)-11-OH-delta9-THC dimethylheptyl > or = (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol > (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol > THC > anandamide > or = (-)-3-[2-hydroxy-4-(1,1-dimethyl-heptyl)phenyl]-4-[3-hydroxy-propyl]c yclohexan-1-ol, which correlated well with CB1 receptor affinity or analgesic potency (r = 0.96-0.99). There was no hypotension or bradycardia after palmitoylethanolamine or (+)-11-OH-delta9-THC dimethylheptyl. An initial pressor response was also observed with THC and anandamide, which was not antagonized by SR141716A. We conclude that the similar rank orders of potency, stereoselectivity and sensitivity to blockade by SR141716A indicate the involvement of CB1-like receptors in the hypotensive and bradycardic actions of cannabinoids, whereas the mechanism of the pressor effect of THC and anandamide remains unclear.

Cardiovascular effects of anandamide in anesthetized and conscious normotensive and hypertensive rats

We previously showed that in anesthetized rats anandamide elicits bradycardia and a triphasic blood pressure response: transient hypotension secondary to a vagally mediated bradycardia, followed by a brief pressor and prolonged depressor response, the latter two effects being similar to those of delta 9-tetrahydrocannabinol (THC). The prolonged depressor but not the pressor response was reduced after alpha-adrenergic receptor blockade or cervical spinal cord transection and was inhibited by the cannabinoid type 1 (CB1) receptor antagonist SR141716A, suggesting CB1 receptor-mediated sympathoinhibition as the underlying mechanism. Here we examined the relationship between sympathetic tone and the cardiovascular effects of anandamide by testing these effects in both conscious and anesthetized, normotensive and spontaneously hypertensive rats. In urethane-anesthetized normotensive rats, SR141716A inhibited the prolonged depressor and bradycardic effects of anandamide and THC with similar potency, whereas it did not affect the pressor response to either agent. Anadamide caused similar hypotension in spontaneously breathing and in paralyzed, mechanically ventilated rats, suggesting that the hypotension is not secondary to respiratory effects. In conscious normotensive rats, anandamide elicited transient vagal activation and a brief pressor response, but the prolonged hypotensive component was absent. SR141716A potentiated and prolonged the brief pressor response to anandamide, suggesting that the depressor response may have been masked by an increased pressor response. All three phases of the anadamide response were present in both anesthetized and conscious spontaneously hypertensive rats, and the hypotensive component, inhibited by SR141716A in both, was more prolonged in the absence (> 50 minutes) than the presence (10 to 15 minutes) of anesthesia. We conclude that anandamide causes a non-CB1 receptor-mediated pressor and a CB1 receptor-mediated prolonged depressor response. The depressor response can be elicited in both conscious and anesthetized animals, but its magnitude depends on preexisting sympathetic tone.

Mechanism of the hypotensive action of anandamide in anesthetized rats

We studied the effects of the endogenous cannabinoid ligand anandamide on blood pressure, single unit activity of barosensitive neurons in the rostral ventrolateral medulla, and postganglionic splanchnic sympathetic nerve discharge in urethane-anesthetized rats. In rats with an intact baroreflex, an intravenous bolus of 4 mg/kg anandamide caused a triphasic blood pressure response: transient hypotension, followed by a brief pressor and more prolonged depressor phase. Anandamide evoked a "primary" increase in neuronal firing coincident with its pressor effect and a "secondary," baroreflex-mediated rise coincident with its depressor effect at both sites. Pretreatment of rats with phentolamine or trimethaphan did not inhibit either the pressor response or the primary increase in splanchnic nerve discharge elicited by anandamide. In barodenervated rats, electrical stimulation of the rostral ventrolateral medulla increased blood pressure and splanchnic nerve discharge. Anandamide treatment blunted the rise in blood pressure without affecting the increase in splanchnic nerve discharge. Anandamide did not affect the rise in blood pressure in response to an intravenous bolus dose of phenylephrine. The results indicate that (1) the brief pressor response to anandamide is not sympathetically mediated, and (2) the prolonged hypotensive response to anandamide is not initiated in the central nervous system, in ganglia, or at postsynaptic adrenergic receptors but is due to a presynaptic action that inhibits norepinephrine release from sympathetic nerve terminals in the heart and vasculature.

Treatment of hyperlipidemia after heart transplantation and rationale for the Heart Transplant Lipid Registry

Hyperlipidemia occurs frequently after heart transplantation, and accelerated coronary artery disease remains the major cause of morbidity and mortality in patients who survive more than 1 year after heart transplantation. However, the risks and benefits of lipid-lowering therapy after heart transplantation remain poorly defined, and national guidelines for lipid-lowering drug therapy do not specifically address treatment of dyslipidemia in transplant recipients. Since the initial reports in the 1980s of rhabdomyolysis in heart transplant patients receiving high-dosage lovastatin, results of 11 post-transplantation series that used lovastatin, simvastatin, or pravastatin at lower dosages as drug monotherapy have been published. These studies have shown an overall 1% incidence of rhabdomyolysis, defined as creatine kinase > 10 times the upper limit of normal plus muscle symptoms. One randomized, controlled prospective trial has investigated the effects of lipid-lowering pharmacotherapy on patient outcome in cardiac transplant recipients. At 1-year follow-up in this nonblinded, single-center trial, patients treated with pravastatin (20 or 40 mg/day) initiated within 2 weeks of transplantation had a significant reduction in mortality rate and a significantly lower incidence of transplant arteriopathy. A number of important issues remain unanswered regarding treatment guidelines in patients with hyperlipidemia after heart transplantation. In January 1995 we began the Heart Transplant Lipid Registry, with 12 participant centers, to gather data prospectively on the efficacy and safety of lipid-lowering drugs in the treatment of dyslipidemia after heart transplantation.

Azathioprine and allopurinol: the price of an avoidable drug interaction

OBJECTIVE

To report the price of a drug interaction between azathioprine and allopurinol that resulted in pancytopenia in a patient who had undergone a heart transplant.

CASE SUMMARY

A 63-year-old white man who received an orthotopic heart transplant in 1987 was hospitalized in June 1991 with a diagnosis of pancytopenia. His immunosuppressive medications on admission included cyclosporine 125 mg bid, azathioprine (AZA) 200 mg/d, and prednisone 2.5 mg/5 mg every other day. Six weeks prior to admission, the patient's local physician prescribed allopurinol for left wrist pain suspected to be gout. It was determined that the pancytopenia was caused by the drug interaction between AZA and allopurinol, both of which were withheld on admission. During hospitalization, the patient's white blood cell count dropped to 1.1 x 10(3)/mm3 with an absolute neutrophil count of less than 0.5 x 10(3)/mm3, a platelet count of less than 20 x 10(3)/mm3, and a hemoglobin of 3.7 g/dL. Four units of packed red blood cells were transfused and regramostim (GM-CSF) therapy was begun on hospital day 3 to speed the marrow recovery process. The patient was discharged on hospital day 8 and AZA, which had been withheld since admission, was restarted. The dosage was titrated to 200 mg/d over the following 2 weeks. The price of this patient's hospital stay was $13,042.

DISCUSSION

Not included in this price was the effect this drug interaction had on the patient's quality of life. Even after discharge from the hospital, it was estimated that it would take up to 3 months for the patient to fully recover his previous level of strength and functional capability. This interaction between AZA and allopurinol could easily have been avoided. Both the physician and the pharmacist missed this well-documented and potentially life-threatening drug interaction. Also, the patient failed to notify the transplant team when allopurinol was prescribed by his local physician. The importance of patient responsibility for medication therapy must be stressed to help avoid unnecessary drug interactions.

CONCLUSIONS

Undetected drug interactions can be life-threatening to patients as well as costly to the healthcare system. Drug interactions also can have a profound negative effect on the patients' quality of life, the price of which cannot be measured in dollars alone. It is vital that the physician, pharmacist, and patient work together to optimize therapeutic outcomes and avoid unnecessary drug interactions.

Considerations for using ketoconazole in solid organ transplant recipients receiving cyclosporine immunosuppression

Drug interactions involving cyclosporine following transplantation are a challenging issue for the transplant clinician. This is especially true when ketoconazole is the second agent used in conjunction with cyclosporine. Because both agents are metabolized by the cytochrome P-450 IIIA4 enzyme system, cyclosporine levels rise dramatically in the presence of ketoconazole. Many other agents interact with ketoconazole, either by competitive enzyme inhibition in the liver and gastrointestinal tract, or by reducing the absorption of ketoconazole by agents that increase the pH of the gastrointestinal tract. Despite the potential cost savings when using ketoconazole to reduce cyclosporine doses, adverse effects associated with ketoconazole put patients at risk when using this combination. Close monitoring of cyclosporine levels is imperative when adding ketoconazole to cyclosporine, and once the dosage adjustments are complete, the addition of a third drug that interacts with either cyclosporine or ketoconazole could result in an unexpected rejection episode or toxic cyclosporine side effect.

Inhibition of exocytotic noradrenaline release by presynaptic cannabinoid CB1 receptors on peripheral sympathetic nerves

1. Activation of CB1 receptors by plant cannabinoids or the endogenous ligand, anandamide, causes hypotension via a sympathoinhibitory action in anaesthetized rats. In mouse isolated vas deferens, activation of CB1 receptors inhibits the electrically evoked twitch response. To determine if these effects are related to presynaptic inhibition of noradrenaline (NA) release, we examined the effects of delta 9-tetrahydrocannabinol (delta 9-THC), anandamide and the CB1 antagonist, SR141716A, on exocytotic NA release in rat isolated atria and vasa deferentia. 2. In isolated atria and vasa deferentia preloaded with [3H]-NA, electrical field stimulation caused [3H]-NA release, which was abolished by tetrodotoxin 0.5 microM and concentration-dependently inhibited by delta 9-THC or anandamide, 0.3-10 microM. The inhibitory effect of delta 9-THC and anandamide was competitively antagonized by SR 141716A, 1-10 microM. 3. Tyramine, 1 microM, also induced [3H]-NA release, which was unaffected by tetrodotoxin, delta 9-THC or anandamide in either atria or vasa deferentia. 4. CB1 receptor mRNA is present in the superior cervical ganglion, as well as in whole brain, cerebellum, hypothalamus, spleen, and vas deferens and absent in medulla oblongata and atria, as demonstrated by reverse transcription-polymerase chain reaction. There was no evidence of the presence of CB1A receptor mRNA in ganglia, brain, or cerebellum. These results suggest that activation of presynaptic CB1 receptors located on peripheral sympathetic nerve terminals mediate sympathoinhibitory effects in vitro and in vivo.

Important interactions of drugs with immunosuppressive agents used in transplant recipients

Solid organ transplant recipients depend on multiple immunosuppressive drugs, given in combination, to prevent rejection of their allografts. These patients often require many other therapeutic agents to treat underlying illnesses or concurrent diseases. Whenever a new medication is administered to a transplant patient, the potential exists for increasing or decreasing the tissue concentrations of immunosuppressive agents. This can lead to serious complications, such as over-immunosuppression and infection, under-immunosuppression and acute rejection, or additive toxicities, including nephrotoxicity. New immunosuppressants are under development and in clinical use, such as FK506, deoxyspergualin, OG 37-325, rapamycin, brequinar, and mycophenolate mofetil, thereby creating the possibility of many new drug-drug interactions.

Chronic manipulation of dietary salt modulates renal physiology and kidney dopamine receptor subtypes: functional and autoradiographic studies

1. Compared to rats maintained on the normal NaCl (0.33%) diet, animals maintained on the low NaCl (0%) diet for 4 weeks exhibited increased plasma aldosterone and chloride and decreased urinary sodium excretion. 2. Rats maintained on the high NaCl (8%) diet for 4 weeks showed increased systolic blood pressure, water intake, urine volume, sodium and dopamine excretion and decreased plasma aldosterone and glomerular filtration rate. 3. Administration of SCH 23390 (10 mg/kg, po), but not domperidone to the high salt diet rats attenuated the diuretic effect, indicating the involvement of DA1 rather than DA2 receptors. The dopamine decarboxylase inhibitor, carbidopa (30 mg/kg, i.p.), also reduced the high salt-induced diuresis. 4. Kidney sections from rats fed the low NaCl diet showed a 63-100% decrease (P < 0.001-0.02) in cortical and medullary DA1 and DA2 binding sites, while rats fed the high NaCl diet demonstrated only a 70% decrease (P < 0.01-0.02) in cortical DA1 binding, without affecting DA2 binding. 5. These data indicate that chronic modification of dietary salt profoundly affects the sodium, water and dopamine excretion and leads to selective modulation of renal dopamine receptor subtypes.

Changes in health-related quality of life and depression in heart transplant recipients

BACKGROUND

The intent of this study was to measure health-related quality of life and depression in 94 heart transplant recipients.

METHODS

Changes in health-related quality of life and depression were examined by administering the Sickness Impact Profile and the Beck Depression Inventory before heart transplantation, as well as 4, 8, 12, 24, 36, 48, and 60 months after surgery.

RESULTS

Sickness Impact Profile scores obtained before heart transplantation highlighted the greatest health-related quality of life dysfunction in work, sleep and rest, home management, and recreation and pastimes. Posttransplantation measures suggested improvement (p < 0.05) in emotional behavior, home management, mobility, ambulation, depression, eating behavior, social interaction, body care and movement, sleep and rest, recreation and pastimes, depression, and physical, overall, and psychosocial functioning. Continued improvement was noted up to 5 years after transplantation although patients continued to have marked work-related dysfunction. Age, medication regimen, rejection episodes, and a variety of preoperative medical variables were not related to health-related quality of life. Actuarial survival rates at 1, 2, 3, 4, and 5 years were 89%, 87%, 80%, 79%, and 79%, respectively.

CONCLUSIONS

Our results suggest that as early as 4 months after heart transplantation, patients show excellent functioning in most health-related quality of life areas. Survival rates are encouraging. Patients did not generally experience problems with depression within the first 4 months after heart transplantation. Notable problems remain after transplantation in rate of return to work where only 53% returned to work by 5 years after heart transplantation.

The estimation of the plasma free fraction of cyclosporine in rabbits and heart transplant patients: the application of a physiological model of renal clearance

We estimated the free fraction (fu) of cyclosporine (CyA) in the plasma from concentrations of CyA in urine (Cu) and plasma (Cp), urine flow rate (UF), and glomerular filtration rate in rabbits and in heart transplant patients. Following intravenous administration of CyA (5-30 mg kg-1) in ten NZW rabbits and oral administration of CyA (4.8-12.1 mg kg-1) in nine heart transplant patients, CyA concentrations in urine and plasma were measured by HPLC. The ratios of Cu to Cp and UF data were fitted to a physiological model of renal clearance using NONMEM. The free fraction of cyclosporine in the rabbits and the heart transplant patients was 0.0122 and 0.14, respectively. Because of the relatively low permeability of CyA across the tubular epithelium, no apparent equilibrium between Cu and Cp at any urine flow rate was reached and, therefore, the Cu to Cp ratio will not be equal to fu.

Practices of cardiothoracic transplant centers regarding hepatitis C-seropositive candidates and donors

The purpose of this survey was to determine current practices of cardiothoracic transplant centers regarding transplantation of hearts and lungs into hepatitis C (HCV)-seropositive candidates and the use of organs from HCV-seropositive donors. A telephone survey of 48 cardiothoracic transplant centers was conducted in October 1992. Questions included the center's policy for listing HCV-seropositive candidates; if, and under what conditions, organs from HCV-seropositive donors would be used; and which HCV assays were used. Forty-five programs responded; 75% will list an HCV-seropositive candidate, either directly or by lack of routine screening to exclude such patients; only 16% will not accept HCV-seropositive candidates; 9% had no policy. Overall, 69% will accept organs from HCV-seropositive donors, at least for selected recipients (22% for any recipient, 45% for HCV-seropositive and/or status I recipients; 2% do not screen donors). A total of 27% will never accept organs from an HCV-seropositive donor, and 4% had no policy. Thirty centers provided information on HCV methodology. All but one use a second generation ELISA or EIA as a first-line test. A positive result will be followed by a confirmatory assay/liver biopsy in 42%. The variation in practices reflects the ambiguity in the literature. Adequate evaluation of morbidity and mortality due to HCV infection in this population has not yet been possible, although currently available reports do not show a substantial increase. Prospective controlled trials in cardiothoracic transplant patients are necessary.

Does ciprofloxacin interact with cyclosporine?

OBJECTIVE

To provide the reader with a review of the literature that evaluates whether a pharmacokinetic or pharmacodynamic drug interaction exists between ciprofloxacin and cyclosporine.

DATA SOURCES

A MEDLINE search was used to identify pertinent review articles, pharmacokinetic studies, and case reports.

STUDY SELECTION

As both pharmacokinetic trials and case reports were few in number, all available sources were reviewed.

DATA EXTRACTION

A few case reports were reviewed; however, data were extracted primarily from prospective human studies involving cyclosporine pharmacokinetic profiles.

DATA SYNTHESIS

Ciprofloxacin has been reported to interact with cyclosporine during concomitant use through an interaction with the cytochrome P-450 system or by additive nephrotoxicity. Because ciprofloxacin may be used to treat a variety of infections in transplant recipients who receive cyclosporine, it is important to determine whether an interaction exists. Although cyclosporine is known to cause nephrotoxicity, only a few reports of ciprofloxacin-induced acute renal failure exist, all involving an immune-mediated interstitial nephritis. Four case reports have suggested a possible pharmacokinetic or pharmacodynamic drug interaction between cyclosporine and ciprofloxacin; however, many pharmacokinetic studies have refuted these reports. Several studies performing cyclosporine pharmacokinetic profiles have documented no increased cyclosporine concentrations, thus supporting the premise that ciprofloxacin does not interact with cyclosporine.

CONCLUSIONS

Controlled studies involving cyclosporine pharmacokinetic profiles do not support a pharmacokinetic or pharmacodynamic drug interaction between ciprofloxacin and cyclosporine. Although anecdotal case reports have suggested synergistic nephrotoxicity, no clear correlation can be made. Based on our review of the literature, it can be concluded that cyclosporine and ciprofloxacin may be used together safely at the recommended dosages without increased cyclosporine monitoring.

The impact of steroid withdrawal on the development of lipid abnormalities and obesity in heart transplant recipients

Hyperlipidemia and obesity are common problems after heart transplantation, which may increase the risk of chronic graft atherosclerosis. The intent of this study was to (1) determine the impact of a history of hyperlipidemia on the occurrence of lipid abnormalities after transplantation, (2) compare lipid profiles of those patients being treated with triple-drug immunosuppression versus those patients weaned from prednisone therapy, and (3) identify any factors that would predict which patients are at highest risk for the development of hyperlipidemia after transplantation. Of 89 patients who lived for more than 12 months, 35 patients had a history of hyperlipidemia before heart transplantation (cholesterol level of more than 240 mg/dl; low-density lipoprotein cholesterol level of more than 160 mg/dl). The most dramatic rise in cholesterol level was observed in patients with no history of hyperlipidemia who were treated with triple-drug immunosuppression, in whom a 64% increase occurred versus a 24% increase in patients receiving steroid-free immunosuppression (p < 0.001). In patients with a history of hyperlipidemia, cholesterol level increased by 20% with triple-drug immunosuppression versus 14% with steroid-free immunosuppression (p = 0.613); however, 83% of the patients in the triple-drug group and 92% in the steroid-free group had elevated cholesterol levels. Multiple regression analysis revealed that significant independent and additive (p < 0.00001) contributions with respect to percent change in cholesterol level were evident for (1) a negative history of hyperlipidemia (p = 0.005), (2) triple-drug immunosuppression (p = 0.0021), and (3) female sex (p = 0.0113). A negative history of hyperlipidemia was predictive of the percent change in low-density lipoprotein cholesterol level (p = 0.0049), and triple-drug immunosuppression administration predicted the percent change in high-density lipoprotein cholesterol (p = 0.0119). Patients with a positive history of hyperlipidemia had higher lipid values at 12 and 24 months after transplantation; however, patients with no previous history of hyperlipidemia experienced the greatest percent change in both cholesterol and low-density lipoprotein levels. Patients receiving prednisone therapy gained more weight (9.0 +/- 7.0 kg) as compared with those patients tapered from prednisone therapy (5.9 +/- 8.6 kg); however, neither the increase in actual weight (p = 0.120) nor the increase in percent ideal body weight (14% +/- 11% versus 9% +/- 13%, respectively) were significant (p = 0.133). This study identified that postoperative weight gain is best predicted by premorbid habitus, rather than the type of immunosuppression used.(ABSTRACT TRUNCATED AT 400 WORDS)

The pharmacokinetics and pharmacodynamics of immunosuppressive agents

Designing immunosuppressive regimens for the pediatric transplant patient is challenging because one must balance the need to provide adequate immunosuppression without interfering with normal growth processes or causing long-term adverse consequences. To optimize immunosuppressive therapy and minimize toxicity, it is necessary for the nurse to be knowledgeable of the pharmacokinetic and pharmacodynamic characteristics of the various agents. It is also important to understand which drugs interact with immunosuppressive agents and how to manage these interactions.

Postmortem changes and pharmacokinetics: review of the literature and case report

OBJECTIVE

To review the mechanisms and sequence of events that occur during ischemia and cell death and following death of the human body. The impact of these postmortem events on the distribution and pharmacokinetic behavior of drugs is described. The case study presented illustrates a possible situation where such postmortem changes could have affected the pharmacokinetics of procainamide.

DATA SOURCES

English-language journal articles and reference texts identified from pertinent data sources.

DATA SYNTHESIS

Postmortem changes in the human body begin at the cellular level with the onset of ischemia. As the length of time of ischemia increases and death ensues, more changes occur and lead to deterioration in tissue and organ function. These changes may affect the pharmacokinetic and distribution behavior of certain drugs. Drugs particularly affected are those whose distribution is dependent on molecular size, lipophilicity, pH, energy-dependent transport, and tissue binding. Such drugs include the tricyclic antidepressants, digoxin, and cimetidine. Other drugs with similar characteristics, such as procainamide, may also demonstrate like changes in distribution and pharmacokinetics.

CONCLUSIONS

When measuring drug concentrations after death, it is important to consider the phenomenon of postmortem redistribution. Postmortem drug concentrations may not be a true reflection of antemortem concentrations and as a result, wrong conclusions could be made about the cause of death. More studies characterizing the postmortem distribution and pharmacokinetic characteristics of specific drugs are necessary.

Steroid-free maintenance immunotherapy: Minneapolis Heart Institute experience

Recent advances in immunotherapy have resulted in improved survival after heart transplantation. The use of OKT3 as an induction agent has allowed the identification of a subset of patients who can be successfully withdrawn from prednisone and maintained on only cyclosporine and azathioprine. The latter regimen offers several theoretic advantages in terms of freedom from complications of long-term steroid therapy. To compare both the long-term efficacy and toxicity of steroid-free maintenance immunosuppression with triple-drug therapy, the medical records of 68 patients undergoing transplantation at the Minneapolis Heart Institute during a 3-year period (1988 through 1990) were reviewed. Thirty-six patients were treated with OKT3 induction immunotherapy, 29 were successfully tapered off prednisone by 114 +/- 44 days after transplantation, whereas 32 patients were maintained on triple-drug therapy. The incidence of treated rejection was equivalent in both groups; however, the time to first rejection was longer in patients treated with OKT3/steroid-free maintenance (205 +/- 214 vs 27 +/- 17 days) (p = 0.02). Bacterial infections during the early posttransplant period were more common in the OKT3/steroid-free maintenance group (p = 0.008); however, fungal and viral infections were equally distributed between both groups. The incidence of hypertension was slightly higher in patients maintained on prednisone (67% vs 51%; p = 0.242).(ABSTRACT TRUNCATED AT 250 WORDS)

OKT3 induction and steroid-free maintenance immunosuppression for treatment of high-risk heart transplant recipients

A group of high-risk heart transplant patients (n = 35) were treated from May 1987 through June 1990, with murine-derived monoclonal CD3 antibody (OKT3) induction therapy and steroid-free maintenance immunosuppression. This group was compared with a group of transplant patients (n = 47) who were not considered high risk and who were treated simultaneously with triple-drug immunosuppression (cyclosporine, azathioprine, and prednisone). The 1- and 3-year actuarial survival rates were similar: 97% and 91% for the OKT3 and 92% and 85% for the triple-drug immunosuppression groups, respectively. The overall incidence of rejection was equal for both groups (56%). No rejection occurred during the OKT3 course and rejection episodes occurred significantly later in patients treated with OKT3, with a mean first rejection episode of 111 +/- 104 days versus 27 +/- 21 days for the triple-drug immunosuppression group (p less than or equal to 0.05). Bacterial infections were seen more frequently (29% vs 6% of the patients treated) in the early period (less than 3 months) in the OKT3 group (p = 0.01) and were associated with the use of mechanical assistance in this group. The incidence of late infections or cytomegalovirus disease was similar for both groups. Patients treated with OKT3 and subsequent steroid-free maintenance immunosuppression had no significant posttransplantation increases of serum cholesterol levels, and hypertension was less common. Initial hospitalization was longer (p less than or equal to 0.05) in the OKT3 group (23 +/- 19 vs 13 +/- 5 days) but after the initial discharge the number of hospital days for the first year was similar for both groups (8 +/- 14 vs 9 +/- 13 days). Ventricular function at 1 year after transplantation was similar for both groups with average ejection fraction of 57% and 59% for the OKT3 and triple-drug immunosuppression groups, respectively. In conclusion, high-risk patients treated with OKT3 and steroid-free maintenance immunosuppression were managed on smaller doses of immunosuppressive drugs in the early postoperative period, and had excellent long-term survival rates. In this group of patients, rejection was delayed and the incidence of hypercholesterolemia, hypertension, and steroid-induced complications was decreased. Such a regimen offers a relatively drug-free period in the early posttransplant stages and freedom from the long-term complications of steroids.

Mechanical circulatory assistance after heart transplantation

From October 1985 through December 1989, 92 heart transplant procedures were performed in 89 patients. Nine patients (aged 19 to 66 years; 7 male, 2 female) required mechanical circulatory support after transplantation because of primary idiopathic organ failure (n = 2), implant difficulty (2), poor organ quality (2), or acute right heart failure (3). Devices used included the intraaortic balloon pump (6), centrifugal right ventricular assist device (2), left ventricular assist (1), biventricular assists (2), and total artificial heart (1). Two patients required multiple devices. One patient underwent retransplantation. Implant time ranged from 1 to 18 days. One early death occurred owing to right heart failure 6 days after transplantation, 7 hours after removal of a right ventricular assist device, for an overall mortality of 11%. The remaining 8 patients are alive 4 months to 28 months after transplantation. The actuarial 1-year survival of 89% +/- 10% compares well with the survival of 87% +/- 4% for the entire transplant group. All surviving patients are in functional class I. Echocardiographic examination in all patients revealed left ventricular ejection fraction to be normal in 7 and depressed in 1. Extending the criteria for organ donors or difficulty with the implant procedure can lead to early organ failure, which may be reversible with circulatory assistance allowing excellent survival.

Ganciclovir pharmacokinetics during renal impairment

Limited information is available concerning the use of ganciclovir (GCV) in patients with severe renal impairment. The pharmacokinetics of GCV were studied in a heart transplant recipient requiring hemodialysis. The total body clearance was calculated to be approximately 5% of that previously reported for patients with normal renal function. GCV was removed by hemodialysis; a single 4-h procedure decreased the concentration in plasma by approximately 50%. GCV can be safely administered to patients with renal insufficiency if concentrations in plasma are monitored.

Evaluation of a method for initiating vancomycin therapy: experience in 205 patients

This study evaluated a dosing method for initiating vancomycin therapy in a large population based on patients' age, weight, and renal function. The aims were to determine the method's efficacy in achieving predetermined peak and trough serum concentrations, and to calculate the cost savings incurred by individualizing therapy. Average doses +/- 1 SD of 7.93 +/- 0.29 mg/kg corrected body weight (lean body weight + 40% excess weight) were administered at intervals predicted by the patients' estimated creatinine clearances (range 22-130 ml/min). The calculated mean dose +/- SD was 558 +/- 83 mg (range 350-750 mg) and the calculated median interval was 12 hours (range 6-24 hr). Peak and trough concentrations +/- SD measured at steady state averaged 26.0 +/- 5.4 and 7.3 +/- 2.3 micrograms/ml, respectively. Peak and trough serum concentrations fell within the predetermined therapeutic range in 311 (76%) of 410 samples. Peak concentrations were in the range of 20-30 micrograms/ml in 145 (71%) of 205 samples. Trough concentrations were in the range of 5-10 micrograms/ml in 166 (81%) of the 205 samples. This simplified dosing method successfully individualized therapy in most patients, and produced a significant savings to the pharmacy in reduced drug acquisition costs and to patients in reduced drug charges.

Antibiotic prophylaxis in open-heart surgery patients: comparison of cefamandole and cefuroxime

The efficacy of cefamandole and cefuroxime in preventing postoperative wound infections was compared in 3037 patients undergoing open-heart surgery. Antibiotic prophylaxis in 1467 patients having coronary artery bypass and valve replacement surgery was cefamandole 2 g iv preoperatively followed by 2 g q6h for five days postoperatively; 1570 patients received cefuroxime 1.5 g iv preoperatively then 1.5 g iv q 12h for three days postoperatively. Postoperative wound infections (sternal and leg wounds) were studied in each treatment group. In the cefamandole study group, 27 patients (1.8 percent) developed postoperative wound infections (9 sternal and 18 leg wounds). In the cefuroxime treatment group, 19 patients (1.2 percent) developed postoperative wound infections (9 sternal and 10 leg wounds). Overall, no statistical difference was found between the two antibiotics in preventing postoperative wound infections. However, in patients having valve replacement surgery, cefuroxime was found statistically more effective than cefamandole prophylaxis in preventing sternal wound infections (no infections in 284 patients compared with five infections in 205 patients, respectively, p = 0.01). The most common organism isolated from infected wounds with cefamandole was Staphylococcus aureus followed by S. epidermidis compared with cefuroxime which had S. epidermidis followed by S. aureus. Cefuroxime was found to be as effective as cefamandole and considerably less expensive in preventing postoperative wound infections in patients undergoing open-heart surgery.