Drug elimination in chronic liver diseases

An overview of acute gastrointestinal side effects of systemic anti-cancer therapy and their management

Treatment-related acute gastrointestinal toxicities are a common and often debilitating hurdle encountered in the treatment of cancer patients. While the introduction of targeted therapies such as tyrosine kinase inhibitors has led to improvements in survival outcomes, their use has also been complicated by a high frequency of clinically important adverse effects. Gastrointestinal toxicities such as nausea, vomiting, diarrhoea and hepatotoxicity represent potentially serious adverse events that may necessitate dose reductions, treatment interruptions and cessation of treatment. An improved knowledge of the incidence, pathophysiology, management and prophylaxis of these toxicities is crucial in order to reduce patient morbidity and mortality. In this review, we discuss the main gastrointestinal toxicities associated with chemotherapy and targeted therapies in oncology, outlining their incidence, pathophysiology and expert management guidelines.

Scintigraphic liver function and transient elastography in the assessment of patients with resectable hepatocellular carcinoma

BACKGROUND

Hepatobiliary scintigraphy (HBS) is used to quantify total and regional liver function. Transient elastography (TE) provides a non-invasive alternative to percutaneous biopsy to assess liver fibrosis and cirrhosis. This study aims to determine the correlation between HBS and histopathology of liver parenchyma, and to compare these with TE in patients with resectable hepatocellular carcinoma (HCC).

METHODS

Patients who underwent surgery for HCC between 2000 and 2016 after preoperative HBS were included. Non-tumorous liver tissue was evaluated for inflammation, steatosis, ballooning, siderosis and fibrosis. Correlation analysis was performed between HBS results and histopathological scoring. These were also compared with TE and surgical outcomes.

RESULTS

71 patients underwent preoperative HBS of whom 24 also had TE. HBS correlated with portal and lobular inflammation as well as fibrosis. TE correlated with portal and lobular inflammation, ballooning and fibrosis. A significant correlation was found between HBS and TE. No association was found with overall postoperative morbidity and mortality.

CONCLUSION

HBS and TE show a moderate to strong correlation. HBS and TE share discriminatory features of histopathological scoring and show a weak to moderate correlation with hepatic inflammation and fibrosis.

Gd-EOB-DTPA-enhanced T1 relaxometry for assessment of liver function determined by real-time 13C-methacetin breath test

OBJECTIVES

To determine whether liver function as determined by intravenous administration of ¹³C-methacetin and continuous real-time breath analysis can be estimated quantitatively from gadoxetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) relaxometry.

METHODS

Sixty-six patients underwent a ¹³C-methacetin breath test (¹³C-MBT) for evaluation of liver function and Gd-EOB-DTPA-enhanced T1-relaxometry at 3 T. A transverse 3D VIBE sequence with an inline T1 calculation based on variable flip angles was acquired prior to (T1 pre) and 20 min post-Gd-EOB-DTPA (T1 post) administration. The reduction rate of T1 relaxation time (rrT1) and T1 relaxation velocity index (∆R1) between pre- and post-contrast images was evaluated. ¹³C-MBT values were correlated with T1_post, ∆R1 and rrT1, providing an MRI-based estimated ¹³C-MBT value. The interobserver reliability was assessed by determining the intraclass correlation coefficient (ICC).

RESULTS

Stratified by three different categories of ¹³C-MBT readouts, there was a constant increase of T1 post with increasing progression of diminished liver function (p ≤ 0.030) and a constant significant decrease of ∆R1 (p ≤ 0.025) and rrT1 (p < 0.018) with progression of liver damage as assessed by ¹³C-methacetin breath analysis. ICC for all T1 relaxation values and indices was excellent (> 0.88). A simple regression model showed a log-linear correlation of ¹³C-MBT values with T1_post (r = 0.57; p < 0.001), ∆R1 (r = 0.59; p < 0.001) and rrT1 (r = 0.70; p < 0.001).

CONCLUSION

Liver function as determined using real-time ¹³C-methacetin breath analysis can be estimated quantitatively from Gd-EOB-DTPA-enhanced MR relaxometry.

KEY POINTS

• Gd-EOB-DTPA-enhanced T1 relaxometry quantifies liver function • Gd-EOB-DTPA-enhanced MR relaxometry may provide parameters for assessing liver function before surgery • Gd-EOB-DTPA-enhanced MR relaxometry may be useful for monitoring liver disease progression • Gd-EOB-DTPA-enhanced MR relaxometry has the potential to become a novel liver function index.

Medication prescribing in liver dysfunction

Patients with mental illness often have co-occurring substance abuse which increases the risk for developing cirrhosis, particularly with common etiologies such as hepatitis and alcoholic liver disease. As such, knowledge of how the disease may impact medication prescribing is important. Unfortunately, there is a paucity of data to guide medication prescribing in these patients. Product labeling information should be used in the clinical decision making process. Additionally, clinicians should consider the etiology of disease, adverse effect profile, and pharmacokinetic parameters including solubility, product formulation, protein binding, hydrophilicity, metabolism, bioavailability, extraction ratios, excretion route, and half-life. Thoughtful consideration should be given when prescribing potentially hepatotoxic medications, and those which may increase bleeding risk in patients with coagulopathy. It is essential to ensure every medication has an appropriate indication and carefully evaluate the need for each medication. Overall, more research is necessary to support clinical decision-making with outcomes based research in patients with chronic liver disease.

An evaluation of hepatotoxicity in breast cancer patients receiving injection Doxorubicin

BACKGROUND

Hepatic dysfunction in the cancer unit has a significant impact on patient outcomes. The therapeutic application of anthracycline antibiotics are limited by side-effects mainly myelosuppression, chronic cardiotoxicity, and hepatotoxicity.

AIM

To assess the risk of Hepatotoxicity in breast cancer patients receiving Inj. Doxorubicin.

SUBJECTS AND METHODS

The investigation was a prospective study that was conducted in cancer patients receiving Inj. Doxorubicin doses of 50 mg/m(2), and 75 mg/m(2) at a South Indian tertiary care hospital. Sample collection was carried out from pre-chemotherapy to 4(th) cycle. Serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), direct bilirubin and total bilirubin were assessed to determine hepatotoxicity. Data were analyzed using unpaired t-test, Pearson correlation using Graph-Pad Prism version 5.00 for Windows, Graph-Pad Software, San Diego, California, USA, www.graphpad.com.

RESULTS

Breast cancer patients comprised 37% (49/132) of the total female cancer patient population, of which 46 patients with a mean age of 46.6 (13.4) years were included and 30.4% (14/46) patients were developed hepatotoxicity. The mean standard deviation of SGOT, SGPT, direct bilirubin, total bilirubin in the pre-chemotherapy cycle to fourth chemotherapy cycle were found to be 21.97 (5.798) U/L and 181.3 (103.6) U/L, 23.17 (6.237) U/L and 147.6 (90.9) U/L, 0.1351 (0.1186) mg/dL and 0.5445 (0.4587) mg/dL, 0.3094 (1.346) mg/dL and 2.7163 (1.898) mg/dL simultaneously where P < 0.05 which were statistically significant.

CONCLUSION

There exist a strong correlation between the use of Inj. Doxorubicin and risk for developing hepatotoxicity. The health-care professionals dealing with breast cancer patients need to have awareness for hepatotoxicity with the use of Inj. Doxorubicin therapy.

Lack of effect of moderate hepatic impairment on the pharmacokinetics of oral oseltamivir and its metabolite oseltamivir carboxylate

AIMS

To compare the pharmacokinetics of oseltamivir and oseltamivir carboxylate in hepatically impaired patients and healthy subjects.

METHODS

Hepatically impaired patients (n = 11) and healthy subjects (n = 11) were individually paired on the basis of gender, age (+/-10 years) and body weight (+/-20%) and administered a single dose of oseltamivir (75 mg).

RESULTS

Oseltamivir and oseltamivir carboxylate C(max) were < or =6% and < or =19% lower, and their AUC(0,infinity) 33% higher and < or =19% lower, respectively, in hepatically impaired patients compared with healthy subjects. These changes are within the safety limits for the drug.

CONCLUSIONS

The metabolism of oseltamivir is not compromised [corrected] in hepatically impaired patients. No dose adjustment is required in these patients when receiving oseltamivir.

Hepatotoxicity of chemotherapy

After assessment of tumor histology, the next important factor to consider in the selection of a chemotherapy regime is organ function. Patients who are to receive chemotherapy require careful assessment of liver function prior to treatment to determine which drugs may not be appropriate, and which drug doses should be modified. Following therapy abnormalities of liver function tests may be due to the therapy rather than to progressive disease, and this distinction is of critical importance. Furthermore, not all abnormalities in liver function are due to the tumor or its treatment, and other processes, such as hepatitis, must be kept in mind. This article reviews the hepatic toxicity of chemotherapeutic agents, and suggests dose modifications based upon liver function abnormalities. Emphasis is placed on agents known to be hepatotoxic, and those agents with hepatic metabolism.

Clinical importance of non-genetic and genetic cytochrome P450 function tests in liver disease

Liver disease is associated with reduced metabolic capacity for drugs that are metabolized by oxidative biotransformation. Three cytochrome P450 (P450 or CYP) gene families in liver microsomes (CYP 1, CYP2 and CYP3) appear to be responsible for much of the drug metabolism that takes place. The genetic polymorphism of the CYPs responsible for debrisoquine/ sparteine (CYP2D6) metabolism and S-mephenytoin (CYP2C19) metabolism has been well documented, but information on the impairment of each isoform in liver disease is still limited. There are two types of hepatic P450 function tests. One type consists of non-genetic P450 function tests (CYP1A2, 2A6, 2C9/10, 2E1 and 3A3/4), and probe drugs include caffeine, catalysed by CYP1A2, coumarin by CYP2A6, phenytoin by CYP2C6, chlorzoxazone by CYP2E1, and nifedipine, erythromycin and lidocaine by CYP3A3/4. The second type of genetic P450 function tests (CYP2C19 and CYP2D6) involves probe drugs such as S-mephenytoin, catalysed by CYP2C19, and debrisoquine and sparteine, catalysed by CYP2D6. The metabolism of the probe drugs used in non-genetic P450 function tests in patients with liver disease falls into two categories: reduced (CYP1A2, CYP2C, 2E1 and 3A) and unchanged (CYP2C). In genetic P450 function tests there seems to be a lesser degree of inhibition in poor metabolizers (PMs) than extensive metabolizers (EMs) among patients with liver disease. There have been very few reports on changes in metabolism of the probe drugs used in genetic P450 function tests in liver disease. In this paper the subject is reviewed.

Prediction by mathematical simulation of different pathophysiological effects on D-sorbitol bioavailability

In this study a mathematical model was applied to predict how changes in hepatic extraction ratio (E), fractional portal inflow (P) and renal elimination ratio (R) may affect fractional D-sorbitol bioavailability in cirrhotic patients. D-sorbitol bioavailability was computed as the ratio between cumulative urinary outputs measured after infusion into the superior mesenteric (Uma) or the hepatic artery (Uha) and a systemic vein (Usv). The present work was aimed at explaining by mathematical simulation the very large difference observed in the regression lines when plotting Uma or Uha against Usv values. The study was performed by considering a pathophysiological model of the hepatic circulation and simulating independent variations of the above considered parameters or assuming particular pathophysiological conditions like hepatic arterialization and hepatofugal flow. Computational results account for the wide dispersion of experimental data obtained in previous studies and provide reasonable explanations of unexpected findings.