Antipyrine clearance in chronic and neoplastic liver diseases: a study of 518 patients

Influence of Inflammation on Cytochromes P450 Activity in Adults: A Systematic Review of the Literature

Background: Available in-vitro and animal studies indicate that inflammation impacts cytochromes P450 (CYP) activity via multiple and complex transcriptional and post-transcriptional mechanisms, depending on the specific CYP isoforms and the nature of inflammation mediators. It is essential to review the current published data on the impact of inflammation on CYP activities in adults to support drug individualization based on comorbidities and diseases in clinical practice. Methods: This systematic review was conducted in PubMed through 7th January 2021 looking for articles that investigated the consequences of inflammation on CYP activities in adults. Information on the source of inflammation, victim drugs (and CYPs involved), effect of disease-drug interaction, number of subjects, and study design were extracted. Results: The search strategy identified 218 studies and case reports that met our inclusion criteria. These articles were divided into fourteen different sources of inflammation (such as infection, autoimmune diseases, cancer, therapies with immunomodulator…). The impact of inflammation on CYP activities appeared to be isoform-specific and dependent on the nature and severity of the underlying disease causing the inflammation. Some of these drug-disease interactions had a significant influence on drug pharmacokinetic parameters and on clinical management. For example, clozapine levels doubled with signs of toxicity during infections and the concentration ratio between clopidogrel's active metabolite and clopidogrel is 48-fold lower in critically ill patients. Infection and CYP3A were the most cited perpetrator of inflammation and the most studied CYP, respectively. Moreover, some data suggest that resolution of inflammation results in a return to baseline CYP activities. Conclusion: Convincing evidence shows that inflammation is a major factor to be taken into account in drug development and in clinical practice to avoid any efficacy or safety issues because inflammation modulates CYP activities and thus drug pharmacokinetics. The impact is different depending on the CYP isoform and the inflammatory disease considered. Moreover, resolution of inflammation appears to result in a normalization of CYP activity. However, some results are still equivocal and further investigations are thus needed.

[Surgical risk in patients with liver disease]

The author draws attention on the importance surgical risk analysis from patient's safety point of view. Recently the development in quality assurance affected surgical practice as well, hence determination and evaluation of surgical risk are more exactly defined. This resulted in a significant decrease in mortality during surgical interventions on the liver despite a wider indication and increased numbers, recently. Importantly, surgical risk is much higher in patients with liver disease compared to patients with normal liver. The risk of surgical interventions for liver diseases (HCC, tumor) in patients with diffuse liver diseases (cirrhosis, chronic hepatitis, ALD) can be expressed numerically. For many years the Child-Turcotte-Pugh stadium could have been determined by using actual laboratory values. Recently the "50-50 rule" or more frequently the MELD score -- originally used in the practice of liver transplantation -- mean objective expression of surgical risk. Treatment optimalisation can reduce surgical risk, selected on the basis of risk analysis in multidisciplinary settings, which focus on the need of liver surgeons.

Mild hepatitis at recommended doses of acetaminophen in patients with evidence of constitutionally enhanced cytochrome P450 system activity

Acetaminophen (paracetamol) is used throughout the world for pain relief and antipyresis in both children and adults. In many countries, it can be purchased without a medical prescription and it is also a common component of a number of over-the-counter remedies for colds, influenza and the like. Fasting, malnutrition and use of alcohol and/or other drugs are thought to play causal roles in hepatotoxicity associated with recommended doses of acetaminophen although liver injury provoked by therapeutic doses has also been observed in the absence of these factors. We describe two patients who experienced subclinical hepatotoxic reactions after taking acetaminophen at therapeutic doses. The results of an antipyrine metabolism test suggest the presence of constitutional hyperactivity of the cytochrome P450-dependent mixed function oxidative system in both patients. We hypothesize that the latter contributed to the hepatotoxicity and that it may play a role in idiosyncratic reactions to this drug.

Comparison of MEGX (monoethylglycinexylidide) and antipyrine tests in patients with liver cirrhosis

The aim of the study was to compare the feasibility of the MEGX (monoethylglycinexylidide) and antipyrine tests in reference to standard biochemical parameters used for liver assessment in cirrhotic patients. The study was carried out in 44 subjects: 14 healthy controls and 30 cirrhotic patients classified according to the Child-Pugh's score to subgroups A (n=11), B (n=12) and C (n=7). All subjects underwent two dynamic liver tests, i.e. MEGX (monoethylglycinexylidide) and antipyrine test in a crossover schedule with at least 5-day interval. For the MEGX, lidocaine was administrated intravenously, at a dose of 1 mg/kg, and blood samples for MEGX assay were collected after 15 minutes. MEGX concentrations were measured by fluorescence polarization immunoassay. The antipyrine concentrations were evaluated following a single oral administration of 1000 mg antipyrine. The blood was sampled for 24 hours after the drug administration, and antipyrine concentrations were measured spectrophotometrically. Standard biochemical parameters used for liver assessment were measured by means of routine laboratory methods. It was concluded that in patients liver with cirrhosis, liver dynamic tests were better predictors of hepatic function. The MEGX test was more feasible in clinical setting, but it was noted that antipyrine test was more sensitive in staging liver cirrhosis.

Impairment of metabolic function in chronic hepatitis C is related to factors associated with resistance to therapy

OBJECTIVE

Liver disease causes a loss of hepatic function, and remission is associated with improved functional hepatic mass. The object of the present study was to investigate whether liver metabolic function assessed by antipyrine clearance is related to other disease characteristics influencing response to therapy in chronic hepatitis C.

METHODS

Patients (n = 96) received three different treatment regimens: one group received interferon alfa-2b for 48 wk; in a second group with maintained positive hepatitis C virus (HCV) RNA after 12 wk, interferon was combined for 36 wk with oral ribavirin; and patients who were relapsers or nonresponders to a previous therapy with interferon alone received interferon alfa-2b plus ribavirin for 48 wk.

RESULTS

Twenty-five patients (26%) showed sustained normalization of ALT levels and negative HCV RNA 6 months after therapy. The response was more likely to be sustained in patients with a genotype other than 1 (52.0% vs 15.5% in patients with genotype 1, p < 0.001), and the percentage of sustained responders was higher among patients who demonstrated negativity of HCV RNA at the end of 4 wk of treatment (64% vs 13% without negativity, p < 0.001). Sustained response was associated with significantly lower baseline serum ferritin (-46%, p < 0.01) and duration of infection (-33%, p < 0.01). Baseline antipyrine clearance was higher in sustained responders than in nonresponders (+19%, p < 0.05) and lower in genotype 1 patients than in those with a genotype other than 1 (-24%, p < 0.05). Antipyrine clearance increased by 12% at the end of the 48-wk course of treatment among sustained responders (+34% vs nonresponders, p < 0.001) and still remained elevated at the end of the follow-up (+35% vs nonresponders, p < 0.001).

CONCLUSION

In summary, the present study shows that liver oxidative metabolism is related to antiviral response rates and suggests that much of the effect is explained by viral genotype.