Malignancy, weight loss, and the small intestinal mucosa

Involvement of the Parathyroid Hormone-Related Protein on Changes in the CYP3A Expression in Cancer Cachexia

Parathyroid hormone-related protein (PTHrP), which is secreted from a tumor, contributes to the progression of cachexia, a condition that is observed in half of all cancer patients. Although drug clearance was reported to decrease in patients with cancer cachexia, the details have not been clarified. The present study reports on an investigation of whether PTHrP is involved in the alternation of drug metabolism in cases of cancer cachexia. Cancer cachexia model rats with elevated serum PTHrP levels showed a significant decrease in hepatic and intestinal CYP3A2 protein expression. When midazolam, a CYP3A substrate drug, was administered intravenously or orally to the cancer cachexia rats, its area under the curve (AUC) was increased by about 2 and 5 times, as compared to the control group. Accordingly, the bioavailability of midazolam was increased by about 3 times, thus enhancing its pharmacological effect. In vitro experiments using HepG2 cells and Caco-2 cells showed that the addition of serum from cancer cachexia rats or active PTHrP (1-34) to each cell resulted in a significant decrease in the expression of CYP3A4 mRNA. Treatment with a cell-permeable cAMP analog also resulted in a decreased CYP3A4 expression. Pretreatment with protein kinase A (PKA), protein kinase C (PKC), and nuclear factor-kappa B (NF-κB) inhibitors recovered the decrease in CYP3A4 expression that was induced by PTHrP (1-34). These results suggest that PTHrP suppresses CYP3A expression via the cAMP/PKA/PKC/NF-κB pathway. Therefore, it is likely that PTHrP would be involved in the changes in drug metabolism observed in cancer cachexia.

Impact of malnourishment on the pharmacokinetics of acetaminophen and susceptibility to acetaminophen hepatotoxicity

BACKGROUND

Acetaminophen hepatotoxicity is thought to be primarily caused by formation of the specific reactive metabolite N-acetyl-para-benzo-quinone imine (NAPQI). Malnourished individuals are at increased risk of acetaminophen-related hepatotoxicity. We report a case of low acetaminophen clearance in a severely underweight young woman, and elaborate on the possible effects of malnutrition on the total clearance of acetaminophen as well as on the separate contributions of the different metabolic pathways.

CASE REPORT

An 18-year-old Caucasian woman weighing 43 kg with a history of eating disorder-related hospital admissions presented at the emergency department after having ingested 33 tablets of acetaminophen 500 mg two hours earlier. She then received intravenous N-acetylcysteine for 33 h. Nine hours after ingestion, the acetaminophen elimination half-life (t½) was estimated to be >100 h.

DISCUSSION

While decreased total acetaminophen clearance (twofold) due to malnutrition has been reported in literature, the extremely low clearance in this specific patient cannot be explained. Malnourished individuals generally have reduced antioxidant reserves, coinciding with a shift in metabolic routes toward oxidative metabolism. This may result in increased formation of NAPQI and reduced neutralizing capacity, thereby increasing the risk of acetaminophen-induced hepatotoxicity. Evidence for this observation can be found in animal and to a lesser extent in human studies.

Impact of gastrointestinal tract variability on oral drug absorption and pharmacokinetics: An UNGAP review

The absorption of oral drugs is frequently plagued by significant variability with potentially serious therapeutic consequences. The source of variability can be traced back to interindividual variability in physiology, differences in special populations (age- and disease-dependent), drug and formulation properties, or food-drug interactions. Clinical evidence for the impact of some of these factors on drug pharmacokinetic variability is mounting: e.g. gastric pH and emptying time, small intestinal fluid properties, differences in pediatrics and the elderly, and surgical changes in gastrointestinal anatomy. However, the link of colonic factors variability (transit time, fluid composition, microbiome), sex differences (male vs. female) and gut-related diseases (chronic constipation, anorexia and cachexia) to drug absorption variability has not been firmly established yet. At the same time, a way to decrease oral drug pharmacokinetic variability is provided by the pharmaceutical industry: clinical evidence suggests that formulation approaches employed during drug development can decrease the variability in oral exposure. This review outlines the main drivers of oral drug exposure variability and potential approaches to overcome them, while highlighting existing knowledge gaps and guiding future studies in this area.

Pereira W, Maximiano LF, de Alcântara PS, Otoch JP, Trinchieri G, Laviano A, Muscaritoli M, Seelaender M. Cancer cachexia induces morphological and inflammatory changes in the intestinal mucosa

BACKGROUND

Cachexia is a multifactorial and multiorgan syndrome associated with cancer and other chronic diseases and characterized by severe involuntary body weight loss, disrupted metabolism, inflammation, anorexia, fatigue, and diminished quality of life. This syndrome affects around 50% of patients with colon cancer and is directly responsible for the death of at least 20% of all cancer patients. Systemic inflammation has been recently proposed to underline most of cachexia-related symptoms. Nevertheless, the exact mechanisms leading to the initiation of systemic inflammation have not yet been unveiled, as patients bearing the same tumour and disease stage may or may not present cachexia. We hypothesize a role for gut barrier disruption, which may elicit persistent immune activation in the host. To address this hypothesis, we analysed the healthy colon tissue, adjacent to the tumour.

METHODS

Blood and rectosigmoid colon samples (20 cm distal to tumour margin) obtained during surgery, from cachectic (CC = 25) or weight stable (WSC = 20) colon cancer patients, who signed the informed consent form, were submitted to morphological (light microscopy), immunological (immunohistochemistry and flow cytometry), and molecular (quantification of inflammatory factors by Luminex® xMAP) analyses.

RESULTS

There was no statistical difference in gender and age between groups. The content of plasma interleukin 6 (IL-6) and IL-8 was augmented in cachectic patients relative to those with stable weight (P = 0.047 and P = 0.009, respectively). The number of lymphocytic aggregates/field in the gut mucosa was higher in CC than in WSC (P = 0.019), in addition to those of the lamina propria (LP) eosinophils (P < 0.001) and fibroblasts (P < 0.001). The area occupied by goblet cells in the colon mucosa was decreased in CC (P = 0.016). The M1M2 macrophages percentage was increased in the colon of CC, in relation to WSC (P = 0.042). Protein expression of IL-7, IL-13, and transforming growth factor beta 3 in the colon was significantly increased in CC, compared with WSC (P = 0.02, P = 0.048, and P = 0.048, respectively), and a trend towards a higher content of granulocyte-colony stimulating factor in CC was also observed (P = 0.061). The results suggest an increased recruitment of immune cells to the colonic mucosa in CC, as compared with WSC, in a fashion that resembles repair response following injury, with higher tissue content of IL-13 and transforming growth factor beta 3.

CONCLUSIONS

The changes in the intestinal mucosa cellularity, along with modified cytokine expression in cachexia, indicate that gut barrier alterations are associated with the syndrome.

Gaps in predicting clinical doses for cannabinoids therapy: Overview of issues for pharmacokinetics and pharmacodynamics modelling

Model-based prediction on clinical doses for cannabinoids therapy is beneficial in the clinical setting, especially for seriously ill patients with both altered pharmacokinetics and pharmacodynamic responses. The objective of this article is to review the currently available PK and/or PD models of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) and to highlight the major issues for modelling this complex therapeutic area. A systematic search was conducted in the electronic databases PubMed and EMBASE using the key words 'cannabis', 'cannabinoid', 'tetrahydrocannabinol', 'THC', 'cannabidiol', 'CBD', 'pharmacokinetic model', 'pharmacodynamics model' and their combinations. Twelve empirical PK and/or PD models for THC for humans were identified. Among them, ten were developed from data of healthy participants and two were from ill patients. Models for CBD were not found. Model-based prediction on appropriate doses for cannabinoids therapy for ill patients is currently limited due to insufficiency of relevant PK and PD data. High-quality PK and PD data of cannabinoids for patients with different illnesses is needed for model development. Mechanism-based PK and PD models are promising for improved predictive dosing performance for ill and comorbid patients.

Influence of cancer cachexia on drug liver metabolism and renal elimination in rats

BACKGROUND

Body wasting and cachexia change body composition and organ function, with effects on drug pharmacokinetics. The aim of this study was to investigate how cancer and cancer cachexia modify liver metabolism and renal drug elimination in rats.

METHODS

Nine male Wistar-Han rats received a single oral dose of midazolam and propranolol (markers of hepatic metabolism), and 10 rats received single intravenous dose of iohexol, a marker of glomerular filtration rate. After drug delivery, multiple dried blood samples were obtained within 2 h post-dose to evaluate drug pharmacokinetic profiles. After baseline sampling (D0), rats were injected with tumour cells. Drug application and blood sampling were repeated when rats developed tumours (Day 5-D5), and when rats were severely cachectic (Day 10-D10). Clearance (CL) and volume of distribution (Vd) of drugs were assessed with non-linear mixed effects modelling. Weight and body composition were measured on D0 and D10 and were related to pharmacokinetic parameters.

RESULTS

All three drugs showed non-significant trend towards increased CL and Vd on D5. On D10, midazolam and propranolol CL and midazolam Vd significantly decreased from baseline (-80.5%, -79.8%, and -72.0%, respectively, P < 0.05 for all). Iohexol CL decreased by 29.8% from baseline value on D10, which was related to body weight loss (Pearson's r = 0.837, P = 0.019).

CONCLUSIONS

Hepatic metabolism and renal drug elimination are significantly reduced in cachexia, which could increase risk of dose-related adverse events.

Pharmacokinetics of drugs in cachectic patients: a systematic review

Cachexia is a weight-loss process caused by an underlying chronic disease such as cancer, chronic heart failure, chronic obstructive pulmonary disease, or rheumatoid arthritis. It leads to changes in body structure and function that may influence the pharmacokinetics of drugs. Changes in gut function and decreased subcutaneous tissue may influence the absorption of orally and transdermally applied drugs. Altered body composition and plasma protein concentration may affect drug distribution. Changes in the expression and function of metabolic enzymes could influence the metabolism of drugs, and their renal excretion could be affected by possible reduction in kidney function. Because no general guidelines exist for drug dose adjustments in cachectic patients, we conducted a systematic search to identify articles that investigated the pharmacokinetics of drugs in cachectic patients.

Factors related to and consequences of weight loss in patients with stomach cancer. The Norwegian Multicenter experience. Norwegian Stomach Cancer Trial

Of 1165 patients with stomach cancer included in a national, prospective multicenter study with 51 surgical units participating, information about weight loss before diagnosis was available for 855 patients (73%). Median weight loss was 5 kg; 259 patients (31%) experienced no weight loss. By logistic regression analysis the authors found that weight loss increased with age and advancing stages of disease (TNM Stage I-IV), with decreasing Karnofsky index, in Lauren's diffuse versus intestinal tumor type, and with tumors located at the cardia/esophagus. Increasing weight loss reduced the resectability rate significantly, but no association between weight loss and postoperative complication rate was found. The odds ratio for postoperative mortality was 2.5 to 1 for the weight loss group 5 to 10kg versus 0 kg. In conclusion, weight loss reflects a less favorable tumor status. Weight loss did not increase postoperative morbidity but did lead Weight to a higher death rate after surgery.

The effect of food on serum concentrations of metopimazine

1. Six healthy volunteers were given single oral doses of the antiemetic metopimazine (MPZ), starting with trial (a) 20 mg preprandially and followed by trial (b) 50 mg preprandially. In trials (c) and (d) the doses were similar to those in trials (a) and (b), but MPZ was given postprandially. To evaluate intra-individual variation in serum concentrations, trial (a) was repeated three times in four of the volunteers (trial (e)). 2. Blood samples were drawn and the serum concentrations of MPZ and its acid metabolite (AMPZ) were measured by h.p.l.c. 3. There was no evidence of dose-dependent kinetics at the dose levels studied. 4. Median AUC values were 22.6, 16.2, 52.4 and 35.2 (trials (a), (b), (c) and (d), ng ml-1 h). Food intake decreased the serum concentrations of MPZ, suggesting that MPZ should be taken preprandially.

Malignant disease: nutritional implications of disease and treatment

Protein-energy malnutrition (PEM) is common in cancer patients and may develop into the syndrome known as 'cancer cachexia'. This is characterised by complex disturbances in carbohydrate, lipid, protein, and electrolyte metabolism. The aetiology is equally complex, with host and therapeutic factors contributing to the reduced food intake and effects on host tissues. Anorexia is of prime importance, differing in its cause from one patient to another and often presenting a barrier to successful nutritional support. Further research is necessary to elucidate the interaction of central and peripheral factors that may be involved in the aetiology of anorexia. Because of the interplay of biochemical, physiological, and psychological consequences of cancer, the nutritional support of the patient presents a considerable challenge to the caring professions.

[Small intestinal absorption in cancer patients--basis for enteral feeding therapy in oncology]

A deteriorating nutritional condition combined with the loss of body mass is one of the most noticeable symptoms of cancer. In order to answer the question to what extent absorption disorders in the small intestine are responsible for the malnutrition which develops, we studied 54 oncologic patients using modified D-xylose absorption tests. After the oral and intravenous administration of 10 g D-xylose at different times, the degree of absorption dependent on time was determined on the basis of a biophysical model. When accompanied by general nonspecific tumor symptoms, the frequency of absorption restrictions was increased. An established relation was found between the extent of small intestinal absorption, on the one hand, and the degree of spreading (staging) and the degree of histological differentiation of the carcinoma, on the other hand. Enteral absorption disorders represent a partial cause for the development of malnutrition in cancer patients and must be viewed as a result of a metabolic situation which is distinctly catabolic.

Nutrition and cancer

Nutrition and cancer interact at several levels. Both dietary deficiencies and dietary excesses have been linked with changes in prevalence of certain human cancers. With respect to one particular nutrient, riboflavin, a dietary deficiency may decrease the development of spontaneous tumors in experimental animals but increase carcinogenesis due to certain agents. Cancer itself has profound effects upon nutritional status, and neoplastic tissue appears in general to resist dietary deficiency more effectively than normal tissues. Nutrition has a major role in therapy of cancer, but as an adjunct to the treatment plan rather than as an alternative. Parenteral nutrition, either peripheral or total, can provide support that is critically needed when patients cannot eat or swallow, have obstruction or malabsorption, or are otherwise unable to utilize dietary nutrients in adequate amounts. The advent of home parenteral nutrition now provides a means for long-term rehabilitation of cancer patients.

Alterations in gastrointestinal steady-state kinetics associated with the growth of experimental tumours

Changes in the growth kinetics of the intestinal epithelium were observed in mice bearing the Lewis lung carcinoma and the T1699 mammary adenocarcinoma and in rats bearing the H-4-II-E2 hepatoma. Proliferative activity in the jejunal tissue was markedly depressed with increasing tumour burden. Simultaneously, a significant reduction in total crypt cellularity occurred, followed by a reduction in villus height. While the total number of proliferative cells per crypt decreased, the relative proliferative compartment within the shrinking crypt increased. The rate of mucosal DNA synthesis remained constant during the initial cytokinetic changes, falling only after proliferative activity of the intestine was reduced to less than 50% of control levels. No general correlation could be drawn from the three tumour models studied between the level of gastrointestinal proliferation and tumour size, tumour growth rate or loss of weight by the tumour-bearing animals. However, intestinal proliferation was reduced by 50% when the tumour burden for each of the three tumours reached 6--8% of the host animal weight.

Effects of cancer on nutrition: impaired organ system effects

The specific organ system effects of cancer and its treatment have been reviewed from the standpoint of nutritional impact. Nutritional impairment may occur as the result of specific organ system malfunction, and malnutrition itself may impair organ system functions in such a way as to compound these deficits. Nonmalignant, acute, and chronic illnesses resemble cancer in many ways, particularly in their ability to produce malnutrition and these organ system malfunctions. It is apparent that there is nothing particularly unique about many of these cancer states, from the standpoint of nutritional deficiency, that is not found in nonneoplastic conditions.