Connections between cross-tissue and intra-tissue biomarkers of aging biology in older adults

Background

Saliva measures are generally more accessible than blood, especially in vulnerable populations. However, connections between aging biology biomarkers in different body tissues remain unknown.

Methods

The present study included individuals (N = 2406) who consented for saliva and blood draw in the Health and Retirement Telomere length study in 2008 and the Venous blood study in 2016 who had complete data for both tissues. We assessed biological aging based on telomere length in saliva and DNA methylation and physiology measures in blood. DNA methylation clocks combine information from CpGs to produce the aging measures representative of epigenetic aging in humans. We analyzed DNA methylation clocks proposed by Horvath (353 CpG sites), Hannum (71 CpG sites), Levine or PhenoAge, (513 CpG sites), GrimAge, (epigenetic surrogate markers for select plasma proteins), Horvath skin and blood (391 CpG sites), Lin (99 CpG sites), Weidner (3 CpG sites), and VidalBralo (8 CpG sites). Physiology measures (referred to as phenotypic age) included albumin, creatinine, glucose, [log] C-reactive protein, lymphocyte percent, mean cell volume, red blood cell distribution width, alkaline phosphatase, and white blood cell count. The phenotypic age algorithm is based on parametrization of Gompertz proportional hazard models. Average telomere length was assayed using quantitative PCR (qPCR) by comparing the telomere sequence copy number in each patient's sample (T) to a single-copy gene copy number (S). The resulting T/S ratio was proportional to telomere length, mean. Within individual, relationships between aging biology measures in blood and saliva and variations according to sex were assessed.

Results

Saliva-based telomere length showed inverse associations with both physiology-based and DNA methylation-based aging biology biomarkers in blood. Longer saliva-based telomere length was associated with 1 to 4 years slower biological aging based on blood-based biomarkers with the highest magnitude being Weidner (β = - 3.97, P = 0.005), GrimAge (β = - 3.33, P < 0.001), and Lin (β = - 3.45, P = 0.008) biomarkers of DNA methylation.

Conclusions

There are strong connections between aging biology biomarkers in saliva and blood in older adults. Changes in telomere length vary with changes in DNA methylation and physiology biomarkers of aging biology. We observed variations in the relationship between each body system represented by physiology biomarkers and biological aging, particularly at the DNA methylation level. These observations provide novel opportunities for integration of both blood-based and saliva-based biomarkers in clinical care of vulnerable and clinically difficult to reach populations where either or both tissues would be accessible for clinical monitoring purposes.

Body mass index and Mini Nutritional Assessment-Short Form as predictors of in-geriatric hospital mortality in older adults with COVID-19

BACKGROUND & AIMS

Overweight and obesity have been consistently reported to carry an increased risk for poorer outcomes in coronavirus disease 2019 (COVID-19) in adults. Existing reports mainly focus on in-hospital and intensive care unit mortality in patient cohorts usually not representative of the population with the highest mortality, i.e. the very old and frail patients. Accordingly, little is known about the risk patterns related to body mass and nutrition in very old patients. Our aim was to assess the relationship between body mass index (BMI), nutritional status and in-geriatric hospital mortality among geriatric patients treated for COVID-19. As a reference, the analyses were performed also in patients treated for other diagnoses than COVID-19.

METHODS

We analyzed up to 10,031 geriatric patients with a median age of 83 years of which 1409 (14%) were hospitalized for COVID-19 and 8622 (86%) for other diagnoses in seven geriatric hospitals in the Stockholm region, Sweden during March 2020-January 2021. Data were available in electronic hospital records. The associations between 1) BMI and 2) nutritional status, assessed using the Mini-Nutritional Assessment - Short Form (MNA-SF) scale, and short-term in-geriatric hospital mortality were analyzed using logistic regression.

RESULTS

After adjusting for age, sex, comorbidity, polypharmacy, frailty and the wave of the pandemic (first vs. second), underweight defined as BMI<18.5 increased the risk of in-hospital mortality in COVID-19 patients (odds ratio [OR] = 2.30; confidence interval [CI] = 1.17-4.31). Overweight and obesity were not associated with in-hospital mortality. Malnutrition; i.e. MNA-SF 0-7 points, increased the risk of in-hospital mortality in patients treated for COVID-19 (OR = 2.03; CI = 1.16-3.68) and other causes (OR = 6.01; CI = 2.73-15.91).

CONCLUSIONS

Our results indicate that obesity is not a risk factor for very old patients with COVID-19, but emphasize the role of underweight and malnutrition for in-hospital mortality in geriatric patients with COVID-19.

Technological readiness and implementation of genomic-driven precision medicine for complex diseases

The fields of human genetics and genomics have generated considerable knowledge about the mechanistic basis of many diseases. Genomic approaches to diagnosis, prognostication, prevention and treatment - genomic-driven precision medicine (GDPM) - may help optimize medical practice. Here, we provide a comprehensive review of GDPM of complex diseases across major medical specialties. We focus on technological readiness: how rapidly a test can be implemented into health care. Although these areas of medicine are diverse, key similarities exist across almost all areas. Many medical areas have, within their standards of care, at least one GDPM test for a genetic variant of strong effect that aids the identification/diagnosis of a more homogeneous subset within a larger disease group or identifies a subset with different therapeutic requirements. However, for almost all complex diseases, the majority of patients do not carry established single-gene mutations with large effects. Thus, research is underway that seeks to determine the polygenic basis of many complex diseases. Nevertheless, most complex diseases are caused by the interplay of genetic, behavioural and environmental risk factors, which will likely necessitate models for prediction and diagnosis that incorporate genetic and non-genetic data.

Joint impact of common risk factors on incident dementia: A cohort study of the Swedish Twin Registry

BACKGROUND

As common risk factors of dementia, nine factors (low education, hearing loss, obesity, hypertension, smoking, depression, physical inactivity, diabetes and social isolation) were proposed. However, the joint impact of these factors on incident dementia is still uncertain; hence, we aimed to examine this impact.

METHODS

We conducted a cohort study of 9017 cognitively intact individuals aged ≥ 65 years in the Swedish Twin Registry. The main exposure was the total number of reported risk factors (ranging from 0 to 9). Data on dementia diagnoses were based on clinical workup and national health registers. After estimating the adjusted hazard ratios of incident dementia, the population attributable fraction (PAF) was calculated. We then conducted additional analyses, including APOE ε4 status in a genotyped subsample (n = 2810) to check the relative impact of the main exposure and discordant twin pair (n = 1158) analysis to consider confounding by familial effects (shared genetic or familial environmental factors).

RESULTS

The number of dementia cases was 1950 (21.6%). A dose-response relationship between the number of risk factors and incident dementia was observed; hazard ratio (95% confidence interval) per one-unit increment in number of risk factors was 1.07 (1.03 to 1.11). The PAF for the combination of the nine risk factors was 10.4%. The PAF of all nine risk factors was smaller than that of APOE ε4 genotype (20.8%) in the subsample. Discordant pair analysis suggested that the observed association was not likely explained by familial effects.

CONCLUSION

The nine risk factors may have considerable impact as modifiable factors on incident dementia.

Plasma concentrations of etonogestrel in women using oral desogestrel before and after Roux-en-Y gastric bypass surgery: a pharmacokinetic study

OBJECTIVE

To investigate whether Roux-en-Y gastric bypass (RYGB) affects oral desogestrel (etonogestrel) pharmacokinetics.

DESIGN

Single centre, open label, phase-2 pharmacokinetic study.

SETTING

University hospital of Linköping, Sweden.

POPULATION

Fourteen women with planned RYGB surgery were included; nine women aged 18-45 years using 75 micrograms desogestrel completed the study.

METHODS

Steady-state etonogestrel pharmacokinetic (PK) parameters were measured on three occasions for each individual (at 8 ± 6 weeks before surgery, and at 12 ± 2 and 52 ± 2 weeks after surgery). Each patient served as her own control. On each occasion, serum samples were collected during a 24-hour period and etonogestrel concentrations were determined with ultra-performance liquid chromatography/tandem mass spectrometry.

MAIN OUTCOME MEASURES

Area under the plasma concentration time curve of etonogestrel (AUC_{0-24 hours} ).

RESULTS

All women had significant postoperative weight loss. There were no significant differences in AUC_{0-24 hours} , terminal half-lives (t_½ ), time to peak serum concentrations (T_max ), or apparent oral clearances of etonogestrel (CL_oral ) before and after gastric bypass surgery on any occasion. Peak serum concentrations (C_max ) increased after 52 ± 2 weeks compared with preoperative values (0.817 ng/ml versus 0.590 ng/ml, P = 0.024).

CONCLUSION

To our knowledge, this is the first study to investigate the effects on desogestrel pharmacokinetics after RYGB. This study did not reveal any clinically significant changes in etonogestrel pharmacokinetics, suggesting that oral desogestrel may be used by women after RYGB surgery. The sample size was limited, however, and therefore the results should be interpreted cautiously.

TWEETABLE ABSTRACT

The pharmacokinetics of oral desogestrel does not appear to change after gastric bypass surgery.

Genetic susceptibility to cardiovascular disease and risk of dementia

Several studies have shown cardiovascular disease (CVD) to be associated with dementia, but it is not clear whether CVD per se increases the risk of dementia or whether the association is due to shared risk factors. We tested how a genetic risk score (GRS) for coronary artery disease (CAD) affects dementia risk after CVD in 13 231 Swedish twins. We also utilized summarized genome-wide association data to study genetic overlap between CAD and Alzheimer´s disease (AD), and additionally between shared risk factors and each disease. There was no direct effect of a CAD GRS on dementia (hazard ratio 0.99, 95% confidence interval (CI): 0.98-1.01). However, the GRS for CAD modified the association between CVD and dementia within 3 years of CVD diagnosis, ranging from a hazard ratio of 1.59 (95% CI: 1.05-2.41) in the first GRS quartile to 1.91 (95% CI: 1.28-2.86) in the fourth GRS quartile. Using summary statistics, we found no genetic overlap between CAD and AD. We did, however, find that both AD and CAD share a significant genetic overlap with lipids, but that the overlap arose from clearly distinct gene clusters. In conclusion, genetic susceptibility to CAD was found to modify the association between CVD and dementia, most likely through associations with shared risk factors.

Serum selenium in relation to measures of glucose metabolism and incidence of Type 2 diabetes in an older Swedish population

AIMS

The relation between selenium status and risk of Type 2 diabetes is controversial. We aimed to evaluate associations of serum selenium, a marker of dietary selenium, with measures of glucose metabolism and risk of diabetes.

METHODS

We used data from a population-based, longitudinal cohort of 1925 Swedish men who were 50 years old and did not have diabetes at baseline in the 1970s. At baseline, an intravenous glucose tolerance test was performed and, at a follow-up examination after 20 years, an oral glucose tolerance test and a hyperinsulinaemic euglycaemic clamp for the assessment of insulin sensitivity were conducted.

RESULTS

At baseline, the mean (standard deviation) selenium concentration was 75.6 (14.3) μg/l. During 20 years of follow-up, 88 incident cases of diabetes occurred in 1024 participants with follow-up data. Baseline serum selenium levels were not associated with risk of diabetes (odds ratio 1.06; 95% CI 0.83-1.38). Higher selenium levels were associated with lower early insulin response (standardized β -0.08; 95% CI -0.14 to -0.03) at baseline after adjusting for potential confounders, but not with any other measures of β-cell function or insulin sensitivity at baseline or follow-up. The association with early insulin response was non-significant after taking multiple testing into account.

CONCLUSIONS

Our results do not support a role of dietary selenium in the development of disturbances in glucose metabolism or diabetes in older individuals.

Variation in genes in the endothelin pathway and endothelium-dependent and endothelium-independent vasodilation in an elderly population

AIM

Indirect evidences by blockade of the endothelin receptors have suggested a role of endothelin in endothelium-dependent vasodilation. This study aimed to investigate whether circulating levels of endotehlin-1 or genetic variations in genes in the endothelin pathway were related to endothelium-dependent vasodilation.

METHODS

In 1016 seventy-year-old participants of the population-based Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study (52% women), we measured endothelium-dependent vasodilation using the invasive forearm technique with acetylcholine given in the brachial artery (EDV) and the brachial artery ultrasound technique with measurement of flow-mediated dilatation (FMD). Plasma endothelin-1 levels were measured and 60 SNPs in genes in the endothelin pathway (ECE1, EDN1, EDNRA, EDNRB) were genotyped.

RESULTS

No significant associations were found between circulating endothelin levels and EDV or FMD. No single genotype was related to EDV or FMD following adjustment for multiple testing, but a genotype score for 3 SNPs (rs11618266 in EDNRB, rs17675063 in EDNRA, rs3026868 in ECE1) was significantly related to EDV (beta coefficient 0.070, 95% CI 0.025-0.12, P = 0.002) when adjusting for gender, systolic blood pressure, HDL and LDL cholesterol, serum triglycerides, BMI, diabetes, smoking, antihypertensive medication or statins and CRP. This score was also related to nitroprusside-induced vasodilation in the forearm.

CONCLUSION

A combination of genotypes in the endothelin pathway was related to both endothelium-dependent and endothelium-independent vasodilation in forearm resistance vessels, but not in the brachial artery in an elderly population, giving evidence for a role of the endothelin system in resistance vessel reactivity independent of major cardiovascular risk factors.

Utilization pattern of metamizole in northern Sweden and risk estimates of agranulocytosis

OBJECTIVE

This study was carried out in order to investigate the utilization pattern of metamizole to better estimate the quantitative risk of agranulocytosis since a cluster of such cases have been observed in Sweden.

METHODS

Cases of agranulocytosis submitted to the Swedish Adverse Drug Reactions Advisory Committee (SADRAC) between 1996 and 1999 were identified. Based on the utilization pattern of metamizole in inpatients at three hospitals and in outpatients in two counties in northern Sweden risk estimates of agranulocytosis during metamizole treatment were estimated. The utilization of metamizole was investigated by scanning 3567 case records at 10 hospital departments as well as stored prescriptions at six pharmacies during a 3-month study period.

RESULTS

Ten cases of agranulocytosis during treatment with metamizole have been reported to SADRAC over the period 1996 to 1999. During the 3-month study period metamizole was prescribed to 666 (19%) inpatients. Of these, approximately 96% received the drug for less than 1 week, 7.2% had used the drug previously. At the participating pharmacies 112 metamizole prescriptions for outpatients were found. The drug was prescribed in 34% for less than 1 week, in 28% for 7-15 days, and in 38% for more than 15 days. The mean prescribed daily dose was 2.7 g. Given certain assumptions including the actual amounts prescribed the calculated risks of agranulocytosis would be approximately one out of every 31,000 metamizole-treated inpatients and one of every 1400 metamizole-treated outpatients.

CONCLUSION

This study indicates that in most inpatients the use of metamizole in northern Sweden was within the approved indications for the drug. However, a considerable number of outpatients received the drug for a longer time than recommended and this may carry an increased risk for developing agranulocytosis.

The major fluvoxamine metabolite in urine is formed by CYP2D6

OBJECTIVE

Previous studies have shown that fluvoxamine is metabolized by CYP1A2 and CYP2D6, but there is no information on the impact the various CYP enzymes have on the different metabolic pathways of fluvoxamine biotransformation. The present study was designed to investigate this issue.

METHODS

The major fluvoxamine metabolite, the 5-demethoxylated carboxylic acid metabolite, was analyzed in urine from 50 healthy volunteers after intake of a single oral dose of 50 mg fluvoxamine, and the formation clearance for the metabolite (CLm) was calculated. Of the subjects, 28 were non-smoking CYP2D6 and CYP2C19 extensive metabolizers (EMs), 12 were smokers and were thus considered to have an induced CYP1A2 activity, 5 were CYP2D6 poor metabolizers (PMs), and 5 were CYP2C19 PMs. In 11 of the non-smoking EMs, 200 mg caffeine was given at another occasion in order to calculate oral caffeine clearance as a measure of CYP1A2 activity. In addition, CLm was calculated in ten other subjects given increasing doses of fluvoxamine for 4 weeks.

RESULTS

Oral clearance of fluvoxamine was significantly higher in smokers, and significantly lower in CYP2D6 PMs than in non-smoking EMs. CLm was 78% lower in CYP2D6 PMs than in the EMs. Smoking and being a CYP2C19 PM did not influence CLm. There was no significant correlation between oral caffeine clearance and CLm. CLm decreased with increasing fluvoxamine dosage, but the decrease in oral clearance was even higher.

CONCLUSION

These results indicate that CYP2D6 catalyzes the major metabolic pathway of fluvoxamine, whereas CYP1A2 seems to catalyze other less important pathways. Both the CYP2D6 and the CYP1A2 pathways seem to be saturated in parallel with increasing fluvoxamine dosage.

Leptin concentrations are increased in subjects treated with clozapine or conventional antipsychotics

BACKGROUND

Overweight is a considerable clinical problem in patients treated with antipsychotic agents. Recent results suggest that insulin resistance with increased insulin levels is also associated with treatment with the atypical antipsychotic agent clozapine. Leptin is important for the control of body weight and has been proposed to be a link between obesity and the insulin resistance syndrome. This study examined if clozapine-treated subjects and subjects treated with conventional antipsychotics had increased leptin levels compared with the general population and whether there was a gender difference in this respect.

METHOD

Clozapine-treated patients (N = 41), patients treated with conventional antipsychotic drugs (N = 62), and healthy subjects from the Northern Sweden Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) project (N = 189) were investigated with a cross-sectional study design. Weight, body mass index (BMI), and plasma leptin concentrations were measured, and all study subjects were investigated for the presence of diabetes mellitus. Drug treatment, health status, and smoking habits were registered.

RESULTS

After adjustment for gender, BMI, smoking habits, age, and diabetes, hyperleptinemia was independently (p < .001) associated with clozapine treatment and with treatment with conventional antipsychotics (p < .005) within a multiple regression analysis. In separate multiple regression analyses, leptin levels were significantly associated with clozapine treatment in men (p = .002) and women (p =.023) and with conventional antipsychotic treatment in men (p = .027) but not in women.

CONCLUSION

Treatment with clozapine as well as with conventional antipsychotics is associated with increased levels of circulating leptin. Hyperleptinemia can be an important link in the development of overweight and the insulin resistance syndrome in subjects receiving antipsychotic drugs, especially atypical agents like clozapine.

Olanzapine disposition in humans is unrelated to CYP1A2 and CYP2D6 phenotypes

OBJECTIVE

Limited data suggest that CYP1A2 and CYP2D6 are involved in the metabolism of olanzapine. The purpose of this study was to further elucidate the role of these enzymes in the disposition of olanzapine in vivo.

METHODS

Seventeen healthy non-smoking male volunteers were included in the study. Five subjects were CYP2D6 poor metabolisers (PMs), and 12 were CYP2D6 extensive metabolisers (EMs). All subjects received a single oral dose of 7.5 mg olanzapine, and serum concentrations were measured for 96 h using gas chromatography. A cross-over study was undertaken in the 12 CYP2D6 EMs who at least 2 weeks before or after the olanzapine dose received a single oral dose of 200 mg caffeine. The concentrations of caffeine and paraxanthine were measured in saliva 10 h after caffeine intake, and the paraxanthine/caffeine ratio was calculated as a measure of CYPIA2 activity.

RESULTS

A threefold inter-individual variability in oral clearance (CLoral) and maximum serum concentration (Cmax) of olanzapine was observed and a 2.3-fold inter-individual variability in CYPIA2 activity. There was no significant correlation between CYP1A2 activity and oral clearance of olanzapine (r=-0.19, P=0.56). Moreover, there were no significant differences in any of the olanzapine pharmacokinetic parameters between the CYP2D6 PMs and EMs (CLoral=0.246 l h(-1) kg(-1) and 0.203 l h(-1) kg(-1), respectively, P=0.30).

CONCLUSION

Neither CYP1A2 nor CYP2D6 seem to have a dominating role in olanzapine biotransformation after intake of a single dose.

Myocarditis related to clozapine treatment

Myocarditis has in several case reports been associated with use of clozapine. Eight cases of myocarditis during treatment with clozapine that were submitted to the Swedish Adverse Drug Reaction Advisory Committee and 18 cases that were reported in the literature are summarized. As part of the routine signal detection process on the World Health Organization (WHO) Program on International Drug Monitoring database, which contains more than two million case reports of spontaneously reported suspected adverse drug reactions, a Bayesian confidence propagation neural network (BCPNN) is used. This article also shows the retrospective output of the BCPNN over time for clozapine and myocarditis and discusses its implications. In 19 (79%; duration of treatment not stated for 2 patients) of 24 patients with myocarditis, the symptoms occurred within the first 6 weeks of clozapine treatment. Many patients shared a similar clinical course, with symptoms such as an influenza-like illness, fever, sinus tachycardia, hypotension, chest discomfort, and heart failure. The reaction was fatal in 12 (46%) of these patients. The other patients generally had a prompt recovery. By using the BCPNN technique, a quantitative association between clozapine and myocarditis was demonstrated, and the association might have been high-lighted for clinical review in 1994 had this BCPNN method been in use at the WHO center at the time. Myocarditis seems to be a rare and potentially lethal adverse effect of clozapine. Admittance for observation, interruption of the clozapine treatment, and treatment with corticosteroids should be considered for patients in whom this reaction is suspected.

Influence of gender and oral contraceptives on CYP2D6 and CYP2C19 activity in healthy volunteers

AIMS

The study was carried out in order to assess the effects of gender and the use of oral contraceptives (OCs) on CYP2D6 and CYP2C19 activities in healthy volunteers.

METHODS

Six hundred and eleven Caucasian volunteers (330 males and 281 females; age range 18-49 years) were phenotyped with respect to CYP2D6 and CYP2C19 by means of the probe drugs dextromethorphan and mephenytoin, respectively. Extensive metabolisers were selected for this study.

RESULTS

The median dextromethorphan/dextrorphan metabolic ratio in non-OC using females was significantly lower than in males (0.067 vs 0.080; P = 0.033) (mean difference in ln dextromethorphan/dextrorphan metabolic ratio 0.023, 95% CI 0.03-0.43). For the mephenytoin S/R ratio, no such difference was observed. However, OC using females had a significantly higher median mephenytoin S/R ratio than non-OC using females (0.230 vs 0.090; P < 0.001) (mean difference in ln mephenytoin S/R ratio 0.082, 95% CI 0.60-1.04). Moreover, females using combined OCs had a significantly higher median ratio than females using OCs with progestins only (median 0.258 vs 0.135; P = 0.008) (mean difference in ln mephenytoin S/R ratio 0.82, 95% CI 0.21-1.34).

CONCLUSIONS

Given certain assumptions, the study indicates that females in the fertile age have a slightly higher CYP2D6 activity compared with males. There was no evidence of a gender difference in CYP2C19 activity. The use of combined OCs reduces the activity of CYP2C19, an effect that seems to be related to the ethinyloestradiol component.

Citalopram pharmacokinetics in patients with chronic renal failure and the effect of haemodialysis

OBJECTIVE

To study the effects of severe renal failure and haemodialysis on the pharmacokinetics of citalopram.

METHODS

Four patients with renal failure undergoing haemodialysis and eight healthy controls were given a single dose of citalopram. The concentrations of citalopram and its metabolites desmethylcitalopram and didesmethylcitalopram were measured in serum and urine. On a different day, the four patients undergoing haemodialysis were given another single dose of citalopram, and the drug concentrations were measured in serum from the artery leading to the dialyser and in the dialysate. In addition, one anuric patient treated with citalopram on a regular basis was included in the study.

RESULTS

There were no significant differences between the two groups in any of the pharmacokinetic parameters with the exception of the renal clearance of citalopram, which was significantly lower in the renal failure group than in the control group (1.70 ml/min versus 66.2 ml/min, P<0.001). Oral clearance of citalopram was almost identical in the two groups (452 ml/min versus 456 ml/min). The process of haemodialysis cleared about 1% of the dose as citalopram and 1% as desmethylcitalopram only.

CONCLUSION

Severe renal failure does not affect the pharmacokinetics of citalopram and modification of the usual citalopram dose does thus not seem to be necessary. The contribution of haemodialysis to the total elimination of citalopram is negligible.

Anticonvulsant use during lactation

The issue of prescribing anticonvulsant drugs during lactation is clinically important, but also complex. Data for some drugs are completely lacking and for other drugs information is only available from single dose or short term studies or case reports. Moreover, limited knowledge exists about the practical impact of the drug concentrations found in breast milk and there are great methodological problems in the assessment of possible adverse drug reactions in infants. Nevertheless, based on current knowledge, some recommendations can be suggested. Treatment with carbamazepine, valproic acid (sodium valproate) and phenytoin is considered compatible with breastfeeding. Treatment with ethosuximide or phenobarbital (phenobarbitone)/primidone should most probably be regarded as potentially unsafe and close clinical monitoring of the infant is recommended if it is decided to continue breastfeeding. Occasional or short term treatment with benzodiazepines could be considered as compatible with breastfeeding, although maternal diazepam treatment has caused sedation in suckling infants after short term use. During long term use of benzodiazepines, infants should be observed for signs of sedation and poor suckling. Only very limited clinical data are available for the new generation anticonvulsant drugs and no clearcut recommendations can be made until further data are present. If it is decided to continue breast feeding during treatment with these drugs, the infant should be monitored for possible adverse effects. In general, the drug should be given in the lowest effective dose, guided by maternal serum or plasma drug concentration monitoring. If breast feeding is avoided at times of peak drug levels in milk, the exposure of the infant can be reduced to some extent. As breast milk has considerable advantages over formula milk, the benefits of continuing breast feeding should always be taken into consideration in the risk-benefit analysis.

Analgesics and breast-feeding: safety considerations

The issue of prescription of analgesics during lactation is clinically important but also complex. Most of the information available is based on single dose or short term studies, and for many drugs only a single or a few case reports have been published. As great methodological problems exist in the assessment of possible adverse drug reactions in neonates and infants, there is limited knowledge about the practical impact of the, often very low, concentrations found. Nevertheless, some recommendations can be made. Breast-feeding during maternal treatment with paracetamol (acetaminophen) should be regarded as being safe. Short term use of nonsteroidal anti-inflammatory drugs seems to be compatible with breast-feeding. For long term treatment, short-acting agents without active metabolites, such as ibuprofen, should possibly be preferred. The use of aspirin (acetylsalicylic acid) in single doses should not pose any significant risks to the suckling infant. Use of codeine is probably compatible with breast-feeding, although the effects of long term exposure have not been fully elucidated. For propoxyphene, it seems unlikely that the suckling infant will ingest amounts that will cause any detrimental effects during short term treatment. However, it cannot be excluded that significant amounts of the metabolite norpropoxyphene may arise in the suckling infant during long term exposure. Treatment of the mother with single doses of morphine or pethidine (meperidine) is not expected to cause any risk for the suckling infant. Repeated administration of pethidine, in contrast to morphine, affects the suckling infant negatively. Thus, morphine should be preferred in lactating mothers. However, during long term treatment with morphine, the importance of uninterrupted breast-feeding should be assessed on an individual basis against the potential risk of adverse drug effects in the infant. If it is decided to continue breast-feeding the infant should be observed for possible adverse effects. In general, if treatment of a lactating mother with an analgesic drug is considered necessary, the lowest effective maternal dose should be given. Moreover, infant exposure can be further reduced if breast-feeding is avoided at times of peak drug concentration in milk. As breast milk has considerable nutritional, immunological and other advantages over formula milk, the possible risks to the infant should always, and on an individual basis, be carefully weighed against the benefits of continuing breast-feeding.

Association of venous thromboembolism and clozapine

Data from the Swedish Adverse Reactions Advisory Committee suggest that use of clozapine is associated with venous thromboembolic complications. We summarise 12 cases of thromboembolism during clozapine treatment. In five cases the outcome was fatal.

Effect of caffeine on clozapine pharmacokinetics in healthy volunteers

AIMS

To assess the effects of caffeine on the pharmacokinetics of clozapine in healthy volunteers.

METHODS

This was an open label randomized crossover study in 12 nonsmoking healthy male volunteers. The subjects received a single oral dose of 12.5 mg clozapine in each phase with or without concomitant intake of caffeine (mean dose: 550 mg day-1, range: 400-1000 mg day-1 ). Serum concentrations of clozapine and its metabolites desmethyl-clozapine and clozapine-N-oxide were measured during a 48 h period in each phase. In addition, serum concentrations of caffeine and the metabolite paraxanthine were monitored.

RESULTS

A 19% increase in mean clozapine AUC(0,infinity) (P=0.05) and a 14% decrease of mean oral clearance of clozapine were observed during concomitant intake of caffeine (P=0.05) compared with intake of only clozapine. Statistically significant decreases of mean ratios between AUC(0, 12h) for desmethyl-clozapine and AUC(0,12h) for clozapine (-18%), and between AUC(0,12h) for clozapine-N-oxide and AUC(0,12h) for clozapine (-23%) were observed during the caffeine phase (P=0.03 and 0.02, respectively). Oral clearance of clozapine and the ratio AUC(0, 12h) for desmethyl-clozapine/AUC(0,12h) for clozapine were correlated with the paraxanthine/caffeine ratio in serum after intake of caffeine (rs=0.62; P=0.03 and rs=0.77; P=0.003, respectively).

CONCLUSIONS

These results suggest that caffeine in daily doses of 400-1000 mg inhibits the metabolism of clozapine to an extent that might be clinically significant in certain individuals.

Enhanced platelet serotonin 5-HT2A receptor binding in anorexia nervosa and bulimia nervosa

Some evidence exists to suggest that serotonin 5-HT2A receptor function is altered in anorexia nervosa and bulimia nervosa. In order to further investigate the 5-HT2A receptor in eating disorders, platelet [3H]lysergic acid diethylamide ([3H]LSD) binding was studied in ten patients with anorexia nervosa, 23 patients with bulimia nervosa and 33 healthy controls. At admission, Bmax for platelet [3H]LSD binding was significantly higher both in the anorexia nervosa group (30.6+/-4.2 fmol/mg protein; mean+/-S.D.) and in the bulimia nervosa group (30.8+/-7.6 fmol/mg protein) than in the control group (23.5+/-6.3 fmol/mg protein; p=0.01 and p=0.003, respectively). Kd was borderline significantly higher among anorexics (median 1.45 nM) and significantly higher among bulimics (median 1.66 nM) than among controls (median 0.95 nM; p=0.05 and 0.003, respectively). The Global Assessment of Functioning score and the body mass index were both significantly negatively correlated to Kd (r=-0.40; p=0.03 and r=-0.41 p=0.03, respectively), but not to Bmax. The present study indicates that patients with anorexia nervosa as well as patients with bulimia nervosa have an enhanced 5-HT2A receptor binding and provides further evidence for a serotonergic dysfunction in eating disorders.

Excretion of paroxetine into breast milk

BACKGROUND

The study was carried out to quantify the excretion of the selective serotonin reuptake inhibitor paroxetine in breast milk.

METHOD

In 6 lactating women, the concentrations of paroxetine in breast milk and serum were studied at the times for assumed minimum (24 hours after dose intake) and maximum (4-7 hours after dose intake) drug levels in milk. Moreover, a seventh subject was studied with frequent and regular sampling throughout a dose interval of 24 hours at 2 different dose levels.

RESULTS

The mean milk/serum concentration ratios in the first 6 subjects ranged from 0.39 to 1.11 (overall mean +/- SD = 0.69 +/- 0.29), and the mean estimated dose to the infants ranged from 0.7% to 2.9% (overall mean +/- SD = 1.4% +/- 0.79%) of the weight-adjusted maternal dose. Based on area-under-the-curve data from the seventh subject, the milk/serum concentration ratio was 0.69 at a dose of 20 mg/day and 0.72 at a dose of 40 mg/day; the estimated relative doses to the infant were 1.0% and 2.0%, respectively. The mean increase in milk paroxetine concentrations from assumed minimum to assumed maximum was 61% (range, 4%-172%; p < .01). The mean paroxetine concentration in hindmilk was 78% higher than in foremilk (range, 16%-169%; p < .01), an increase that was parallel to the increase in milk triglyceride levels (r = 0.83, p = .005). No adverse drug reactions or unusual behaviors were reported in the infants.

CONCLUSION

The study indicates that the relative dose to a suckling infant for paroxetine is lower than that reported for fluoxetine and citalopram and higher than that reported for sertraline and fluvoxamine.

Absence of interaction between erythromycin and a single dose of clozapine

OBJECTIVE

To study the suggested pharmacokinetic interaction between erythromycin, a strong inhibitor of CYP3A4, and clozapine.

METHODS

Twelve healthy male volunteers received a single dose of 12.5 mg of clozapine alone or in combination with a daily dose of 1500 mg erythromycin in a randomised crossover study. Clozapine and its metabolites clozapine-N-oxide and desmethyl-clozapine were measured in serum samples which were collected during a 48 h period and in a sample of the urine secreted over the interval 0-12 h.

RESULTS

There were no significant differences in mean area under the serum concentration time curves (1348 (633) nmol h x l(-1) in the control phase and 1180 (659) nmol h x l(-1) in the erythromycin phase), terminal halflives (19 (13) h and 15 (6) h, respectively), peak serum concentrations (92 (53) nmol x l(-1) and 77 (40) nmol x l(-1), respectively), time to peak serum concentrations (1.4 (0.7) h and 1.5 (1.0) h, respectively) or apparent oral clearances of clozapine (34 (15) l x h(-1) and 46 (37) l x h(-1), respectively). There were no significant differences in partial metabolic clearances to clozapine-N-oxide (5.1 (3.6) l x h(-1) and 7.8 (9.4) l x h(-1), respectively) or to desmethyl-clozapine (1.5 (1.3) l x h(-1) and 1.8 (1.7) l x h(-1), respectively) or in renal clearances of clozapine (0.8 (0.5) l x h(-1) and 1.0 (0.7) l x h(-1), respectively) between the two phases.

CONCLUSION

These results demonstrate that erythromycin at a clinically relevant dosage does not inhibit the metabolism of clozapine. Hence, CYP3A4 seems to be of minor importance in the disposition of clozapine in humans at least when clozapine is taken at a low single dose.

Lack of correlation between fluvoxamine clearance and CYP1A2 activity as measured by systemic caffeine clearance

OBJECTIVE

Evidence exists to suggest that fluvoxamine is metabolized by CYP1A2. The present study was undertaken in order to further elucidate the role of CYPIA2 in fluvoxamine disposition.

METHODS

Twelve healthy non-smoking male volunteers participated in this cross-over study. Six subjects received first fluvoxamine 50 mg as a single oral dose and, some weeks later, caffeine 200 mg as a single oral dose. The other six subjects received the drugs in reverse order. Serum concentrations of fluvoxamine, caffeine and paraxanthine were measured and standard pharmacokinetic parameters were calculated.

RESULTS

There were no significant correlations between caffeine clearance and fluvoxamine oral clearance (rs = -0.30; P = 0.43) or between the paraxanthine/caffeine ratio in serum 6 h after caffeine intake and fluvoxamine oral clearance (rs = -0.18; P = 0.58).

CONCLUSION

CYP1A2 does not appear to be of major importance in the metabolism of fluvoxamine.

Prevalence of diabetes and impaired glucose tolerance in patients treated with clozapine compared with patients treated with conventional depot neuroleptic medications

BACKGROUND

Recent case reports suggest the association of the emergence of diabetes mellitus with clozapine treatment, although conventional neuroleptics have also been implicated. This study was conducted to determine if there is an increased risk of diabetes mellitus and/or impaired glucose tolerance (IGT) during clozapine treatment compared with treatment with conventional depot neuroleptics.

METHOD

In a district hospital in northern Sweden, blood glucose tests and, if necessary an oral glucose tolerance test were used to assess the prevalence of diabetes mellitus or IGT in 63 patients treated with clozapine compared with 67 patients treated with conventional depot neuroleptics (haloperidol, zuclopenthixol, fluphenazine, perphenazine, or flupenthixol). Diabetes mellitus and impaired glucose tolerance were classified according to World Health Organization criteria.

RESULTS

There were 3 dropouts in the clozapine group and 4 in the control group. Of subjects treated with clozapine, 12% (7/60) had type 2 diabetes mellitus, and 10% (6/60) had IGT. Of subjects treated with depot injections of neuroleptics, 6% (4/63) had type 2 diabetes mellitus and 3% (2/63) had IGT. None in either group had type 1 diabetes mellitus. Subjects in the clozapine group were significantly (p < .001) younger than subjects in the control group, whereas the 2 groups did not differ with respect to body weight, body mass index, or prevalence of diabetes mellitus in first-degree relatives.

CONCLUSION

Subjects treated with clozapine were more often classified as having type 2 diabetes mellitus or IGT compared with subjects in the control group. This difference did not, however, achieve statistical significance (p=.06).

Non-linear fluvoxamine disposition

AIMS

To study the pharmacokinetics of fluvoxamine when given in increasing doses to healthy volunteers.

METHODS

Ten healthy, non-smoking men were given maintenance treatment with fluvoxamine for 4 weeks. Eight subjects were CYP2D6 extensive metabolisers (EMs) and two were CYP2D6 poor metabolisers (PMs). As a measure of the CYP1A2 phenotype, the paraxanthine/caffeine ratio in saliva after intake of caffeine was studied. The fluvoxamine doses given were 25 mg day(-1) the first week, 50 mg day(-1) the second week, 100 mg day(-1) the third week and 200 mg day(-1) the fourth week, divided in two daily doses. On the seventh day every week, serum concentrations of fluvoxamine were followed for a dose interval of 12 h. After discontinuation of treatment, fluvoxamine concentrations were followed for 1 week.

RESULTS

For each of the three two-fold increases in given dose, the mean AUC increased 3.25-fold, 3.17-fold and 3.14-fold, respectively (P < 0.0001), indicating a decrease in oral clearance with increasing dose. The elimination half-life based upon the serum concentrations 12-48 h after discontinuation of fluvoxamine was 32.1 +/- 11.0 h whereas the half-life based upon the concentrations 3-7 days after discontinuation was significantly shorter, 15.8 +/- 4.2h (means +/- s.d.; P < 0.001). There were no significant correlations between the CYP1A2 phenotype and fluvoxamine AUCs at different doses (r = -0.56; P = 0.095 for the correlation between the paraxanthine/caffeine ratio in saliva and fluvoxamine AUC at a dose of 50 mg day[-1]). The two CYP2D6 PMs had AUC values in the same range as the EMs.

CONCLUSIONS

The present study conclusively demonstrates that fluvoxamine exhibits non-linear kinetics within the therapeutic dose interval. The reason for non-linearity is not Michaelis-Menten saturation kinetics of a single metabolic pathway, but rather a complex involvement of multiple parallel pathways.

Relationship between fluvoxamine pharmacokinetics and CYP2D6/CYP2C19 phenotype polymorphisms

OBJECTIVE

The purpose of this study was to investigate whether the disposition of fluvoxamine is associated with the CYP2D6 and CYP2C19 phenotype polymorphisms.

METHODS

The serum concentration of fluvoxamine was followed for 48 h after oral administration of a single dose of 50 mg fluvoxamine to five poor metabolizers of the CYP2D6 test drug dextromethorphan, five poor metabolizers of the CYP2C19 test drug mephenytoin, and five extensive metabolizers of both test drugs.

RESULTS

Poor metabolizers of dextromethorphan had significantly higher areas under the serum concentration-time curve than extensive metabolizers of dextromethorphan (mean 1.31 vs 1.00 mumol.h.l-1). There were no differences between poor and extensive metabolizers of mephenytoin (mean, 1.00 vs 1.15 mumol.h.l-1).

CONCLUSION

The results are consistent with a possible minor to moderate role of CYP2D6, but not CYP2C19, in fluvoxamine metabolism.

Fast titration experiments using heat conduction microcalorimeters

Thermopile heat conduction calorimeters normally have high time constants. Multistep titration experiments involving fast processes may then require several hours to perform. It is demonstrated that such experiments can be conducted about 10 times faster, without loss of accuracy, by use of a "dynamic correction method". For a new small vessel thermopile conduction calorimeter, injections can be made at 1.5-min intervals.

Enprostil and cimetidine: comparative efficacy and safety in patients with duodenal ulcer

The safety and efficacy of enprostil, 35 micrograms twice daily, and of cimetidine, 400 mg twice daily, in the treatment of duodenal ulcers were compared in a randomized, double-blind, parallel, multiclinic study. Endoscopy was performed before treatment and at 2-week intervals for 6 weeks or until the ulcer healed. Patients recorded their drug compliance, antacid use, ulcer symptoms, and adverse experiences daily. One hundred and six patients entered the trial, of which 104 were eligible for the initial endoscopy analysis. Base-line characteristics were similar in the two treatment groups. The cumulative healing rates in the enprostil group were 56%, 86%, and 92% at 2, 4, and 6 weeks, respectively, and those in the cimetidine group were 53%, 84%, and 90% (NS). The healing rates for nonsmokers at 6 weeks were 96% in the enprostil group and 97% in the cimetidine group, which were significantly greater than those for smokers--88% and 81%, respectively. There were no significant differences in the duration, severity, or frequency of daytime or nighttime pain between the groups. Seventeen of the enprostil patients (32%) reported 21 adverse experiences during the trial, and 20 of the cimetidine patients (39%) reported 23 adverse experiences. No patients withdrew because of adverse experiences. The two drugs were similarly safe and effective in the treatment of duodenal ulcer.