Clinical and electroencephalographic assessment of diazepam in liver disease

Benzodiazepines and risk for hepatic encephalopathy in patients with cirrhosis and ascites

Background

There is limited evidence to support the belief that benzodiazepines increase cirrhosis patients' risk of hepatic encephalopathy (HE).

Objective

We aimed to examine the association between benzodiazepine use and HE development in cirrhosis patients.

Methods

We used data on 865 cirrhosis patients with ascites from three trials to study the effect of benzodiazepine use on development of first-time HE. For each patient, we classified periods of benzodiazepine use by the number of days since initiation. We used Cox regression to compare the risk of HE in current benzodiazepine users vs. non-users adjusting for confounders.

Results

Cirrhosis patients were not at increased risk of HE for the first two days of benzodiazepine use, but then faced a five-fold increased risk of HE during days 3 to 10 of benzodiazepine use. The risk of HE was not increased for those who had been using benzodiazepines for more than 28 days.

Conclusion

Cirrhosis patients who had begun using benzodiazepines between 3 and 10 days previously had a markedly increased risk of developing first-time HE. Cirrhosis patients who had been using benzodiazepines for just one or two days or continued use for more than 28 days did not have such an excess risk.

Effects of benzodiazepines on triphasic waves: implications for nonconvulsive status epilepticus

Nonconvulsive status epilepticus (NCSE) is often diagnosed based on abolition of rhythmic sharp waves by benzodiazepines. It is possible that sharp waves resulting from metabolic (nonepileptic) encephalopathies may also respond to benzodiazepines and are potentially misdiagnosed as NCSE. The authors hypothesized that triphasic waves (TW) resulting from metabolic encephalopathy are abolished by benzodiazepines. They retrospectively identified patients with TW resulting from metabolic encephalopathy who had EEG recordings before, during, and after benzodiazepine administration. Benzodiazepines were given either because of the possibility of NCSE or for a medically indicated purpose. All patients were diagnosed definitively with a metabolic cause of encephalopathy and not NCSE. Ten patients (mean age, 59 years) met the criteria and were reviewed. TW resolved persistently in four patients and intermittently in six patients. Background activity slowed in five patients and was attenuated in five patients. Unresponsive patients did not arouse and three of five drowsy patients became less responsive. Rhythmic sharp waves resulting from metabolic encephalopathy are abolished by benzodiazepines, similar to NCSE, but without improvement in mental status. This suggests that definitive electrographic diagnosis of primary NCSE should not be based entirely on abolition of sharp waves by benzodiazepines. This also implies that gamma-aminobutyric acid neurotransmission is important in the expression of TW.

Mechanism of the excessive sedative response of cirrhotics to benzodiazepines: model experiments with triazolam

Mechanisms responsible for disproportional sedation resulting from triazolam administration to patients with cirrhosis were investigated. Ordinary sedative doses (0.25 mg) were given p.o. to 8 cirrhotics and 18 controls. Plasma concentrations of unbound drug were assessed by capillary gas chromatography and equilibrium dialysis. Median apparent oral clearances of unbound triazolam were 14.8 ml per min per kg in cirrhotics and 23.9 ml per min per kg in controls (p less than 0.01). Clearances were significantly correlated with severity of liver disease as assessed by the aminopyrine breath test (Rs = 0.77, n = 17, p less than 0.001). At a time when plasma concentrations of unbound triazolam were the same in both groups, i.e., 2.25 hr after dosing, flicker sensitivity at 5 Hz which was used as an index of CNS performance was impaired by a factor of 3.2 in cirrhotics and 1.4 in controls (p less than 0.01 for group difference). Performance was also significantly lower in cirrhotics with the digit symbol substitution test (p less than 0.05). It is concluded that, in patients with cirrhosis, disproportional sedation after benzodiazepine administration may be due not only to impaired drug elimination, but also to hypersensitivity of the brain.

Fulminant hepatic failure

Fulminant hepatic failure is an uncommon but dramatic illness with a high mortality. Viral hepatitis or drug toxicity is the usual cause. In the severe forms of the illness the patients, often young and previously healthy, rapidly become profoundly unwell due to extensive hepatic necrosis. Coma is accompanied by a disastrous disturbance of all the synthetic, metabolic and excretory functions of the liver. Management is largely supportive and multisystem complications may demand all the resources of the intensive care unit to allow survival. Systems for temporary hepatic support have aroused interest, based on the assumption that the hepatic lesion is potentially reversible. A number of heroic techniques have been tried and abandoned. Encouraging reports of charcoal column haemoperfusion have yet to be confirmed by controlled clinical trial.

Drug prescribing in hepatobiliary disease

Liver disease in man is associated with a variety of pathophysiological processes which may influence the disposition of drugs in several ways. Interpretation of the observed pharmacokinetic changes in liver disease requires an understanding of the relationship between systemic drug clearance (Cls), volume of distribution (Vd) and the elimination half-life [t1/2(beta)], i.e. t1/2(beta) = 0.693 . Vd/Cls. Half-life will be a measure of the fluctuation in drug level one may expect with continued administration of a drug while clearance will determine the dose required to achieve a particular steady state level. Liver disease may affect clearance and volume of distribution and so produce changes in half-life; in addition, alterations in plasma binding of drugs may occur and so influence free (unbound) drug levels. It is also possible that the end organ response, particularly in the case of sedative drugs, may be affected by liver disease. Other factors such as age, nutrition, smoking, and concomitant drug therapy may also influence drug elimination in patients with liver disease. At the present time, caution should be exercised in prescribing drugs to patients with liver disease and the dose should be titrated to the clinical response. The development of liver 'function' tests using model or marker drugs may offer some help to the prescriber in the future and enable a less empirical approach.

Intravenous administration of diazepam in patients with chronic liver disease

The EEG response and drug kinetics after intravenous infusion of diazepam at 1-0 mg/min until nystagmus, dysarthria, and moderate sedation developed, has been investigated in five normal subjects and 17 patients with chronic liver disease. Diazepam induced adequate premedication with a similar clinical response in all subjects with no adverse reactions. Maximal response was during or within five minutes of infusion. The dose of diazepam required in liver chronic disease was 17-9 +/- 1-4 mg (M +/- SEM) compared with 27 +/- 5-4 mg in controls (p less than 0-01). Dose correlated significantly with serum albumin (p less than 0-05). Baseline mean dominant frequency (MDF) and slow wave index (SWI) significantly correlated with albumin (p less than 0-01). After diazepam, the MDF decreased and SWI increased. The change was greatest at the time of maximal clinical response. It was greater in liverdisease and was greatest in patients with previous hepaticencephalopathy. In spite of reduced dose requirements in liver disease, there was no significant difference in plasma concentration at the end of drug infusion...

Pharmacokinetics of diazepam in disordered liver function

The plasma elimination curves of diazepam following intravenous administration of 10 mg were studied in nine patients with cirrhosis of the liver and four patients without liver disease. The data were analyzed according to a two compartment model. The mean biological half-life (T/2) of diazepam was increased five-fold in patients with cirrhosis compared to the controls (164 hours vs. 32.1 hours). The plasma clearance of diazepam could be correlated neither with a quantitative measure of liver function, as estimated by galactose elimination capacity, nor to semiquantitative measures of liver function, such as serum albumin and prothrombin. It is suggested that the plasma clearance of diazepam is an inaccurate index of its rate of hepatic metabolism due to the complex kinetics of the drug.

The effects of age and liver disease on the disposition and elimination of diazepam in adult man

This study investigates the separate effects of age and hepatocellular liver disease on the disposition and elimination of diazepam (Valium) in man. The drug was given either by rapid intravenous injection (0.1 mg/kg) or orally (10 mg) to 33 normal volunteers rnaging in age from 15 to 82 yr as well as to 9 individuals with alcoholic cirrhosis, 8 with acute viral hepatitis, and 4 with chronic active hepatitis. In the normal individuals, the terminal plasma half-life of diazepam, (t 1/2 (B)) exhibited a striking age-dependence; at 20 yr the t 1/2 (beta) was about 20 h, but it increased linearly with age to about 90 h at 80 yr. The plasma clearance of diazepam in the majority of the normal subjects was between 20 and 32 ml/min and showed no significant age-dependence. Cigarette smoking did not affect the half-life or the clearance. Additionally, neither the plasma binding (97.4 plus or minus 1.2%, mean plus or minus SD) nor the blood/plasma concentration ratio (0.58 plus or minus 0.16) of diazepam showed any age-related changes (P greater than 0.05). By contrast, analysis of the intravenous data according to a two-compartment open model indicated that both the initial distribution space (V1) and the volume of distribution at steady state [Vd(ss)] of diazepam increased linearly with age (P less than 0.005). The increase in Vd(ss) was secondary to the change in V1. It appears then that the prolongation of t 1/2 (beta) of diazepam with age is primarily dependent on an increase in the initial distribution volume of the drug. The plasma concentration/time course of the metabolite, desmethyldiazepam, was also affected by age. In older individuals, the initial presence and the peak values of desmethyldiazepam were observed later and the metabolite was present in lower concentrations. Despite the profound prolongation of t 1/2 (theta) with age, the constancy of diazepam clearance indicates that drug plasma concentrations will not accumulate any more in the old than the young, and chronic dosage more in the old than the young, and chronic dosage modifications based on pharmacokinetic considerations are unnecessary. Data obtained in patients with liver disease were compared with those found in age-matched control groups. Patients with cirrhosis showed a more than twofold prolongation in the half-life of diazepam (105.6 plus or minus 15.2 vs. 46.6 plus or minus 14.2 h, P less than 0.001).

Psychotropic drugs in somatic disorders

Current trends in the employment of psychotropic medication in somatic illness are considered, and some of the theoretical issues raised by this practice are explored. While much further clinical investigation is needed, a review is made of currently available knowledge regarding psychopharmacotherapy in specific clinical settings: pain, delirium, ischemic heart disease, gastrointestinal disorders, dermatological illness, and in renal, hepatic and pulmonary insufficiency.