Drug management of antidiuretic hormone imbalance following pituitary surgery

ADH imbalance may occur in patients after pituitary surgery. Two cases are presented that demonstrate the problems associated with the disturbance of water metabolism. The medical management of these patients is discussed, with emphasis on the importance of the correct choice of pharmacological agents to control the manifestations of ADH imbalance.

Residual beta-cell function in type II diabetes and evaluation of the hepatic insulin extraction

Insulin and C-peptide (free insulin and C-peptide in insulin-treated patients) were measured after glucose stimulation in nine Type II diabetics on chlorpropamide, eleven insulin-treated maturity-onset diabetics and in 8 normal controls. Dissociation between C-peptide and insulin response to glucose was observed in several diabetics. The relation between incremental molar areas under C-peptide and insulin curves, after glucose challenge (delta CPR - delta IRI/delta CPR) were used to evaluate the hepatic insulin extraction in all but the insulin-treated diabetics. The lower insulin requirements and better control of the short-duration insulin-treated maturity-onset diabetics in relation to the long-term ones could not be explained either by the residual insulin secretion or by the level of "insulin antibodies". The chlorpropamide-responsive patients presented higher insulin levels after the glucose challenge and a lower hepatic insulin extraction than the non-responsive ones.

Epidemiological study of prevalence of chlorpropamide alcohol flushing in insulin dependent diabetics, non-insulin dependent diabetics, and non-diabetics

An epidemiological study was carried out to compare the prevalence of facial flushing in non-diabetics, patients with insulin dependent diabetes, and patients with non-insulin dependent diabetes in response to 40 ml sherry taken 12 hours after 250 mg chlorpropamide or placebo, administered double blind in randomised order. A flush after chlorpropamide but not placebo was reported by 6.2% of non-diabetics (17/273), 9.7% of insulin-dependent diabetics (14/145), and 10.5% of non-insulin dependent diabetics (25/239), excluding those receiving long term chlorpropamide treatment. The differences were not significant. This response was unrelated to age, sex, body mass index, and family history of diabetes in all three groups. Patients taking long term chlorpropamide, however, showed a significantly (p less than 0.01) higher prevalence of flushing after both chlorpropamide and placebo (56.3%; 9/16) compared with the rest of the non-insulin dependent diabetics (16.7%; 40/239), the insulin dependent diabetics (6.9%; 10/145), and the non-diabetics (5.9%; 16/273). Patients receiving long term chlorpropamide would be expected to flush with sherry after a placebo tablet because of therapeutic plasma concentrations of the drug. It is concluded that there is no evidence of an increased prevalence of chlorpropamide alcohol flushing in response to the single challenge test in non-insulin dependent diabetics compared with insulin dependent diabetics and non-diabetics except in selected patients taking chlorpropamide long term. This study does not support the hypothesis that the chlorpropamide alcohol flush is a specific marker for a subtype of non-insulin dependent diabetes.

Chlorpropamide-induced hyponatremia: incidence and risk factors

The incidence and risk factors of chlorpropamide-induced hyponatremia were assessed in diabetic outpatients. In 176 chlorpropamide-treated patients, 11 (6.3%) exhibited hyponatremia (serum sodium less than or equal to 129 meq/L) during the mean follow-up period of 7.4 yr. In contrast, only one (0.6%) developed hyponatremia in 162 tolbutamide- or glibenclamide-treated patients (P less than 0.005). Moreover, administration to elderly patients and combination with thiazide diuretics were regarded as significantly potent risk factors for the development of hyponatremia in patients receiving chlorpropamide.

Idiopathic neurogenic diabetes insipidus in a cat

A 5-year-old, domestic long-haired cat was presented for examination because of polydipsia, polyuria and inappropriate urination of 3 months' duration. Neurogenic diabetes insipidus was diagnosed, based on hyposthenuria with failure to concentrate urine in response to water deprivation and positive response to antidiuretic hormone administration. Treatment with hydrochlorothiazide or chlorpropamide orally gave inadequate antidiuresis, but response to injections of vasopressin tannate in oil was sufficient for satisfactory management.

The chlorpropamide alcohol flush test in diabetes mellitus: methods for objective evaluation

In order to study the objective value of the chlorpropamide alcohol flush (CPAF) the facial skin temperature and plasma acetaldehyde methods were compared to the visible response (flush/no flush) on standardized CPAF and alcohol challenge tests in 137 type 2 diabetics. Three criteria of CPAF are defined. A visible facial flush was noted in 53% of the diabetics. An increase in facial skin temperature of at least 1.0 degrees C was found in 90% of the subjects with a visible facial flush (flushers), but in only 14% of non-flushers. An increase in plasma acetaldehyde of at least 4 mumol/l was found in 86% of the flushers and in only 15% of non-flushers. Using these criteria to study CPAF all flushers satisfied at least two and 78% fulfilled all three criteria, while no non-flusher fulfilled more than one and 74% satisfied no CPAF criteria. However, with the alcohol test 5% could be identified as alcohol flushers having a falsely positive CPAF-test. In conclusion, it was possible to evaluate the CPAF test objectively with the facial skin temperature and plasma acetaldehyde methods.

The effect of chlorpropamide hyponatremia on mental status in a nursing home population

Fifty-nine nursing home patients (average age, 79.9 +/- .9 years) receiving chlorpropamide were screened with a serum sodium determination. Nine patients (15.3 percent) had a serum sodium concentration less than 135 mEq/L; six of these patients (10.2 percent) had a serum sodium equal to or less than 130 mEq/L; none of the patients had a serum sodium less than 125 mEq/L. Five hyponatremic patients (Na less than or equal to 130 mEq/L) and nine normonatremic patients (Na greater than or equal to 135 mEq/L) were screened with a standardized mental status examination and additional laboratory studies. The hyponatremic patients were switched to tolazamide after a one-week wash-out period, and the mental status examination and laboratory studies were repeated in both groups four weeks later. One patient in the hyponatremic group died during the course of the study; the other four became normonatremic on tolazamide. Mental status scores increased significantly in the hyponatremic group, 16.0 +/- 3.6 to 20 +/- 4.6 (a 37.3 +/- 21.5 percent increase), compared with the normonatremic group, 14.5 +/- 2.6 to 15.8 +/- 2.9 (a 7.8 +/- 3.2 percent increase). There were no significant differences in serum glucose, creatinine, chlorpropamide, or antidiuretic hormone concentrations between the two groups. It is recommended that periodic serum sodium determinations be obtained in geriatric patients receiving chlorpropamide.

Chlorpropamide-alcohol flushing and plasma chlorpropamide concentrations in diabetic patients on maintenance chlorpropamide therapy

Forty-three diabetic patients on maintenance chlorpropamide (100-750 mg daily) drank 0.2 ml/kg 90% ethanol after equilibration in a room controlled at 20 degrees C. Twenty-five patients had already noted marked alcohol flushing since starting chlorpropamide therapy (group A), while 13 had not observed this (group B). The remainder were teetotal or unsure of their reaction. Cheek temperature rise correlated with plasma chlorpropamide concentration (r = 0.6, p less than 0.001) in all patients and was inversely related to basal cheek temperature (r = -0.35, p less than 0.02). Plasma chlorpropamide correlated with daily chlorpropamide dose (r = 0.8, p less than 0.001) but not with basal cheek temperature. The correlation between chlorpropamide level and cheek temperature rise was strengthened on analysis of group A alone (r = 0.7, p less than 0.001) and absent in group B (r = 0.2, p greater than 0.3) who tended to have lower chlorpropamide levels and cheek temperature rise than group A.

Metabolic studies in chlorpropamide-alcohol flush positive and negative Type 2 (non-insulin dependent) diabetic patients with and without retinopathy

Serum insulin and blood metabolite responses to oral glucose with and without intravenous naloxone were measured in 24 chlorpropamide-alcohol flush positive and negative Type 2 (non-insulin dependent) diabetic patients with and without retinopathy. In the chlorpropamide-alcohol flush positive patients with retinopathy, fasting blood glucose was increased greater than 40% and the serum triglycerides were increased over twofold compared with each of the other three groups. Following oral glucose (50 g), the chlorpropamide-alcohol flush positive diabetic patients with complications had a lower serum insulin and higher blood glycerol than the other three groups. Thus, chlorpropamide-alcohol flush positive subjects with retinopathy showed distinct metabolic differences from the other three groups. There was no evidence that opiate-receptors influenced the metabolic response to oral glucose in the Type 2 diabetic patients since the infusion of intravenous naloxone produced no effect on the serum insulin or blood metabolites.

High density lipoprotein cholesterol and apolipoprotein a-1 concentrations in non-insulin dependent diabetics treated by diet and chlorpropamide

Fasting serum concentrations of high density lipoprotein cholesterol (HDLC) and apolipoprotein A-I (apo A-I) were determined in non-insulin dependent diabetes at diagnosis, diabetics treated by diet alone, diabetics treated by diet plus chlorpropamide, and normal controls matched for sex, age and body weight. Serum concentrations of HDLC and apo A-I were decreased in all groups of diabetics. There were no significant differences in HDLC and apo A-I concentrations between the diabetics at diagnosis and those treated by diet alone or diet plus chlorpropamide. Neither HDLC nor apo A-I concentrations were correlated with glucose concentrations. The results indicate that serum concentrations of HDLC and apo A-I are reduced in non-insulin dependent diabetics at diagnosis, and are not significantly affected by chronic diet and chlorpropamide therapy.

Chronic chlorpropamide therapy of noninsulin-dependent diabetes augments basal and stimulated insulin secretion by increasing islet sensitivity to glucose

To determine the effect of chronic sulfonylurea therapy on islet function in noninsulin-dependent diabetes mellitus (NIDDM), studies were performed in 18 untreated NIDDM patients before and after 12-16 weeks of chlorpropamide therapy. Fasting plasma glucose (FPG) fell with chlorpropamide therapy from 249 +/- 16 to 157 +/- 8 mg/dl (mean +/- SEM; P less than 0.001), and basal insulin increased from 17 +/- 2 to 24 +/- 3 microU/ml (P less than 0.001). The percent change in basal insulin correlated with the pretreatment FPG (r = 0.62; P less than 0.01) and inversely with the change in FPG during chlorpropamide (r = -0.57; P less than 0.025). Thus, patients with the highest pretreatment FPG showed the largest relative increase in basal insulin and the largest fall of FPG with chlorpropamide therapy. In nine patients, arginine-stimulated acute insulin responses (AIR) were studied at each of three plasma glucose (PG) levels both before and during chlorpropamide treatment. AIR at FPG was not different before and during treatment. However, when PG during treatment was matched by glucose infusion to the pretreatment FPG, the AIR was clearly increased during chlorpropamide therapy (176 +/- 65 vs. 49 +/- 11 microU/ml; P less than 0.02). When AIR is plotted against PG for each individual, the slope of the regression line generated (slope of glucose potentiation) is a measure of that patient's islet sensitivity to glucose. The logarithm of the slope of glucose potentiation correlated inversely with FPG (r = -0.92; P less than 0.001). Chlorpropamide treatment increased the slopes of potentiation from 0.26 +/- 0.11 to 1.47 +/- 0.70 (P less than 0.01). We conclude that chronic chlorpropamide therapy augments both basal and stimulated insulin secretion in NIDDM and that this may be an important mechanism of the drug's hypoglycemic effect. The data support the hypothesis that the hyperglycemia of NIDDM is related to islet insensitivity to glucose and that chlorpropamide treatment improves this impairment.

Chlorpropamide and glibenclamide serum concentrations in hospitalized patients

The relationships between the daily doses of the drugs and the steady state serum concentration was studied in 51 patients on chlorpropamide and in 27 patients on glibenclamide. All the patients were hospitalized during the study. A wide interindividual variation in chlorpropamide levels was observed and thus, the prediction of drug concentration was difficult from the dosage alone, despite a statistically significant correlation between the dose per body weight and the serum drug level. The differences could not be explained on the serum creatinine levels, age, sex, liver diseases or other drugs used concomitantly. In the case of glibenclamide, a wide interindividual variation in serum concentration of the drug also occurred.

The effect of chronic sulfonylurea therapy on hepatic glucose production in non-insulin-dependent diabetes

In 20 patients with untreated non-insulin-dependent diabetes mellitus (NIDDM), there was a positive relationship between fasting plasma glucose (FPG) and glucose production rate, calculated by the isotope dilution technique (r = 0.72, P less than 0.001). This suggests that glucose production rate is an important determinant of FPG in untreated NIDDM. Fifteen patients were also studied during therapy with chlorpropamide for 3-6 mo. During therapy, FPG was lower (133 +/- 9 vs. 216 +/- 20 mg/dl, mean +/- SEM; P less than 0.001), glucose production was lower (59.5 +/- 2.0 vs 77.6 +/- 4.9 mg/m2/min; P less than 0.005), and there was a significant correlation between the fall in glucose production and the fall in FPG (r = 0.59, P less than 0.05). Fasting IRI levels increased in some, but not all, patients during chlorpropamide (untreated 18 +/- 2, treated 21 +/- 2 muU/ml; P= NS). However, there was a significant relationship between the percent rise in IRI and the fall in glucose production during treatment (r = 0.75, P less than 0.001). Patients with a rise in fasting insulin during therapy had a greater fall in glucose production than those whose insulin did not rise (25.4 +/- 8.1 vs. 7.8 +/- 2.4 mg/m2/min; P less than 0.005). When a low-dose insulin infusion was given to approximate the increases of portal venous insulin during therapy, similar falls of glucose production occurred. We conclude that inhibition of endogenous glucose production during chronic chlorpropamide therapy is an important mechanism for the lowering of FPG and that enhanced insulin secretion is the reason for the major part of this inhibition. The small fall in glucose production in those patients whose insulin level did not rise during therapy suggests an additional contribution by some other mechanism.

Glycosylated hemoglobin and its temporal relationship to plasma glucose in non-insulin dependent (type 2) diabetes mellitus

Total glycosylated hemoglobin (HbAI) and random plasma glucose were measured at monthly intervals for 6 mo in 33 non-insulin dependent (type 2) diabetics. The mean HbAI and mean plasma glucose in individual patients over the 6 mo showed a close correlation (p less than 0.001). A significantly higher HbAI (p less than 0.001) for a given plasma glucose was seen in those patients receiving combined chlorpropamide and metformin therapy (n = 14) than in those receiving chlorpropamide alone (n = 19). For each patient correlation coefficients were calculated between plasma glucose and HbAI with time lags of 0.1 and 2 mo. The coefficients with no time lag showed a significant tendency to be positive (p less than 0.01) whereas those with time lags of 1 or 2 mo were not significant. A constant proportional variability of both HbAI and plasma glucose over time was demonstrated, the mean coefficient of variation for HbAI being 8.4 +/- 2.7% and for plasma glucose 22.3 +/- 9.7%. We conclude that HbAI provides an index of plasma glucose control, not during the preceding few months as was previously thought but, during the previous few weeks. In terms of variability from month to month a single HbAI determination was equivalent to approximately the mean of 3 single plasma glucose values.

Islet changes induced by hyperglycemia in rats. Effect of insulin or chlorpropamide therapy

To investigate the effect of hyperglycemia on normal islets, rats were made diabetic by a 95% partial pancreatectomy and treated with insulin, saline, or chlorpropamide for 3 mo. Histologic examination and morphometry of the residual pancreas showed islet enlargement and fibrosis that correlated with the mean lasting plasma glucose during the experimental period. Treatment of diabetes with insulin prevented the islet disorganization. The B-cell area per islet remained constant and was not affected by hyperglycemia. Chlorpropamide had little effect on the fasting plasma glucose or islet structure, and no "beta cytotrophic" effect was seen. Chronic hyperglycemia induces islet damage that may affect residual B-cell function in diabetes.

Alcohol in asthma and the bronchoconstrictor effect of chlorpropamide

The effect of drinking 40 ml of sherry on peak expiratory flow rate in 16 normal subjects and 19 patients with asthma was assessed after oral administration of either chlorpropamide or placebo. After placebo and sherry normal subjects showed no change in peak expiratory flow rate, while an increase was usually shown by patients with asthma. This bronchodilation was more marked in patients whose base-line peak flow rate was less than 50% predicted. Ingestion of chlorpropamide before sherry significantly modified the bronchodilating properties of sherry; five of the 19 patients with asthma showed airway narrowing on 11 of 19 occasions tested. Further studies in one patient suggest that this bronchoconstriction may be mediated by congeners in sherry rather than ethanol. These findings confirm the observation that chlorpropamide and sherry can cause airway narrowing in patients with asthma but shows that this response is not always reproducible. The bronchodilator effect of alcohol in patients with asthma may have therapeutic implications.

Impaired effect of sulfonylurea following increased dosage

Ten Type 2 diabetics were examined during long-term treatment, at two dosage levels, with chlorpropamide once daily and glipizide t.i.d. Drug concentrations were measured by gas chromatography and high-pressure liquid chromatography, respectively, plasma insulin (IRI) by radio-immunoassay, and blood glucose enzymatically. Both drugs gave continuous sulfonylurea exposure, even at the lower dosage, and the mean plasma concentrations were almost doubled after the increase in dose. Neither the IRI nor the glucose response to meals showed any therapeutic improvement following the increase in chlorpropamide dosage. The lower dosage of glipizide produced better glucose utilization than chlorpropamide. On the other hand, the increased dose of glipizide led to impairment instead of further improvement. As this was associated with enhanced rather than reduced IRI levels, the impairment might have been due to increased peripheral insulin resistance. Thus, glipizide offers a therapeutic advantage over chlorpropamide, but its effectiveness may be restricted not only by limitations set by the disease, but also by counter-regulatory mechanisms that develop during continuous exposure to sulfonylureas at high levels.

Chlorpropamide alcohol flush and circulating met-enkephalin: a positive link

Chlorpropamide-alcohol flushing may be due to sensitivity to endogenous opiates. To investigate this possibility the plasma met-enkephalin and beta-endorphin responses to sherry with and without chlorpropamide were studied in six patients with non-insulin dependent diabetes and in six normal subjects. After chlorpropamide all patients showed a rise in met-enkephalin concentrations from a basal level of 50 +/- 7.2 ng/l to a peak of 75 +/- 8.1 ng/l (p less than 0.001). In contrast, before chlorpropamide treatment was started met-enkephalin values did not change after alcohol. No significant changes in beta-endorphin values were observed. In six normal subjects pretreated with chlorpropamide the met-enkephalin concentration also rose from a basal level of 72 +/- 15 ng/l to a peak of 103 +/- 9.4 ng/l (p less than 0.002). Again, the met-enkephalin rise was not observed after placebo. Neither beta-endorphin concentrations nor facial temperature changed significantly. These data suggest that endogenous opiates may be implicated in CPAF. Furthermore, this is the first study in which a significant change in circulating met-enkephalin values has occurred.