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At least 19 recordsLinked to original sources
PubMed1977

Serum phenformin concentrations in patients with phenformin-associated lactic acidosis.

Phenformin concentrations were measured in serum from seven patients with phenformin-associated lactic acidosis, and initial values ranging from 20 to 625 ng./ml. were obtained. Five of the seven patients had serum concentrations within the usual therapeutic range of up to 241 ng./ml. Serum phenformin concentrations were measured serially, and apparent half-lives of 5, 25, and 30 hours were obtained in three patients with serum creatinine concentrations of 1.7, 7.6, and 6.0 mg./dl., respectively. Although the half-life of phenformin was prolonged in azotemic patients, no correlation between serum creatinine concentration and serum phenformin could be demonstrated; furthermore, the severity of lactic acidosis as measured by arterial pH and lactate concentration did not correlate with the serum creatinine concentration.

Aged↗
PubMed1977

The absorption of phenformin and its effects on glucose and water absorption in isolated perfused rat small intestine.

The effects of phenformin on glucose and water absorption from isolated perfused rat small intestine were studied. Luminal phenformin inhibited glocose and water absorption progressively as its concentration was increased from 0-1-1-0 mg.ml-1. At 0-5 mg phenformin ml-1, inhibition increased with time of exposure to phenformin up to 15 min and thereafter remained constant. Arterial infusion of phenformin (1-0 mg-ml-1) produced less inhibition of glucose and water absorption. The site of phenformin's action appeared to be intracellular. Phenformin absorption from a luminal perfusate (0-5 mg-ml-1) was measured. Although it was rapidly absorbed (22 microgram.cm intestine-1.h-1) from the lumen, less than 2 microgram.cm-1.h-1 appeared at the serosal surface of the intestine. In subsequent phenformin-free perfusion, only 25% of the absorbed phenformin was recovered in the luminal and serosal effluents.

Animals↗
PubMed1978

Epidemiology of adverse drug reactions to phenformin and metformin.

Adverse drug reactions (ADRs) to phenformin and metformin reported to the Swedish Adverse Drug Reaction Committee during 1965--77 were analysed in relation to sales and prescription data. The biguanides accounted for 0.6% of all reported adverse drug reactions but for 6% of the fatal cases (all phenformin). Sixty-four ADRs to phenformin and eight to metformin were classified as causal relation "probable" or "not excluded." Fifty-one of these reactions (71%) were lactic acidosis, all but one being reactions to phenformin. After 1973 phenformin was prescribed less in Sweden and metformin became predominant. A nationwide prescription survey during 1975--6 disclosed no differences in age and sex between patients receiving phenformin and metformin. The mean daily doses prescribed in 1976 were 74 mg of phenformin and 1.5 g of metformin. The numbers of ADRs to the two drugs reported during 1975--7 were related to use. The relative incidences of ADRs reported for phenformin and metformin did not differ. Significantly more cases of lactic acidosis and deaths were reported for phenformin.

Acidosis↗
PubMedDate not supplied

Do metformin and phenformin potentiate differently B-cell response to high glucose? An in vitro study on isolated rat pancreas.

The study investigated the effects of metformin and phenformin, at "therapeutic" concentrations, on the pancreatic A-, B- and D- cell response to glucose using the isolated perfused rat pancreas model. Changes in the rate of pancreatic lactate output after these biguanides were also evaluated. Metformin--at 1.5 micrograms/ml--and phenformin--at 100 ng/ml--were separately infused both at 160 mg/dl and 300 mg/dl glucose levels. Neither metformin nor phenformin affected glucagon or somatostatin secretion during these two metabolic stimuli with glucose, nor did they significantly influence insulin response to the lower glucose stimulus. Both metformin and phenformin enhanced insulin response to 300 mg/dl glucose infusion and increased the second phase of the B-cell secretory profile but only phenformin significantly enhanced the pancreatic lactate output rate during the 300 mg/dl glucose infusion. Infusion with dichloroacetate (a stimulator of the mitochondrial pyruvate oxidation) or with verapamil (a calcium antagonist) alone did not modify the insulin response to high glucose concentrations. During metformin infusion dichloroacetate neither modified metformin's effects on B-cell response to high glucose nor did it affect the pancreatic lactate output rate. On the other hand dichloroacetate opposed phenformin's effects on the B-cell response to high glucose and reversed the rise in the pancreatic lactate output rate. Verapamil inhibited the effect of metformin on the B-cell response to high glucose but failed to affect phenformin's influence on high-glucose induced insulin release. These data suggest both metformin and phenformin potentiate--at least in rats--the late phase of insulin secretory response to high glucose. However metformin seems to influence pancreatic B-cell activity mainly by facilitating the trans-membrane calcium ion influx responsible for the second phase of insulin release. Phenformin's influence seems indirect since it increases pancreatic lactate production which mediates the enhanced B-cell response to glucose.

Animals↗
PubMed1989

The hyperlactatemic effect of biguanides: a comparison between phenformin and metformin during a 6-month treatment.

To compare the chronic hyperlactatemic effect of phenformin and metformin, we performed a double-blind study in 10 non insulin-dependent diabetics without any other known hyperlactatemic condition. After a pre-study period, each patient was allocated to a 6-month treatment with phenformin (50 mg bid) or metformin (850 mg bid) in random sequence. Body weight values were not significantly different between phenformin and metformin. Diabetic control was significantly (p less than 0.001) improved by both biguanides versus pre-study, but was the same during metformin and phenformin: HbAI = 13.8 +/- 0.3 SEM% during pre-study 9.7 +/- 0.2% during phenformin, 10.2 +/- 0.2% during metformin. Mean values of plasma lactate during metformin were significantly lower versus phenformin (1.30 +/- 0.05 vs 1.64 +/- 0.05 mmol/l, p less than 0.001). Mean values of plasma lactate/pyruvate ratio during metformin were significantly lower versus phenformin (16.92 +/- 0.59 vs 22.65 +/- 0.87, p less than 0.001), but not versus pre-study (16.19 +/- 0.51). These results indicate that: 1) during a 6-month treatment with a diabetic control of similar degree phenformin produces a significantly higher hyperlactatemic effect vs metformin; 2) metformin treatment is associated with less impairment of intracellular redox state versus phenformin, and therefore should be considered advantageous in the long-term treatment of non insulin-dependent diabetics.

Acidosis, Lactic↗
PubMed1975

The effect of phenformin-HCl on patients with diabetes mellitus, studied under strict balance conditions.

Under strict balance conditions we studied the effect of phenformin in 5 patients with diabetes mellitus. In all cases phenformin lowered the blood glucose values, and all patients showed a reduction of glycosuria. Contrary to other reports body weight increased during phenformin treatment. This was accompanied by positive nitrogen, phosphorus and calcium balances. The weight gain can be explained by the positive caloric balance, mainly caused by the diminished glycosuria. No change in B.M.R. or R.Q. was seen. During phenformin treatment there was a drop in cholesterol and total lipid levels in 4 patients. No conclusions could be drawn about the effect of phenformin on triglycerides, phospholipids and lipoprotein spectra. Phenformin treatment did not affect the disappearance of glucose, nor the insulin levels after intravenous glucose loading. During oral glucose loading phenformin caused a significant fall in blood glucose levels, accompanied by an increased insulin response in one patient. In the other 4 patients phenformin had no effect on either parameter.

Aged↗
PubMed1977

Plasma glucagon suppression by phenformin in man.

In an attempt to elucidate the mechanism of action of phenformin, eleven juvenile-onset, insulin-requiring diabetic subjects underwent four different treatment regimens during standard breakfast tests. These four treatments were: control (no insulin or phenformin); insulin alone (15 U regular insulin administered subcutaneously one-half hour before breakfast); phenformin alone (50 mg of the timed-release capsule given twice daily for three days before the study and two and one-half hours before breakfast on the day of study); and phenformin plus insulin (in the amounts and at the times stated above). Phenformin was found to decrease postprandial hyperglycaemia significantly when compared with control values, and its addition to insulin further decreased the postprandial glucose rise below that found with insulin alone (p less than 0.005). These effects were associated with a reduction in early (30-min) postprandial hyperglucagonaemia (p less than 0.05). Triglyceride levels, gastrin secretion, growth hormone levels, and increments of alpha-amino nitrogen were not affected by phenformin. Thls, suppression of postprandial hyperglucagonaemia may be an additional mechanism in the reduction of postprandial hyperglycaemia after phenformin.

Adult↗
PubMed1977

[Treatment of primary hyperlipoproteinemia type IIb and IV. Comparison of the lipid lowering effect of phenformin, clofibrate, and a combination of both (author's transl)].

22 outpatients with primary hyperlipoproteinemia type IIb and IV were treated in periods of eight weeks as follows: placebo; 0,15 g phenformin/day; 0,15 g phenformin + 1,5 g clofibrate/day; 1,5 g clofibrate/day; placebo. Compared to the first placeboperiode the serumtriglycerides were significantly lowered by phenformin (about 26%), by the combined treatment with phenformin + clofibrate (60%) and by clofibrate (51%) after eight weeks of treatment. The serumcholesterol was significantly lowered by phenformin (10%) and by the combined treatment with phenformin and clofibrate (14%), but not significantly by clofibrate (8%). After eight weeks of treatment with phenformin alone or in combination with clofibrate the body weight decreased significantly (1,9% or 1,4%). These changes in body weight were not related to changes in blood lipids. In conclusion, the combined treatment with 0,15 g clofibrate/day was more effective in lowering increased serum lipids than the treatment with phenformin or clofibrate alone.

Adult↗
PubMed1979

Metabolic effects of glucocorticoid and ethanol administration in phenformin- and metformin-treated obese diabetics.

Glucocorticoid administration for 24 hours to phenformin-treated obese diabetics increased blood lactate and lactate/pyruvate (L/P) ratio to higher levels than those found when only one drug was given. In one of 10 subjects, a metabolic acidosis with a blood lactate of 6.2 mmol developed during simultaneous administration of the two drugs. Diabetics treated with phenformin or metformin in equipotent dosages exhibited the highest blood lactate, L/P ratio, and beta-hydroxybutyrate levels during phenformin treatment, both before and during glucocorticoid administration. Ethanol administration to biguanide-treated diabetics resulted in identical increases in blood lactate and L/P ratio during phenformin and metformin treatment. These findings are consistent with the hypothesis that phenformin has a stronger inhibitory effect of gluconeogenesis than metformin. This may be one reason why lactic acidosis is seen much more often in phenformin- than metformin-treated patients.

Aged↗
PubMed1975

Phenformin-induced lactic acidosis in diabetic patients.

Eighteen diabetic patients with lactic acidosis (L.A.) were analyzed for possible causal factors, metabolic changes, and efficacy of treatment. An antecedent phenformin therapy was performed in fifteen cases and was associated with renal insufficiency in ten cases and liver disease in eight cases. Tissular anoxia of primary hemodynamic or respiratory origin was absent in all cases. The severe metabolic acidosis (pH m.93 +/- 0,03; HCO3-= 6 +/- 1 MM; PaCO2 = 18 +/- 2 MM. Hg) and hyperlactatemia (14.2 +/- 0.3 mM) were associated with high lactate/pyruvate ration (70 +/- 22). High alanine levels (up to 4.6 mM) were measured in some of these patients. High beta-hydroxybutrate levels were sometimes measured (up to 7.6 mM), and substantial amounts of acetoacetate were also detected in twelve cases. Glucagon level was always increased (1,050 +/- 240 pg./ml.), and insulin/glucagon ratio was low. Cortisol (49 +/- 10 mug./100 ml.) and HGH (10.8 +/- 0.6 ng./ml.) were also elevated. Increased plasma levels of phenformin were measured in five L.A. diabetic subjects (50 +/- 5 mug./ml.) by comparison with other phenformin-treated diabetic subjects. The specificity of the assay was investigated, and phenformin metabolites were characterized by thin-layer chromatography. Por the treatment of L.A., adjunction of dialysis and furosemide improved the efficacy of early and massive sodium bicarbonate infusion. It is suggested that accumulation of phenformin via renal insufficiency plays a determinant role in causing L.A. through an impairment of lactate metabolism in the liver. An accelerated epuration of the drug may be helpful in therapy of L.A. Phenformin treatment should be avoided in case of renal and/or liver insufficiency.

Adult↗
PubMedDate not supplied

Comparative study of the therapeutic effects of glibenclamide or the fixed combination of glibenclamide-phenformin with those of gliclazide or chlorpropamide.

This study was designed to compare the therapeutic effects of glibenclamide or the fixed combination of glibenclamide-phenformin with those of gliclazide, chlorpropamide or biguanides in non-insulin-dependent diabetes. It is divided into two parts: a) in the retrospective study (473 subjects), glucose control of patients who were transferred from chlorpropamide, gliclazide, glibenclamide, glibenclamide + biguanide or metformin to the fixed combination glibenclamide-phenformin in the same tablet (2.5 mg and 25 mg, respectively) was monitored. A statistically significant decrease of blood glucose and glycosylated hemoglobin values was found under the combination of glibenclamide-phenformin contained in the same tablet in contrast to the values obtained with the treatment with glibenclamide, gliclazide, chlorpropamide, combination of glibenclamide and biguanides, metformin, and insulin. b) In the prospective study (57 subjects), the patients were transferred from chlorpropamide or gliclazide to glibenclamide for 3 months and then reallocated to the previous treatment for 3 additional months. It was found that under glibenclamide, glucose control was significantly better than under chlorpropamide or gliclazide. In conclusion, glibenclamide, a second generation sulfonylurea, and the fixed combination glibenclamide-phenformin in the same tablet are more effective compared to the other antidiabetic agents here studied and lead to a better control of type II diabetic patients. There was no increase in plasma lactic acid concentration in all patients studied before and after having received the fixed combination of glibenclamide-phenformin in the single tablet form.

Blood Glucose↗
PubMed1976

Can phenformin-induced lactic acidosis be prevented?

Although patients taking phenformin are more likely to develop lactic acidosis in the presence of renal, cardiovascular, or hepatic disease, criteria for safe use of the drug are not well established. Eight diabetics died of lactic acidosis in Nottingham in 1972-5 and all were taking phenformin in therapeutic doses. Six had attended the diabetic clinic within a month of their terminal illness. Two patients had appreciable renal impairment and should not have been given phenformin. Four had hypertension and minimal evidence of renal disease, while in two no predisposing factor was identified. There are so many contraindications to the use of phenformin that it is doubtful whether patients on the drug can be monitored adequately. We suggest that phenformin should be withdrawn from general use.

Acidosis↗
PubMed1975

Lactic acidosis associated with phenformin therapy. Evidence that inhibited lactate oxidation is the causative factor.

Using uniformly labeled 14C L-lactate, we have studied the turnover and oxidation of lactic acid in a patient who presented with a mild lactic acidosis while on phenformin medication. As with other cases of lactic acidosis associated with phenformin therapy, this subject had impaired renal function as evidenced by serum creatinine levels of 2 mg./100 ml. and BUNs of 40 mg./100 ml. Comparison of the rate of lactate oxidation relative to the rate of lactate turnover in this subject while on and off phenformin therapy suggests that a prime factor leading to the elevated lactate levels in this situation in impaired peripheral aerobic metabolism. Although lactate oxidation was increased in the presence of phenformin, the control studies clearly demonstrate that aerobic metabolism was not keeping pace with the increased level of anaerobic carbohydrate metabolism brought on by the drug. It is concluded that it is this imbalance in lactate metabolism that is responsible for the lactic acidosis that accompanies phenformin therapy.

Acidosis↗
PubMed1977

Phenformin-associated pancreatitis.

Although phenformin has been previously reported to be associated with acute pancreatitis, little emphasis of this association has been made in the literature. We report the case of a 70-year-old diabetic man who developed acute hemorrhagic pancreatitis and severe lactic acidosis while taking phenformin. The patient was not taking any other medications, nor did he have any of the known metabolic conditions associated with pancreatitis. We review the four previously published cases of patients who developed acute pancreatitis while taking phenformin. Three of those patients also developed lactic acidosis, a well-known complication of phenformin therapy. Although phenformin has been reported to increase the serum amylase activity and to alter the content of the pancreatic secretions in response to various stimuli, the manner in which the drug might cause acute pancreatitis remains completely unknown.

Acidosis↗
PubMed1978

The effects of phenformin in normal vs. diabetic isolated perfused rat liver.

In the isolated perfused liver system high concentrations of phenformin (0.93--1.24 mM) were required to reduce the greater than two-fold elevated rate of gluconeogenesis from L-[U-14C]lactate in acutely alloxan diabetic (48-hour) and chronically alloxan diabetic (7-day) rat livers to the slower rate of normal fed livers. At these phenformin concentrations, other hepatic functions such as substrate uptake and 14CO2 production were also inhibited. The livers were also in a very reduced state under these conditions as indicated by the elevated ratios of the redox couples lactate/pyruvate and 3-hydroxybutyrate/acetoacetic acid. The results are interpreted to indicate that if phenformin functions as an antidiabetic (hypoglycemic) agent by inhibiting hepatic gluconeogenesis to normal levels, it is also generally toxic to the liver under such conditions. The results are discussed in relation to current hypotheses of the mechanism of action of phenformin and to phenformin-associated lactic acidosis.

Animals↗
PubMed1976

Pancreatitis and severe metabolic abnormalities due to phenformin therapy.

Two elderly diabetic patients with abdominal pain were demonstrated to have complications of phenformin hydrochloride therapy. The first developed severe lactic acidosis treated with sodium bicarbonate given intravenously and followed by rebound alkalosis. The second showed severe acidosis (specimens for lactate determination were unfortunately unsatisfactory for analysis) and similar alkalotic rebound after therapy. She then developed severe pancreatitis, proved at operation, no cause for which other than phenformin was apparent. Poor renal and hepatic function predispose to these conditions by increasing serum phenformin levels and by decreasing urinary excretion of its metabolites. The acidosis should be treated judiciously with sodium bicarbonate administered intravenously. A rebound alkalosis, ensuring as the accumulated lactate is metabolized, is best treated by potassium chloride and ammonium chloride given intravenously. The mechanism by which phenformin causes pancreatitis is unknown, but termination of therapy causes cessation of the pancreatitis.

Acidosis↗
PubMed1978

Influence of phenformin and metformin on exercise induced lactataemia in patients with diabetes mellitus.

The effect of long-term treatment with phenformin and metformin respectively on blood lactate concentrations in relation to submaximal muscular exercise has been examined in 21 maturity-onset diabetics, using a cross-over method. At similar degrees of diabetic control the mean blood lactate concentration during exercise and shortly thereafter was significantly higher when the patients had received phenformin. The mean fasting lactate concentration was 1.07 mmol/l with phenformin and 1.03 mmol/l with metformin and the peak concentration was 2.56 mmol/l and 2.19 mmol/l respectively. The mean fasting blood glucose concentration before the exercise was 11.2 mmol/l with phenformin and 11.3 mmol/l with metformin; the glucose output in the urine during the preceding 24 hours was 93 mmol and 105 mmol respectively. The mean work load during exercise was 60 watts.

Adult↗
PubMed1975

Antifibrin action of phenformin.

Effects of phenformin on blood sugar, serum triglyceride, thrombin time, euglobulin clot lysis time and cardiovascular complications were studied in maturity onset diabetes and in atherosclerotic patients with or without diabetes, for a period of 14-18 months. Phenformin has shown the characteristic properties of an antifibrinopathic agent in that it prolongs thrombin time and enhances fibrinolysis. The hypoglycaemic effect of phenformin was found to be directly related to its antifibrinopathic action. Plasma lipids fell in all cases. Absence of fresh cardiovascular complications and improvement in anginal symptoms were observed. The metabolic, haematological and clinical benefits of phenformin and its limitations in maturity onset diabetes and atherosclerosis may be explained by the effects of the drug upon the thrombin-fibrinogen reaction. These results lend support to the hypothesis of a primary fibrinopathic pathogenesis in maturity onset diabetes mellitus and atherosclerosis.

Adult↗