[Lactic acidosis as a complication of treatment with biguanides]

In the course of two and a half years we treated six diabetic women on account of lactate acidosis during concurrent biguanide administration. The patients were given an average dose of 290 mg Buformin/24 hours. Their mean age was 71 years. Three patients died, i.e. the mortality was 50%. All patients reported nausea, vomiting and abdominal pain. Two suffered from diarrhoea. Two patients suffered from renal failure and one from cardiac weakness. One patient was in coma. The mean lactate concentration was 14.7 mmol/l, pH on admission was 6.84. The patients were given on average 550 mmol bicarbonate. In two instances bicarbonate dialysis was used. The authors discuss the pathophysiology, clinical aspects and importance for treatment and prevention of lactate acidosis during biguanide treatment.

[Biguanides in the treatment of diabetes mellitus]

Biguanides are useful drugs in diabetes but their indications are very precise. The danger of lactic acidosis can be avoided with the use of metformin, the less toxic of biguanides, and strict respect for contraindications. All biguanides have a similar action, through different pharmacokinetics, and besides their hypoglycemic effect, have a favourable action on blood lipids, which increases their usefulness. Haemorheological effects, recently studied in animal research, may open a new field in the employment of biguanides.

[Lactic acidosis in diabetic patients associated with buformin]

We report two diabetic patients who developed lactic acidosis following the use of Buformin. Treatment consisted of mechanical ventilation, massive bicarbonate administration, circulatory support with dopamine and peritoneal dialysis. Despite this, both patients died.

[Drug-induced harm due to antidiabetics]

A review of the complications which are of importance for the use of antidiabetic agents is given. As a consequence of too intensive a hypoglycaemic effect lesions may be provoked by sulfonylureas and insulin. Additionally, under treatment with different insulin preparations allergical side effects are possible. As an essential complication provoked by biguanides a lactic acidosis may be elicited which--though seldom occurring--then in most cases takes a fatal course. Lesions as a consequence of treatment with oral antidiabetic agents to a high degree be avoided by using them in accordance with their indication. In the case insulin the lesions ensuing immunological reactions are only to be avoided or reduced as far as the pharmaceutical industry succeeds in reducing the antigenicity of insulin preparations.

[Use of biguanide preparations in the treatment of diabetes mellitus]

The blood content of lactic acid was measured in 186 patients with overt diabetes mellitus. The patients had normal or excess body weight and were placed on different treatment methods during decompensation, subcompensation and compensation stages. During diabetes mellitus compensation attained with different treatment methods as well as during treatment including biguanides in the presence of normoglycemia, the mean blood level of lactic acid did not differ significantly from its mean content in normal subjects. Patients with decompensated diabetes mellitus manifested a significant elevation of the mean blood content of lactic acid. There was a definite relationship between the glycemia and high lactic acid level in the blood. Based on an analysis of the reported data and own materials the conclusion is drawn that biguanides should not be used in the treatment of decompensated diabetes mellitus, since this may lead to an increase in blood lactic acid and to the growth of lactic acidosis risk. It is proposed that contraindications to the use of biguanides in diabetes mellitus patients should also include hyperglycemia. Indications to the use of biguanides in diabetes mellitus patients are provided as well as the table of diseases in which biguanides are contraindicated. A list of drugs incompatible with biguanides is also presented. It is recommended that biguanides should not be applied for over 4 to 6 months. It is also recommended that detection of blood lactic acid should be introduced into medical practice on a wider basis, since lactic acidosis cannot be diagnosed without using such a test.

Biguanides. A review of history, pharmacodynamics and therapy

This review on biguanides gives a general survey of biguanide actions on many metabolic models in vivo and in vitro. It focuses especially on the comparison of the 3 antidiabetic biguanides, of which metformin is discussed as the only oral antidiabetic biguanide useful in treatment of type-II diabetes with a minimum risk of side effects when applied in a well controlled regime. Pharmacokinetics, pharmacodynamics, hypotheses on the molecular mode of action, and implications for therapy are discussed.

Malabsorption of vitamin B12 and intrinsic factor secretion during biguanide therapy

In a survey of 46 randomly selected diabetic patients on biguanide therapy, 30% had malabsorption of vitamin B12. Withdrawal of the drug resulted in normal absorption in only half of those with malabsorption. In most patients with persistent malabsorption, the results of absorption tests with exogenous intrinsic factor suggested the diagnosis of coincidental intrinsic factor deficiency. Further considerations, however, led to the concept that biguanides can induce malabsorption by two different mechanisms. One of these is temporary and unrelated to intrinsic factor secretion and the other is permanent and mediated by depression of intrinsic factor secretion.

Comparison of the bisbiguanide antiseptics alexidine and chlorhexidine. II. Clinical and in vitro staining properties

A blind cross-over trial was carried out to compare the tooth and tongue staining associated with the use of a 0.035% alexidine and a 0.2% chlorhexidine mouthrinse. Twenty-two volunteers were divided into two groups termed "tea drinkers" and "non-tea drinkers". All volunteers were requested to refrain from oral hygiene measures throughout two 10-day periods when they rinsed twice a day with the preparation randomly allocated for the respective period. During both periods the members of the groups excluded coffee, red wine and port from their diet. The tea drinking group consumed seven cups of tea per day. Tooth and tongue staining was recorded for extent and severity at the end of each period. The amount of stain accumulating in the two groups was similar following the use of chlorhexidine and alexidine. However, for both chlorhexidine and alexidine the extent and severity of tooth and tongue staining were significantly increased in the tea drinking group. An in vitro study of tea staining of perspex blocks exposed twice a day to 0.035% solutions of alexidine or chlorhexidine throughout a 5-day period demonstrated significantly more staining with alexidine when measured spectrophotometrically. Visually however, the differences in the specimens were minimal. Saliva treatment of the perspex did not significantly alter the staining by alexidine or chlorhexidine. The results provide further evidence for a dietary aetiology to the staining associated with cationic antiseptics. However, alexidine at the concentration used offered no advantage in reducing the side effect of staining when compared with chlorhexidine.

[Vitamin B12-level in serum of diabetics receiving long-term buformin therapy]

Disturbances of the vitamin B12 resorption by the therapy with biguanides above all metformin are known from literature. In 59 patients with Buformin retard-monotherapy we determined in 18.7% slight reductions of the vitamin B12 level in the serum, in one patient the serum concentration was lower than 50 pg/ml. That means that also under therapy with Buformin can be reckoned with easy disturbances of resorption for vitamin B12. Occasional controls of Hb and anamnestic establishment of neurological symptoms are to be recommended during a therapy with Buformin, in order not to overlook the clinical signs of a vitamin B12 hypovitaminosis.

[Indications and contraindications of biguanide therapy in diabetes mellitus]

In this review the actual stage of knowledge is mediated concerning the oral therapy of diabetes mellitus by biguanides. After a historical review the pharmacological data obtained by animal experiments as well as by clinical application are summarized and the effects and side-effects are derived. The problem of lactic acidosis and the controversial discussion due to the UGDP-study concerning the relation of the biguanides to the cardiovascular system are largely discussed. Concrete recommendations are given concerning the clinical practice by means of the communication of the revised indications and contraindications of the therapy with biguanides.