The status of metformin in Canada.

During the 1970s two biguanide drugs, phenformin and metformin, were used to control hyperglycemia. Phenformin was phased out of the Canadian market because it carried an unacceptable risk of causing lactic acidosis, but metformin remains available. All documented cases of lactic acidosis associated with metformin administration, which are rare, have occurred abroad in patients who were taking the drug in spite of having contraindications to its use. The two drugs are metabolized differently, phenformin being deactivated and concentrated in the liver, and metformin being excreted rapidly, unchanged, by the kidneys. In properly selected diabetic patients therapeutic doses of metformin do not raise the blood levels of intermediary metabolites enough to induce ketoacidosis or lactic acidosis. The safety of the drug is supported by the clinical experience over about 56,000 patient-years in Canada.

Oral contraceptives and endocrine changes.

In groups of women taking oral contraceptives and in control groups of women, the serum levels of cortisol, protein-bound iodine, and total thyroxine were measured together with the T(3) binding index. The daily excretion in the urine of free cortisol, 17-hydroxycorticosteroids, 17-ketosteroids, pregnanediol, pregnanetriol, total oestrogens, total catecholamines, and 4-hydroxy-3-methoxymandelic acid was also assayed. The frequency distribution of the values obtained indicates that oral contraceptives have a marked influence on the endocrine environment. The smallest deviations were observed in urinary excretion of total catecholamines and of 4-hydroxy-3-methoxymandelic acid. In some individuals the hormone assays were continued throughout the menstrual cycle. The morning and afternoon levels of serum cortisol tended to increase during the period when the oral contraceptive was being taken.

Polycystic ovaries associated with congenital adrenal hyperplasia.

Polycystic ovaries were found in a 16-year-old female with congenital absence of vagina, male-like external genitalia, and congenital adrenal hyperplasia. Masculinization was sufficiently severe to cause the patient to be reared as a male. Biochemical studies of ovarian tissue revealed hyperactivity and an imbalance of enzyme systems concerned with steroid-hormone biosynthesis, which led to production of large amounts of androgens. The pathway towards estrogens was preserved but less efficient than normal. Urinary steroid metabolites before and after hysterectomy and bilateral salpingo-oophorectomy revealed an absence of Porter-Silber chromogens and tetrahydrocortisone. Excretion of aldosterone was normal and that of corticosterone slightly higher than normal. The patterns of urinary 17-ketosteroids, pregnanediol, pregnanetriol and pregnanetriolone were similar to those commonly seen in congenital adrenal hyperplasia with steroid 21-hydroxylase deficiency. Urinary estrogens after panhysterectomy were low, being in the post-menopausal range. The pathogenesis of polycystic ovaries and their possible contribution to masculinization are discussed.