John-Fredrik Dymling

Studies on catecholamines, renin and aldosterone following Catapresan (2-(2,6-dichlor-phenylamine)-2-imidazoline hydrochloride) in hypertensive patients.

Abstract The effect of the antihypertensive compound 2-(2,6-dichlorophenylamino)-2-imidazoline hydrochloride (St 155, Catapresan®) on urinary catecholamines, plasma renin activity and urinary aldosterone was studied in patients with hypertensive diseases of different types. Catapresan induced marked lowering of blood pressure and bradycardia in all cases except phaeochromocytoma. The fall in blood pressure was closely related to a reduction in catecholamines, renin activity and aldosterone. These findings are of interest in relation to the antihypertensive effect of catapresan and also with respect to the possible role of the sympathetic nervous system for the regulation of the production of renin and aldosterone. Our studies indicate that reduced sympathetic activity with decreased production of catecholamines is at least one mode of action of catapresan. It seems possible that the reduced sympathetic activity is of importance for the diminished production of renin and aldosterone which occurs following catapresan.

Effect of danazol on thyroid function in postmenopausal women

Abstract. During treatment with danazol the serum concentration of thyroxin‐binding globulin (TBG) decreases. This effect is probably a direct effect on TBG production at the cellular level. In order to exclude an indirect effect on TBG production via the well known suppressing effect of danazol on serum estrogen concentrations, the following study was performed. Twelve healthy female volunteers, who were at least 3 years past the menopause and with serum‐estradiol levels below 100 pmol/l, were treated with danazol in dosages of 400, 600 or 800 mg daily. The concentrations of TBG, TSH, total thyroxin (T4), total triiodothyronine (T3) and free dialysable fractions of T4 and T3 were determined, before, and after 2 and 4 weeks of medications. The serum concentrations of TBG, total T4 and T3 decreased. The TSH concentration and the free dialysable fraction of T4 were essentially unaltered after 2 weeks but the TSH had decreased slightly and free T3 increased slightly after 4 weeks. The free dialysable fraction of T3 decreased transiently at 2 weeks. All the observations proved to be independent of the three dosages of danazol applied in this study. In conclusion, danazol treatment influences available tests of thyroid function by reducing the concentration of TBG. This is most probably a direct effect of the drug, and it is clearly independent of the effect on estrogen production. Clinically there is no evidence of a decreased effect of thyroid hormones on the target organs.

Osteoporosis—Possible Benefits of Treatment with Gonadal Steroids

Our group discussed osteoporosis and the possible treatment with gonadal steroids within the framework of the wider title “Estrogen replacement therapy in geriatrics”. An earnest attempt was made to limit the subject but, as normal in most discussions on osteoporosis, we did not succeed and ended up dealing with other sectors as well. We took as the starting point the common hypothesis that a correlation exists between predisposition to fracture and the absolute bone mass. ‘Absolute’ is extremely important in this context. A woman weighing 80 kg has a substantially smaller risk of incurring fractures than a woman of 40 kg. One should therefore not relate bone mass to body size when studying the risk of fractures because, although this may be intrinsically correct, it is not relevant to the predisposition for fracture.