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Biomedical subjects

M V Rudorfer

Publications and source records attributed to M V Rudorfer.

71 records · Page 4Linked to original sources
PubMed1984

The effect of short term lithium administration on suppressibility of parathyroid hormone secretion by calcium in vivo.

We performed graded calcium infusions twice in six normal young men, once without medication and a second time after they had received therapeutic doses of lithium carbonate for 5 days. The serum lithium level was 0.73 +/- 0.08 meq/liter (mean +/- SE) at the beginning of the calcium infusion and reached 0.97 +/- 0.13 150 min after receiving a lithium dose (210 min after beginning the test). There was no significant difference in mean basal serum calcium, plasma PTH, or nephrogenous cAMP for the untreated and treated periods. There was also no significant difference in calcium suppressibility of PTH secretion, as reflected by changes in nephrogenous cAMP. Changes in plasma PTH in response to calcium infusion likewise did not differ for the two periods, with the exception of a slightly greater degree of suppression in the unmedicated state (77% vs. 57% on lithium: P less than 0.02, by paired t test) at the last time point of the calcium infusion. The data show that short term administration of therapeutic doses of lithium does not alter the set-point for calcium suppression of PTH secretion in man. Further studies of calcium suppressibility of PTH secretion in subjects receiving long term lithium therapy will be needed to evaluate the pathophysiology of lithium-induced hypercalcemia.

Adult↗
PubMed1984

Reduction of norepinephrine turnover by serotonergic drug in man.

Zimelidine (ZIM), a relatively specific serotonin reuptake inhibitor, was administered to 12 hospitalized healthy young male volunteers. Chronic but not acute ZIM caused a modest (23%) but significant elevation of plasma norepinephrine (NE) measured in the standing but not in the supine position. The 24-hr urinary excretion of NE itself was unchanged on chronic drug, whereas "whole-body" NE turnover was reduced by 1 week of ZIM, as evidenced by lowered excretion rates (both individually and summed with NE) of the metabolites 3-methoxy-4-hydroxyphenylglycol (MHPG), normetanephrine (NM), and vanillylmandelic acid. Lack of effect of ZIM on the NM/MHPG excretion ratio (which is increased by desipramine) indicated that ZIM and its major metabolite, horzimelidine (NZIM) are not acting by NE reuptake blockade. These data are consistent with modulating serotonergic influence on the noradrenergic system. Reduction of NE turnover and increasing the efficiency of the NE neurotransmission may be a common pathway of all clinically effective antidepressant treatments.

Adult↗
PubMed1984

Active metabolites of antidepressants: pharmacodynamics and relevant pharmacokinetics.

This chapter offers a current assessment of the relevance of new findings on the pharmacodynamics and pharmacokinetics of active metabolites of the tricyclic antidepressants. The assessment of TCA actions that may be additive, synergistic, or antagonistic requires precise knowledge of pharmacodynamic potency and control of pharmacokinetic behavior. Simple assumptions about the behavior of ratios of active forms across the populations are inappropriate. Careful pharmacokinetic control is necessary, especially considering that such variables as age, race, illness and other drugs can subtly influence the overall effect by influencing a single active form. The hydroxy metabolites are most susceptible since both their formation and elimination utilize independent variable pathways. Nonetheless, it is now possible to quantitate all known active forms of TCAs. Clinical investigation of the relationship between these forms and specific biochemical effects should provide advances in our understanding of antidepressant mechanisms. On the basis of available data of this type, we conclude that an intensified effort to understand effects secondary to NE uptake inhibition alone would be especially valuable.

Adult↗
PubMed1984

Second-generation antidepressants.

The host of newly developed antidepressant drugs offer important clinical advantages to some patients, although their promises of improved therapeutic efficacy and reduced adverse effects compared with conventional treatments are not fully realized. Increased biochemical specificity and unique mechanistic or clinical profiles render these compounds valuable in research into the pathophysiology of affective disorders and mode of action of antidepressant agents.

Alprazolam↗
PubMed1984

Effects of chronic desipramine on plasma norepinephrine concentrations and cardiovascular parameters in elderly depressed women: a preliminary report.

The effect of chronic administration of desipramine, a relatively specific inhibitor of the reuptake of norepinephrine (NE), on heart rate, blood pressure, and concentrations of NE in plasma was examined in elderly depressed women. Plasma NE concentrations rose significantly following administration of desipramine, while there was no significant change in either heart rate or blood pressure. Implications of these findings are discussed with relationship to the selection of appropriate types and doses of antidepressants in the elderly.

Aged↗
PubMed1983

Effects of serotonin on memory impairments produced by ethanol.

Subjects treated with low or high doses of ethanol demonstrated impaired memory, particularly in tests involving the recall of poorly learned information. Zimelidine, an inhibitor of serotonin reuptake, reversed this ethanol-induced impairment. The serotonin neurotransmitter system may mediate learning and memory in humans and may determine some of the effects of alcohol on higher mental functions.

Adult↗
PubMed1982

Cardiovascular changes and plasma drug levels after amitriptyline overdose.

Electrocardiographic and blood pressure parameters in 17 patients after amitriptyline overdose were reviewed in a retrospective study. Seven patients for whom baseline electrocardiograms (EKGs) were available showed significant increases in heart rate and QRS duration after overdose. Ventricular arrhythmias were observed in only one case, the sole fatality, who demonstrated the highest amitriptyline plus nortriptyline plasma level. Most patients experienced sinus tachycardia (88%) and hypotension (53%). Widened PR and QRS after overdose also were common. For the total group, postoverdose TCAD levels correlated with PR (r = .66, p less than .01) and QRS (r = .55, p less than .05) values, and with lowest observed systolic (r = -.60, p = .01) and diastolic blood pressure (r = .50, p less than .05) but not QTc or heart rate. The difference between the mean TCAD levels of subjects with lowest systolic blood pressure less than 100 mmHg and those with higher readings was significant at the 0.05 level.

Adolescent↗
PubMed1982

Dexamethasone suppression test in primary depression: significance of family history and psychosis.

The overnight dexamethasone suppression test (DST) was administered to 31 inpatients with endogenous depression. DST results were abnormal in 42% of the group and in 67% of those patients with psychotic depression. Division of the sample into genetic subtypes based on family history criteria of Winokur et al. failed to replicate his group's DST findings. Subjects with sporadic depressive disorder, especially delusional patients, had a higher rate of dexamethasone nonsuppression than the others. Familial pure depressive patients did not show the expected greater frequency of DST abnormality compared to the depression spectrum disorder group.

Adolescent↗
PubMed1982

Amitriptyline overdose: clinical effects on tricyclic antidepressant plasma levels.

Tricyclic antidepressant (TCA) plasma levels after amitriptyline overdose were reviewed in a retrospective study. Amount of drug taken correlated with total TCA levels. Plasma concentrations were higher in blacks than whites, but no association could be found between TCA levels and age or sex of patients. History of routine use of amitriptyline at the time of overdose did not predict TCA levels, but the one fatality could be shown on the basis of previous steady-state levels to be a slow metabolizer. Serious overdoses as documented by high plasma TCA levels were seen in all major diagnostic groups.

Adolescent↗
PubMed1980

Anticholinergic effects and plasma desipramine levels.

Anticholinergic effects of the tricyclic antidepressant desipramine were studied in 12 outpatients. Objective measurements of salivation and pulse rate and subjective ratings of mouth dryness and palpitations were made before and during treatment with desipramine at a final daily dosage of 150 mg. There were significant changes after 3 wk of treatment in all parameters except ratings of palpitation. Subjects with moderate or high plasma desipramine levels had more suppression of salivation than those with low levels. Changes in salivation and pulse did not correlate, nor did they correlate with subjective reports.

Adult↗