PubMed Health⌕ Search

Biomedical subjects

O B Larsen

Publications and source records attributed to O B Larsen.

5 recordsLinked to original sources
PubMed1985

Biochemical and diagnostic classification and serum drug levels: relation to antidepressive effect of imipramine.

The relationship between clinical effect of imipramine (IP) in 39 depressed patients and biochemical distinction, serum drug levels, and diagnostic classification was investigated retrospectively. Based on pretreatment plasma ratios of tryptophan and tyrosine to competing amino acids, which reflect the availability of the precursor amino acids to the brain, the patient sample was separated in two halfparts. The one group with low net availability of tryptophan and tyrosine improved significantly more than the other group with comparable mean serum drug levels. In the former group there was no association between clinical improvement and serum drug levels, whereas in the latter group the patients with serum IP plus desipramine (DMI) above 180 ng/ml improved significantly more than patients with lower levels. There was an indication that a serum ratio of IP:DMI below 0.2 was associated with a poor response. Patients classified as nonendogenous depressives by means of the Newcastle II scale showed about the same response pattern as endogenous depressives with comparable plasma amino acid profiles and serum drug levels. Based on amino acid patterns and serum drug levels only half of the patients received an optimal therapy on the applied schematic dosage schedule. Thus, biochemical classification rather than diagnostic may be a useful remedy for the adjustment of serum IP plus DMI to appropriate levels in individual depressives.

Adjustment Disorders↗
PubMed1983

Tryptophan and tyrosine ratios to neutral amino acids in endogenous depression. Relation to antidepressant response to amitriptyline and lithium + L-tryptophan.

The plasma ratios of tryptophan and tyrosine to those amino acids that compete with them during transport across the blood-brain barrier have been determined in depressed patients before and after treatment for four weeks with amitriptyline or lithium + L-tryptophan. There was no relation between the absolute plasma concentrations of free or total tryptophan or tyrosine and the clinical response to amitriptyline. There was also no relation between pre-treatment ratio of plasma tyrosine to competing amino acids and response to amitriptyline, but depressives with subnormal tryptophan ratio improved significantly more than patients with supernormal tryptophan ratio with comparable serum drug levels. The therapeutic response to lithium + L-tryptophan was predicted neither by the absolute plasma concentrations of free or total tryptophan or tyrosine nor by the tyrosine ratio, but there was also a trend towards greater improvement in patients with subnormal compared with supernormal tryptophan ratio. The results suggest that the pre-treatment plasma ratio of tryptophan to competing amino acids is a useful predictor of clinical response to amitriptyline. The possible mode of action of amitriptyline and lithium + L-tryptophan is briefly discussed.

Amino Acids↗