Lack of selectivity between the uptake of [3H]adrenaline and [3H]noradrenaline into rat hypothalamic slices

Therapeutic Drug Monitoring of Antidepressants

For a number of antidepressants in current clinical use, concentrations in serum or plasma are a more reliable index of target drug concentrations than is dosage. For such drugs, therapeutic drug monitoring (TDM) may be a useful clinical guide for the purpose of maximizing the likelihood of favorable therapeutic outcome while minimizing the probability of clinical ineffectiveness or adverse side effects. TDM is of greatest benefit when a therapeutic range of serum concentrations has been well established. Even if such a range is not definitively determined, TDM can be of help in situations in which patients are refractory to therapy despite adequate or high dosages, when adverse events supervene even with low doses, or when noncompliance with the intended dosage plan is suspected. Serum antidepressant concentrations from TDM should be interpreted in the full context of the patient's demographic characteristics and clinical status, along with an understanding of the pharmacokinetics of the medication being taken, the timing of the sample in relation to the dosage regimen, and the specific laboratory assay procedure. TDM measurements may be costly, and the potential benefits of the information need to be weighed against the cost to the patient or to the health care system.

Epinephrine in mammalian brain

1. Epinephrine is widely distributed in brains of various species throughout phylogeny but maintains its localization to hypothalamus and brainstem/medulla in all species studied. 2. A general decrease in brain epinephrine content is observed phylogenetically beyond fishes with wide variation within species. 3. The cellular localization of epinephrine forming enzyme is dissociated from epinephrine stores in hypothalamus where epinephrine appears to be primarily a hormone. 4. Three proposed functional pools of epinephrine are described. Synthesis of a hormonal pool and a second, perhaps nonfunctional, pool co-stored in noradrenergic terminals in the forebrain occurs extraneuronally and is probably inhibited acutely in the presence of high corticosteroids due to inhibition of uptake 2. Synthesis of epinephrine in the neuronal pool found primarily in the medulla may be enhanced due to increased PNMT activity in the presence of elevated corticosteroids. 5. Phylogenetic and pharmacological data suggest that epinephrine may play an important role in tonic regulation of the level of arousal, reward and sensitivity to environmental stimuli in mammals.