Biomedical subjects

G A Fast

Publications and source records attributed to G A Fast.

4 recordsLinked to original sources

PubMed1992

Tricyclic antidepressant-induced seizures and plasma drug concentration.

BACKGROUND: This study identifies eight patients who during routine therapy with conventional doses of tricyclic antidepressants (TCAs) experienced elevated plasma concentrations and suffered a grand mal seizure. We correlate the incidence of TCA-induced seizures with TCA plasma level and suggest that the incidence of TCA-induced seizures can be significantly reduced with the judicious use of therapeutic drug monitoring. METHOD: Seven of the eight cases of TCA-induced seizures during routine pharmacotherapy represent all the cases known to the authors during their careers. Histories were evaluated for factors that would predispose patients to suffer seizures. The following data were also recorded: (1) duration of treatment with the dose that was associated with the seizure, (2) the time between last dose and the seizure, (3) a plasma TCA level obtained at the time of seizure, and (4) presence or absence of other manifestations of TCA toxicity. In addition, a MEDLINE search was conducted using the key phrases "tricyclic antidepressants" and "seizures" to obtain all English language articles published since 1966 on the occurrence of TCA-induced seizures. RESULTS: The mean +/- SD daily TCA dose was 250 +/- 80 mg/day. The mean +/- SD total plasma TCA concentration was 734 +/- 249 ng/mL (range, 438-1200 ng/mL). The only risk factor that emerged for experiencing seizures was an elevated plasma TCA concentration. Three patients presented with no other manifestations of TCA toxicity prior to seizure. CONCLUSION: The incidence of TCA-induced seizures for our inpatient population in which therapeutic drug monitoring is routinely used is 0.4%. This incidence is less than that reported in earlier inpatient series (1% to 4%). Our finding is consistent with the conclusion that therapeutic drug monitoring reduces the incidence of TCA-induced seizures by allowing for rational dose adjustment.

Adult↗

PubMed1991

Therapeutic drug monitoring for antidepressants: efficacy, safety, and cost effectiveness.

Therapeutic drug monitoring (TDM) of tricyclic antidepressants (TCAs) is a cost-effective tool to increase efficacy and safety in patients suffering from major depressive illness. The concentration:antidepressant response relationships of nortriptyline, desipramine, and amitriptyline conform to a curvilinear relationship between concentration:antidepressant response; whereas, imipramine conforms to a linear relationship. Besides improving efficacy, TDM identifies the subset of patients who are at risk to develop excessive plasma TCA levels with potential resultant central nervous system and cardiovascular toxicity. Taking both the efficacy and safety data into account, cost:benefit analyses demonstrate that TDM is cost effective when used once as a standard aspect of care in the TCA treatment of patients with major depressive illness.

Age Factors↗

PubMed1985

Extra-high-frequency auditory thresholds: fine structure, reliability, temporal integration and relation to ear canal resonance.

Three trained subjects were repeatedly tested for detection of auditory thresholds at 27 frequencies, from 2 to 18 kHz. A double-blind procedure was used with the method of adjustment, and the quasi-free-field delivery system of Osterhammel et al. [Scand. Audiol. 6:91-95, 1977] was used to monaurally stimulate the ear. A very reliable series of high- and low-threshold changes, termed the fine structure of the extra-high-frequency audiogram, was observed from 8 to 16 kHz. All 6 ears had a major low-threshold region at or near 13.5 kHz, and up to 3 other replicable sensitive frequencies along this one octave range. Thresholds were invariant over 3 conditions of stimulus presentation (constant tone; 500 ms duration, 25 ms rise and decay, 1 s interstimulus interval; and 100 ms duration, 1.5 ms rise and decay, 200 ms interstimulus interval). As the duration of the tone was decreased from 100 to 5 ms, temporal integration (an average of approximately 2.5 dB threshold increase as the duration was halved) was noted. Although temporal integration was slightly less at higher frequencies, the shape of the audiograms remained essentially unchanged as the stimulus duration was decreased to 5 ms. There was no consistent relationship between the maximally sensitive high frequencies and the amount of temporal integration. But there was a general association between the maximally sensitive high frequencies and the resonant frequency characteristics of that particular ear.

Adult↗

PubMed1984

Ultrahigh-frequency auditory thresholds in young adults: reliable responses up to 24 kHz with a quasi-free-field technique.

A quasi-free-field technique was used to assess detection thresholds to pure tones, at frequencies ranging from 2 to 24 kHz. The sound delivery system of Osterhammel et al. [Scand. Audiol. 6:91-95, 1977] was modified in order to deliver constant stimuli at SPLs of at least 117 dB over the entire frequency range. A modified form of the method of adjustment maintained the subjects' interest, and a double-blind procedure minimized experimenter and subject bias. In the first experiment, 78 university subjects from Northern California (18-24 years old) were exposed to tones in 2-kHz increments. All but 12 of these persons could reliably detect the highest frequency, with females being slightly more sensitive. But from 10 to 20 kHz, there were no differences between the sexes. In a second group of 20 students, tested in 1-kHz increments from 8 to 16 kHz, the previously observed 10- to 14-kHz threshold plateau was revealed as a pronounced 13-kHz low-threshold region. The threshold at this frequency was approximately 14 dB lower than the 11-kHz threshold. These data were compared with those obtained in a similar fashion from other cultures.

Adolescent↗