Double-blind, placebo-controlled, pharmacokinetic and -dynamic studies with 2 new formulations of piracetam (infusion and sirup) under hypoxia in man.
In a double-blind, placebo-controlled study, pharmacokinetics and pharmacodynamics of 12 g piracetam in 2 different formulations were investigated utilizing blood gas analysis, EEG mapping and psychometry under a transient, reversible, hypoxic hypoxidosis. The latter was induced by a fixed gas combination of 9.8% oxygen (O2) and 90.2% nitrogen (N2, found in 6,000 m altitude), which was inhaled for 23 minutes under normobraic conditions by 18 healthy volunteers. They received after an adaptation session randomized at weekly intervals 12 g piracetam i.v. (250 ml infusion over 30 minutes), 12 g piracetam p.o. (60 ml sirup) and placebo. Blood levels were determined by means of an HPLC at the hours 0, 1, 2, 4, 6, 8 and 24. The 2 formulations showed a very similar time-course, with slightly higher blood levels in the 1st hour after the intravenous than oral administration, and vice versa thereafter. The elimination half-life was 4.3 hours for both formulations, the area under the curve and the clearance value were also almost identical. Evaluation of blood gases, EEG mapping and psychometry were carried out at 0, 2, 4, 6 and 8 hours post-drug. Blood gas analysis demonstrated a drop in SaO2 from 99 to 73 and 70%, in PO2 from 100 to 35 and 33 mmHg, in PCO2 from 36 to 31 and 31 mmHg in the 14th and 23rd minute of inhalation, respectively. pH increased from 7.43 to 7.48 in the respective minutes, while base excess and standard bicarbonate remained stable. EEG mapping exhibited under hypoxia a marked increase of total power, mostly due to an augmentation of delta/theta, and a decrease of alpha activity, which reflects deterioration of vigilance. Both piracetam preparations significantly attenuated this vigilance decrement, with 12 g piracetam i.v. showing its encephalotropic peak effects in the earlier hours, 12 g piracetam sirup in the later hours. At the behavioral level, hypoxic hypoxidosis induced a deterioration of the noo- and thymopsyche, which was mitigated by both piracetam preparations, mostly in the 6th hour. Both formulations were well tolerated.
Saletu
B
B
Department of Psychiatry, School of Medicine, University of Vienna, Austria.
Hitzenberger
G
G
Grünberger
J
J
Anderer
P
P
Zyhlarz
G
G
Linzmayer
L
L
Rameis
H
H
D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D001784:Blood Gas Analysis; D001921:Brain / Q000187:drug effects* / Q000503:physiopathology; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D004304:Dosage Forms; D004311:Double-Blind Method; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000503:physiopathology*; D007262:Infusions, Intravenous; D008297:Male; D010889:Piracetam / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology; D011594:Psychometrics; D011597:Psychomotor Performance / Q000187:drug effects*
D004304:Dosage Forms; D010889:Piracetam