Atropine pharmacokinetics are affected by moderate hemorrhage and hypothyroidism

Prostaglandins may participate in opioidergic and cholinergic control of the diurnal changes of tuberoinfundibular dopaminergic neuronal activity and serum prolactin level in ovariectomized, estrogen-treated rats

The roles of prostaglandins (PGs) involved in opioidergic, cholinergic, and serotonergic regulation of the diurnal changes of tuberoinfundibular dopaminergic (TIDA) neuronal activities were investigated in ovariectomized, estrogen-treated rats. Treatment with naloxone [10 mg/kg, intraperitoneal (i.p.)], atropine (5 mg/kg, i.p.), or ketanserin (10 mg/kg, i.p.) at either 1200 or 1400 h prevented the afternoon decrease of TIDA neuronal activity and the prolactin (PRL) surge. Intracerebroventricular (i.c.v.) injection of PGE(1) (5 microg/3 microl/rat) at 1500 h significantly reversed the effects of naloxone and atropine, but not that of ketanserin. In ovariectomized, estrogen-primed rats pretreated with indomethacin, i.c.v. injection of either nicotine (10 ng/rat) or fentanyl (10 ng/rat) failed to suppress the TIDA neuronal activity and to stimulate the PRL secretion. These data suggest that PG may be involved in opioidergic and cholinergic control of the diurnal changes of TIDA neuronal activity and the PRL secretion in ovariectomized (OVX) + E(2) rats.

Co-amoxiclav pharmacokinetics during posttraumatic hemorrhagic shock

OBJECTIVE

To determine the effects of severe trauma with hemorrhagic shock on amoxicillin and clavulanate concentrations in plasma and their pharmacokinetics.

DESIGN

A prospective, open, descriptive study.

SETTING

A 12-bed, adult surgical intensive care unit in a university-affiliated hospital in France.

SUBJECTS

Subjects were 12 patients (10 men, 2 women) with severe trauma: median (range) Injury Severity Score, 38 (17-48); Acute Physiology and Chronic Health Evaluation II, 16 (7-38); Simplified Acute Physiology Score II, 41 (23-77). Also enrolled were 12 healthy volunteers who were matched on age (+/-5 yrs), gender, and body-surface area (+/-20 cm2). All the trauma patients suffered hemorrhagic shock defined as the association of at least one episode of systolic blood pressure <90 mm Hg and an intravascular volume expansion >2000 mL between trauma and surgery.

INTERVENTION

Prophylactic perioperative administration of 2 g of amoxicillin and 0.2 g of clavulanate in combination during the first 12 hrs posttrauma in patients, and at the start of the pharmacokinetic study in volunteers.

MEASUREMENTS AND MAIN RESULTS

Serial plasma samples (n = 13) were obtained after the first antibiotic administration to measure antibiotic levels by using high-performance liquid chromatography assays. Compared with volunteers, trauma patients had higher plasma amoxicillin and clavulanate concentrations, attributed to a reduction of the volume of distribution (p =.001 and p =.06, respectively) and, to a lesser extent, of the total body clearance (p =.09 and p =.20, respectively). Consequently, amoxicillin and clavulanate elimination half-lives were similar for the two groups of subjects. The interindividual variabilities for all the amoxicillin pharmacokinetic parameters were higher in patients.

CONCLUSIONS

In trauma patients with hemorrhagic shock requiring surgery, the administration of 2 g of amoxicillin and 0.2 g of clavulanate seems adequate, according to the antibiotic concentrations observed in plasma for both drugs. However, further studies exploring antibiotic concentrations in tissues are warranted.

The influence of hemorrhagic shock on the pharmacokinetics and the analgesic effect of morphine in the rat

The influence of hemorrhagic shock (removal of 30% of the blood volume) on the pharmacokinetics and the analgesic effect of morphine was investigated in conscious rats. Plasma concentrations of morphine after a bolus injection (5 mg/kg) are higher in the shock animals, which is attributed to a small decrease in clearance (-22%; P > 0.05) and a significant decrease in distribution volume (-33%; P < 0.05) of the drug. The areas under the plasma concentration-time curve of the metabolite morphine-3-glucuronide (M3G) are significantly higher (+237%; P < 0.01) in the shock rats, which is probably explained by a decreased distribution and renal excretion. The analgesic effect of morphine was evaluated using the tail-flick test during a continuous infusion (10 mg/kg/h) with measurement of the plasma concentrations of morphine and M3G. Data from these experiments show higher plasma concentrations of morphine (+33%; P < 0.05) and M3G (+66%; P > 0.05) during shock, and a significantly increased analgesic effect (+43%; P < 0.05). Our data suggest that the increased analgesic effect of morphine during hemorrhagic shock can most likely be explained by pharmacokinetic changes resulting in higher morphine concentrations.