Patient-controlled analgesia (PCA) is a relatively new therapeutic modality that allows patients to administer doses of intravenous narcotics, using a syringe pump and sequencing device. We used PCA to deliver analgesic therapy to a 35-year-old man seriously injured in an aviation accident. Although the patient gave no previous history of narcotic use or abuse, he required morphine dosing rates as high as 56 mg/h to maintain adequate analgesia. The delivery of relatively high doses of narcotic was not accompanied by significant sedation, as might be expected. The patient underwent two surgical procedures while on PCA therapy. Following each procedure, dosing requirements increased, but within three days after each operation, dosing tapered. The patient was converted to oral hydromorphone therapy, which gradually was tapered and then discontinued. PCA should be considered a useful therapeutic adjunct in the management of patients refractive to empirical narcotic analgesic regimens.

Adult↗

PubMedDate not supplied

Relationship between plasma morphine concentrations and pharmacologic effects in postoperative patients using patient-controlled analgesia.

In postoperative patients using patient-controlled analgesia (PCA) to administer i.v. doses of morphine sulfate, respiratory rates and subjective rankings of pain, sedation, and liking for the drug were correlated with plasma morphine concentrations. In 12 patients selected before surgery, the initial morphine sulfate dose of 0.6 mg/sq m was increased or decreased as needed. Every two hours, cumulative morphine sulfate dose, respiratory rate, and sedation were recorded by the nurse, along with the patient's evaluation of pain and liking for the drug. Plasma was collected in the morning and evening during PCA therapy for morphine analysis. Data were analyzed by analysis of covariance. Dosing rates and rankings of pain, sedation, and liking decreased as a function of time postoperatively, but respiratory rates did not. Sedation and respiratory rates were independent of morphine concentration. Liking of the drug increased directly with plasma morphine concentration but decreased with time. A high level of pain was directly related to morphine use. For all significant relationships, there was high interpatient variability, with the exception of changes in pain rankings induced by morphine. Patients defined a minimum effective plasma morphine concentration of 20-40 ng/mL. The maximum plasma morphine concentration achieved by self-administration was 82 ng/mL. These postoperative patients used patient-controlled analgesia to deliver morphine sulfate i.v. for pain relief, not for euphoria, and did not exhibit sedation or respiratory depression. Morphine was consistently effective at plasma concentrations of 40 ng/mL or greater.

Adult↗

PubMedDate not supplied

Patient-controlled analgesia: dose increments and equianalgesic doses.

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Analgesics, Opioid↗

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Morphine requirements using patient-controlled analgesia: influence of diurnal variation and morbid obesity.

The influence of diurnal variation and morbid obesity on the morphine requirements of patients using patient-controlled analgesia (PCA) was studied. Forty-six patients undergoing either elective (Group I) or gastric bypass (Group II) surgery composed the study group. Patients were allowed to use the PCA machine for 36 to 72 hours postoperatively to deliver 0.6 mg/sq m doses of morphine sulfate intravenously. Counters on the device indicating the number of doses received were monitored every two hours along with vital signs and a pain and sedation rating. Dosing rates were studied with regard to the time of day. Morbid obesity had no significant effect on dosing rate requirements. Analyses revealed a significant diurnal rhythm in morphine dosing rate requirements despite a 27-fold interpatient variability. Peak analgesic use was at 0900, and the nadir was at 0300. Patient pain rankings did not indicate any changes in pain status, demonstrating PCA's use of analgesia as an endpoint for dosing. Sedation status showed a higher degree of sedation at night when compared with the daytime values, documenting that sedation was not drug-induced. There is a circadian variation in narcotic analgesic need in the postoperative patient that is met appropriately by PCA.

Adult↗

PubMedDate not supplied

Comparative bioavailability of chlorpropamide tablet and suspension formulations.

The bioavailability of a chlorpropamide tablet formulation chlorpropamide tablet formulation was assessed by comparing it to a reference suspension of chlorpropamide. Eighteen healthy adult men received chlorpropamide 250 mg as a tablet (Diabinese, Pfizer) and suspension in an open two-way crossover study of Latin-square design with a 14-day washout period between treatments. Serial blood samples were obtained by venipuncture for 96 hours for chlorpropamide serum concentration determinations. Serum glucose concentrations were determined at 0, 0.5, 1, 2, and 4 hours. The area under the serum chlorpropamide concentration-time curve (AUC), peak serum chlorpropamide concentration (Cmax), time to Cmax, and mean glucose concentration at each time point for each treatment were compared using a two-tailed Student's t test for paired data (p less than 0.05). Microrate constants for a two-compartment model for oral absorption computed using nonlinear regression were also compared. There were no significant differences between the two formulations regarding AUC, Cmax, time to Cmax, and hypoglycemic response. The absorption rate for the tablet was significantly greater than for the suspension. The results suggest that the oral chlorpropamide tablet and reference suspension are bioequivalent. Although the tablet had a faster absorption rate than the suspension, this probably is not clinically important since both formulations similarly decreased serum glucose concentration.

Adult↗