Ultrasound-guided quadratus lumborum block for surgical treatment of endometriosis: case report.

Quadratus lumborum block (QLB) is a technique that is not widely applied for gynecological surgery. Endometriosis affects 10% of the female population and chronic pelvic pain is one of the most prevalent symptoms. Laparoscopic surgery for removal of endometriosis may present a long intra-operative duration and this technique might improve postoperative pain control. We described a case report of a patient submitted to general anesthesia associated to bilateral QLB for pelvic endometriosis. QLB was an adjuvant anesthetic technique for endometriosis, providing somatic and visceral analgesia. However, prospective studies are needed to identify the standard dosage and total duration of analgesia.

Sufentanil-2-hydroxypropyl-ß-cyclodextrin inclusion complex for pain treatment: physicochemical, cytotoxicity, and pharmacological evaluation.

Sufentanil (SUF) is a synthetic analgesic opioid widely used for the management of acute and chronic pain. This drug was complexed with 2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and the physicochemical characterization, in vitro/ex vivo toxicity assays, and pharmacological evaluation were performed. Differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR) analysis, and X-ray powder diffraction showed the formation and the morphology of the complex. Nuclear magnetic resonance afforded data regarding inclusion complex stoichiometry (1:1) with an association binding constant (K(a)) value of 515.2 ± 1.2 M(-1) between SUF and HP-ß-CD. Complexation with HP-ß-CD protected SUF from light exposure and increased its photostability. Release kinetics revealed a decrease in SUF release rate (K(rel) = 7.05 ± 0.52 and 5.61 ± 0.39 min(-1/2) for SUF-HP-ß-CD and SUF, respectively) and reduced hemolytic or myotoxic effects after complexation. Time course of tail-flick test showed that the duration of analgesia induced by SUF (150.0 ± 34.6 min) was significantly increased (p < 0.001) after complexation with HP-ß-CD (355.7 ± 47.2 min) when injected at the same dose (1 µg kg(-1)), prolonging the duration of analgesia after intramuscular administration and representing an alternative on the development of effective and safe drug-delivery system for opioid analgesics.

Study of the interaction between S(--) bupivacaine and 2-hydroxypropyl-beta-cyclodextrin.

Local anesthetics are substances able to induce pain relief by binding to the sodium channel of excitable membranes, blocking the influx of sodium ions and the propagation of nervous impulses. S(--) bupivacaine (S(--) bvc) is an amide type local anesthetic widely used in surgery and obstetrics for sustained peripheral and central nerve blockade. The present work focuses on the characterization of an inclusion complex of S(--) bvc in 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD). The complexation with HP-beta-CD has been investigated using reversed-phase liquid chromatography and solubility isotherms. The retention behavior was analyzed on a reversed phase C18 column and the mobile phase used was acetonitrile-phosphate buffer pH 7.4 (10mM), (45/55, v/v), in which HP-beta-CD was incorporated as a mobile phase additive. The decrease in the retention times with increasing concentration of HP-beta-CD enables the determination of the complex apparent stability constants by HPLC as a function of temperature. The solubility isotherms were studied as a function of pH (7.4 and 10.5) and temperature. The pH study showed that S(--) bvc reaches a concentration at least 1.5 and 4.5 times higher (pH 7.4 and 10.5, respectively) than the one presented by the free drug in water. The calculated values for the apparent stability constant (K) are 13.1+/-2.8 and 95.4+/-11.8M(-1) for pH 7.4 and 10.5, respectively, thus indicating the formation of a stable complex. In addition, the study of the apparent stability constant by HPLC and solubility isotherm gives thermodynamics information about the interaction between S(--) bvc and HP-beta-CD. The application of the continuous variation method indicated the presence of a complex with 1:1 S(--) bvc:HP-beta-CD stoichiometry. This is an important study for the characterization of potential formulations to be used as therapeutic options for the treatment of pain.