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Biomedical subjects

M J Arias

Publications and source records attributed to M J Arias.

At least 19 recordsLinked to original sources
PubMed2000

Study of omeprazole-gamma-cyclodextrin complexation in the solid state.

The possibility of obtaining inclusion complexes between omeprazole (OME) and gamma-cyclodextrin (gamma-CD) by kneading, spray-drying, coprecipitation, and freeze-drying was evaluated. All these methods lead to the isolation of a true inclusion compound, as evidenced by differential scanning calorimetry (DSC), infrared spectroscopy, and X-ray diffractometry on powder (PXRD). Moreover, PXRD and scanning electron microscopy (SEM) afforded data concerning crystallinity and surface characteristics of the solid phases obtained. In all cases, a significant increase of the release rate with respect to the drug alone was found, and it was attributed to the formation of an inclusion compound. Among the solid phases obtained, the comprecipitated product presented the highest dissolution rate.

Anti-Ulcer Agents↗
PubMed1999

Effects of the host cavity size and the preparation method on the physicochemical properties of ibuproxam-cyclodextrin systems.

The effect of cyclodextrin (Cd) complexation on ibuproxam (IBUX) dissolution properties was studied by evaluating both the influence of Cd cavity size and the preparation method used for obtaining solid inclusion complexes. Binary systems of IBUX with natural Cds, prepared using different techniques (kneading, sealed-heating, spray-drying), were studied by differential scanning calorimetry (DSC), hot-stage microscopy (HSM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and their dissolution behavior was evaluated according to the dispersed amount method. The nature and the dissolution performance of the end product appeared to be related to both steric factors of host molecule and preparation method of the solid system. The alpha Cd cavity size was less suitable for accommodating the IBUX molecule, whereas spray-drying and sealed-heating methods led to a true inclusion complex of IBUX in the beta Cd and gamma Cd cavity. In contrast, the kneading method did not lead in any case to a real inclusion complex. Spray-dried systems with beta Cd and gamma Cd were the most effective in achieving the enhancement of the IBUX dissolution rate.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1996

Dissolution properties and in vivo behaviour of triamterene in solid dispersions with polyethylene glycols.

The applicability of the solid dispersion technique as a method for enhancing the GI absorption of a drug has been explored in order to procure better dissolution characteristics and better bioavailability for triamterene. The physicochemical characterization of the systems has shown the absence of chemical reaction between the drug and the polymers during the solid dispersion elaboration process (melting carrier method). In vitro release profiles have been studied and quantified in terms of dissolution efficiency over the first 30 min (DE30) and dissolution percentage over the first 30 min (DP30). The results have shown that there were no significant differences between the three polyethylene glycols (PEGs) under test. The in vivo effectiveness of the different preparations was also investigated by means of the urinary volumetric excretion (UVE)--pharmacologic effect--and by the estimation of Ke, tmax, and MRT-pharmacokinetic parameters. At end, an analysis of the relative bioavailabilities between formulations has been performed.

Animals↗
PubMed1994

The application of solid dispersion technique with D-mannitol to the improvement in oral absorption of triamterene.

Present paper proposes a new system to administer triamterene, a sparing potassium diuretic which presents absorption problems when administered as a free powder, due to its low solubility in water. To increase the dissolution rate and subsequent oral bioavailability of this drug, it has been formulated as solid dispersion. This method involves preparation by the melting carrier method using D-mannitol as matrix. These systems were subjected to USP XXII dissolution rate determination. The results revealed a marked dissolution rate increase of included triamterene in solid dispersions when compared with micronized drug. Further in vivo assays have demonstrated the absorption efficiency for the proposed systems when referred to pure drug. In vitro-in vivo correlation between the parameter T80% (from dissolution rate studies) and the pharmacokinetic one Ke, has found to be acceptable. All the results obtained make this system suited for further formulation in the pharmaceutical industry.

Administration, Oral↗
PubMed1987

Treatment of experimental spinal cord injury with TRH, naloxone, and dexamethasone.

Comparison of thyrotropin-releasing hormone (TRH), naloxone, and dexamethasone treatments in experimental spinal cord injury was studied in albino rats. Animals were made paraplegic by the application clip method of Rivlin and Tator. Treatment was administered intraperitoneally as a bolus injection in two doses at 45 and 120 minutes each after the injury. Animals were allocated randomly to one of four experimental treatment groups: (1) TRH (0.6 mg of TRH per dose) (2) naloxone (0.8 mg per dose), (3) dexamethasone (0.6 mg per dose), and (4) saline. Neurologic recovery was assessed by the inclined plane method, and cavitation size of the cord and of the pyramidal tract was examined under the light microscope. Results show that TRH and naloxone are therapeutically beneficial in the treatment of spinal cord injury, and that dexamethasone is ineffective.

Animals↗
PubMed1987

Morphometry of the pyramidal tract in the spinal cord of normal rats.

A morphometric study of the pyramidal tract at the spinal cord level in the normal albino rat is reported. The area, perimeter, axonal and glial cell count, and axonal concentration were determined at the seventh cervical, second thoracic, and third lumbar spinal cord levels. The results show consistent diminishing values of the area, axonal and glial cell count, and axonal concentration with the tract descent in the spinal cord.

Animals↗
PubMed1986

Percutaneous radio-frequency thermocoagulation with low temperature in the treatment of essential glossopharyngeal neuralgia.

Two cases of essential glossopharyngeal neuralgia treated successfully with percutaneous radio-frequency thermocoagulation are reported. In order to avoid cardiovascular complications due to interference with the vagus nerve, a modification of the technique previously used is proposed. The modification used in the cases presented here consists in the use of lower temperature during a shorter time with four progressive steps controlled with electrical stimulation. A small-surface active electrode, exact location in the petrous ganglion, permanent stimulation control, and a smaller thermal lesion are the cardinal features of the technique used in the cases reported.

Dermatologic Surgical Procedures↗
PubMed1986

Acute spinal cord compression by spontaneous subarachnoid haematoma.

An unusual case of spontaneous spinal subarachnoid haematoma (SAH) is reported. A 42-year-old man developed sudden and excruciating back pain immediately after sitting up from a supine position, and meningeal irritation and spinal cord compression signs of then appeared. Myelography disclosed a filling defect of contrast column at T2 level. After prompt surgical evacuation neurological function was totally regained. Physiopathology and diagnosis are discussed with reference to similar cases in literature.

Adult↗
PubMed1986

Percutaneous retrogasserian glycerol rhizotomy for trigeminal neuralgia. A prospective study of 100 cases.

A prospective study of percutaneous retrogasserian glycerol rhizotomy (PRGR) with and without metrizamide trigeminal cisternography is reported in the treatment of the trigeminal neuralgia. A series of 100 patients with typical trigeminal neuralgia were allocated randomly to two treatment groups: Group I patients received PRGR with trigeminal cisternography (50 cases) and Group II patients received PRGR without trigeminal cisternography (50 cases). The results indicate that PRGR without trigeminal cisternography is a valid alternative to the original technique. Factors that assured the accurate performance of the modified technique proposed in this study were: spontaneous cerebrospinal fluid drainage; radiologically confirmed placement of the thin spinal needle at the clival edge into the trigeminal impression of the petrous apex and in the center of the foramen ovale; a positive response to the glycerol test; clinical control of the final glycerol injection; and an alert and cooperating patient throughout the entire procedure.

Adult↗
PubMed1985

Effect of naloxone on functional recovery after experimental spinal cord injury in the rat.

The effect of the opiate antagonist naloxone on the functional recovery of rats injured with a 10 g-cm impact to the spinal cord at the T-3 level is studied. Sixteen rats were treated with 0.8 mg of naloxone in an intraperitoneal bolus 45 and 120 minutes after injury, 16 rats were given 4 mL of saline instead of naloxone, and 16 rats were neither injured nor treated. To asses weekly the motor recovery of the injured animals, the inclined plane method was employed. After the 10-week assessment period, naloxone-treated animals showed a significantly better performance on the inclined plane than saline-treated animals. Naloxone may be useful for the treatment of spinal cord injury although its mechanism of action remains unknown.

Animals↗
PubMed1985

Bilateral traumatic abducens nerve palsy without skull fracture and with cervical spine fracture: case report and review of the literature.

Bilateral traumatic abducens nerve palsy is a rare condition. Here a case without skull fracture and associated with cervical spine fracture is reported. Only two cases like this were found in a review of the literature. The mechanism of the lesion is discussed in light of the two main theories proposed thus far. When the injury is acute, as happens in the majority of cases, the nerve lesion probably is due to contusion and stretch of the nerve trunk against the ridge of the petrous bone and the rigid dural hole of entrance in the extradural space at the basilar process.

Abducens Nerve Injury↗
PubMedDate not supplied

Improvement of the diuretic effect of triamterene via solid dispersion technique with PEG 4000.

The present investigation was designed and undertaken in order to substantiate further contention concerning the universality of the utilization of PEG polymers as matrix carriers. This study could then be considered an attempt to enhance the dissolution rate of triamterene, with the subsequent enhancement in its absorption rate, via solid dispersion using PEG 4000. The approach of solid dispersions was found useful for optimizing the pharmacokinetic of triamterene in rats.

Administration, Oral↗