PubMed Health⌕ Search

Biomedical subjects

A M Rabasco

Publications and source records attributed to A M Rabasco.

23 records · Page 2Linked to original sources
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↗
PubMed1993

Protection by alpha-tocopherol against skin necrosis induced by doxorubicin hydrochloride.

Extravasation of doxorubicin hydrochloride during i.v. infusions can cause serious local complications due to the action of free radicals which are produced as a result of this leakage. An experiment was carried out using female Wistar rats to study the protective effect of alpha-tocopherol against the tissular necrosis produced by 0.05 mg of doxorubicin hydrochloride. alpha-Tocopherol was administered by two vehicles, one emulsified and the other gelled, with butylated hydroxytoluene and ascorbic acid used as antioxidants, respectively. No differences were observed in the diameters of the ulcers with each treatment in the various groups of animals relative to the control group. Conversely, differences were found (p < 0.05) in the period of chronic lesion between the animals treated with alpha-tocopherol and those used as a control group, irrespective of the vehicle used. These results lead to the conclusion that accidental toxicity resulting from the leakage of doxorubicin hydrochloride in the skin can be mitigated by applying alpha-tocopherol topically, due to its regenerating action in the damaged cutaneous zones. This effect is independent of the vehicle used and also of the antioxidant employed in the elaboration of the formulas.

Animals↗
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↗
PubMedDate not supplied

Modified doxorubicin for improved encapsulation in PVA polymeric micelles.

Polyvinylalcohol, partially substituted with lipophilic acyl chains, generates polymeric micelles in aqueous phase, containing a hydrophobic core able to encapsulate lipophilic drugs. Two types of polymers were obtained by conjugation of polyvinylalcohol with oleoyl or linoleoyl chains as pendant groups. The polymers, at a substitution degree of approximately 1%, are soluble in water and form polymeric micelles whose size increases with polymer concentration. Doxorubicin was hydrophobized, by linking an oleoyl chain via amide bond, to make the drug more similar to the substituted polymers and promote its encapsulation into the inner core of the micelles. The properties of the drug-polymer systems were evaluated in solution by dynamic light scattering technique and correlated to the physicochemical characteristics of the drug and the substituted polymers. Solubilization tests revealed that the similarity of the chain, in both the polymer and the drug, promotes better drug encapsulation in the oleoyl than linoleoyl derivative. The drug-polymer systems are stable in phosphate buffer saline (pH 7.4) at 37 degrees C, and the release of the drug is activated by the presence of the proteolytic enzyme pronase-E. The enzyme activated drug release and the size of the polymeric micelles, compatible with the pore dimensions of the tumor vessels, make these systems interesting for targeting lipophilic drugs to solid tumors, where the proteolytic enzyme concentration strongly raises with respect to the other body compartments.

Doxorubicin↗