Biomedical subjects

A Gerloczy

Publications and source records attributed to A Gerloczy.

4 recordsLinked to original sources

PubMed2001

Cyclodextrins in oligonucleotide delivery.

The aim of this contribution is to summarize recent findings on the potential use of cyclodextrins and their derivatives as carriers for oligonucleotide agents. Their peculiar properties could be exploited in such an emerging therapeutic area by virtue of their capability of interacting with cellular membranes, thus giving rise to improved cellular uptake. In particular, some specific derivatives could be considered as promising future excipients for the delivery of "naked" antisense and/or decoy oligonucleotides which are difficult to formulate with existing pharmaceutical excipients.

Animals↗

PubMed1995

Safety of parenteral hydroxypropyl beta-cyclodextrin.

Post-treatment data were collected on a patient who received intravenous hydroxypropyl beta-cyclodextrin in a dose of 1.5 g/kg in 1985. Although no untoward effects were observed in this patient, rarely occurring agitation and pulmonary edema have been noted after injections into rabbits and dogs, respectively. These complications are analyzed here on the basis of symptoms and on the effects of hydroxypropyl beta-cyclodextrin on the biochemistry of a representative lipid, cholesterol, which were studied in rats. It is hypothesized that these untoward effects of parenteral hydroxypropyl beta-cyclodextrin are due to complex formation, with lipid mediators of pathological responses, of which prostaglandins are one example. These mediators normally have brief and localized functions; if hydroxypropyl beta-cyclodextrin happens to be injected when these mediator systems are activated, their influence and the responses of the organism may be increased.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed1994

Safety of oral cyclodextrins: effects of hydroxypropyl cyclodextrins, cyclodextrin sulfates and cationic cyclodextrins on steroid balance in rats.

Derivatives of beta-cyclodextrin differing in the length of a hydroxyalkyl substituent (CH2CH2OH, CH2CHOHCH3, CH2CHOHCH2CH2CH2CH3) or in the electrical charge of the substituents (SO4-, CH2CHOHCH2N(CH3)3+) and hydroxypropyl derivatives (CH2CHOHCH3) of alpha-, beta-, and gamma-cyclodextrin were compared, individually and in mixtures, as solubilizers of cholesterol. The most effective solubilizer proved to be hydroxypropyl derivatives of beta-cyclodextrin; beta-cyclodextrin sulfate (SO4-) was practically devoid of solubilizing activity. Oral administration of these cyclodextrin derivatives, some of which are both nondegradable and effective complexation agents for cholesterol and bile acids, nevertheless did not affect the conversion of [14C]acetic acid to [14C]-cholesterol in rat under the same conditions when another bile acid complexation agent, cholestyramine, increased that conversion. Thus, complexation of cholesterol and of bile acids by cyclodextrin derivatives, which is a significant and well-defined phenomenon in vitro, seems to have limited importance in terms of excretion of cholesterol from the gastrointestinal tract. It is proposed that various untoward effects observed after chronic large oral doses of hydroxypropyl beta-cyclodextrin are administered are not caused by an increased excretion of some vital lipophile or enzyme but are probably caused by solubilization and increased absorption of toxic contaminants of the ingested food.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed1994

Parenteral hydroxypropyl cyclodextrins: intravenous and intracerebral administration of lipophiles.

Hydroxypropyl cyclodextrins are nontoxic carbohydrate derivatives of moderate molecular weight (1030-1750 Da) which form water-soluble complexes with many lipophiles. The fate of hydroxypropyl beta-cyclodextrin alone and in complex with testosterone or cholesterol injected intravenously or intracerebrally into rats was followed. More than 90% of intravenously administered hydroxypropyl beta-cyclodextrin was cleared into urine in 4 h, as previously described (Monbaliu, J.; Van Beijsterveld, L.; Meuldermans, W.; Szathmary, S.; Haykants, J. Abstracts, 5th International Symposium on Cyclodextrins, Paris, 1990; Abstract 65). After the injection of steroids in complex with hydroxypropyl beta-cyclodextrin into the tail vein of rats, the steroid component was released from the complex, before it reached the kidneys; the release occurred mainly into the proteins and lipoproteins of serum. Hydroxypropyl beta-cyclodextrins injected alone into the brain were cleared within less than 24 h, presumably via the flow of interstitial and cerebrospinal fluids, and eventually were excreted in urine. Testosterone, incorporated in a hydroxypropyl beta-cyclodextrin complex, after intracerebral injection was cleared from the brain even more rapidly than hydroxypropyl beta-cyclodextrin, presumably by crossing the blood-brain barrier and later removal to the liver by the specific carrier proteins in serum. Complexed cholesterol, in a similar experiment, was largely retained in the brain and its distribution there was uneven and remained that way for at least 3 days. It is clear that lipophilic agents, after their incorporation into hydroxypropyl beta-cyclodextrin complexes and subsequent in vivo administration, are rapidly released and exchanged into the plasma. In absence of plasma they enter tissues surrounding the injection site and thus are also promptly transferred into the organism's lipid systems. The manner in which different lipophilic agents are transported in vivo appears not to be greatly affected by their previous complexation; rather hydroxypropyl cyclodextrins just enable their entry in a larger amount and in an exchangeable, nonaggregated form.

2-Hydroxypropyl-beta-cyclodextrin↗