Rapid Systemic Elimination Research Articles

Nanoparticle-Formulated Curcumin Prevents Posttherapeutic Disease Reactivation and Reinfection with Mycobacterium tuberculosis following Isoniazid Therapy.

Curcumin, the bioactive component of turmeric also known as “Indian Yellow Gold,” exhibits therapeutic efficacy against several chronic inflammatory and infectious diseases. Even though considered as a wonder drug pertaining to a myriad of reported benefits, the translational potential of curcumin is limited by its low systemic bioavailability due to its poor intestinal absorption, rapid metabolism, and rapid systemic elimination. Therefore, the translational potential of this compound is specifically challenged by bioavailability issues, and several laboratories are making efforts to improve its bioavailability. We developed a simple one-step process to generate curcumin nanoparticles of ~200 nm in size, which yielded a fivefold enhanced bioavailability in mice over regular curcumin. Curcumin nanoparticles drastically reduced hepatotoxicity induced by antitubercular antibiotics during treatment in mice. Most interestingly, co-treatment of nanoparticle-formulated curcumin along with antitubercular antibiotics dramatically reduced the risk for disease reactivation and reinfection, which is the major shortfall of current antibiotic treatment adopted by Directly Observed Treatment Short-course. Furthermore, nanoparticle-formulated curcumin significantly reduced the time needed for antibiotic therapy to obtain sterile immunity, thereby reducing the possibility of generating drug-resistant variants of the organisms. Therefore, adjunct therapy of nano-formulated curcumin with enhanced bioavailability may be beneficial to treatment of tuberculosis and possibly other diseases.

Nano-formulated curcumin accelerates acute wound healing through Dkk-1-mediated fibroblast mobilization and MCP-1-mediated anti-inflammation

Turmeric, a product of Curcuma longa, has a very long history of being used for the treatment of wounds in many Asian countries. Curcumin, the principal curcuminoid of turmeric, has recently been identified as a main mediator of turmeric’s medicinal properties. However, the inherent limitations of the compound itself, such as hydrophobicity, instability, poor absorption and rapid systemic elimination, pose big hurdles for translation to wider clinical application. We present here an approach for engineering curcumin/gelatin-blended nanofibrous mats (NMs) by electrospinning to adequately enhance the bioavailability of the hydrophobic curcumin for wound repair. Curcumin was successfully formulated as an amorphous nanosolid dispersion and favorably released from gelatin-based biomimetic NMs that could be easily applied topically to experimental wounds. We show synergistic signaling by the released curcumin during the healing process: (i) mobilization of wound site fibroblasts by activating the Wnt signaling pathway, partly mediated through Dickkopf-related protein-1, and (ii) persistent inhibition of the inflammatory response through decreased expression of monocyte chemoattractant protein-1 by fibroblasts. With a combination of these effects, the curcumin/gelatin-blended NMs enhanced the regenerative process in a rat model of acute wounds, providing a method for translating this ancient medicine for use in modern wound therapy.

Therapeutic Potential of Novel Nano-Based Curcumin Compounds In Vitro and In Vivo

Despite recent advances in cancer medication, malignant tumors continue to be the second leading cause of death worldwide. Furthermore, introducing a therapeutic compound with low-side effects as well as low-price for consumers is controversial. Recent efforts have been focusing on traditional medicines as a rich source of herbal agents. Curcumin, the major turmeric phytochemical, has been widely assessed as an anti-cancer compound in vitro and in vivo. However, the use of curcumin in cancer treatment has limitations because of its low solubility, poor tissue absorption, rapid metabolism and rapid systemic elimination. Recent work has focused on improving the stability of curcumin to facilitate clinical application. Dendrosomal nano-corcumin (DNC) is one of the most successful compounds showing significant cellular absorption and also anti-tumor effects. The present overview of newest applicable strategies for curcumin-based therapy and their clinical potential usefulness has the emphasis on DNC.

Curcumin-primed and curcumin-loaded exosomes: potential neural therapy.

Curcumin-primed and curcumin-loaded exosomes: potential neural therapy.

Curcumin Encapsulated into Methoxy Poly(Ethylene Glycol) Poly(ε-Caprolactone) Nanoparticles Increases Cellular Uptake and Neuroprotective Effect in Glioma Cells.

Curcumin is a natural polyphenolic compound isolated from turmeric (Curcuma longa) with well-demonstrated neuroprotective and anticancer activities. Although curcumin is safe even at high doses in humans, it exhibits poor bioavailability, mainly due to poor absorption, fast metabolism, and rapid systemic elimination. To overcome these issues, several approaches, such as nanoparticle-mediated targeted delivery, have been undertaken with different degrees of success. The present study was conducted to compare the neuroprotective effect of curcumin encapsulated in poly(ε-caprolactone) and methoxy poly(ethylene glycol) poly(ε-caprolactone) nanoparticles in U251 glioblastoma cells. Prepared nanoparticles were physically characterized by laser doppler anemometry, transmission electron microscopy, and X-ray diffraction. The results from laser doppler anemometry confirmed that the size of poly(ε-caprolactone) and poly(ethylene glycol) poly(ε-caprolactone) nanoparticles ranged between 200-240 nm for poly(ε-caprolactone) nanoparticles and 30-70 nm for poly(ethylene glycol) poly(ε-caprolactone) nanoparticles, and transmission electron microscopy images revealed their spherical shape. Treatment of U251 glioma cells and zebrafish embryos with poly(ε-caprolactone) and poly(ethylene glycol) poly(ε-caprolactone) nanoparticles loaded with curcumin revealed efficient cellular uptake. The cellular uptake of poly(ethylene glycol) poly(ε-caprolactone) nanoparticles was higher in comparison to poly(ε-caprolactone) nanoparticles. Moreover, poly(ethylene glycol) poly(ε-caprolactone) di-block copolymer-loaded curcumin nanoparticles were able to protect the glioma cells against tBHP induced-oxidative damage better than free curcumin. Together, our results show that curcumin-loaded poly(ethylene glycol) poly(ε-caprolactone) di-block copolymer nanoparticles possess significantly stronger neuroprotective effect in U251 human glioma cells compared to free curcumin and curcumin-loaded poly(ε-caprolactone) nanoparticles.

Association of colorectal cancer with pathogenicEscherichia coli: Focus on mechanisms using optical imaging

To investigate the molecular or cellular mechanisms related to the infection of epithelial colonic mucosa by pks-positive Escherichia coli (E. coli) using optical imaging. We choose to evaluate the tumor metabolic activity using a fluorodeoxyglucose analogue as 2-deoxyglucosone fluorescent probes and to correlate it with tumoral volume (mm(3)). Inflammation measuring myeloperoxidase (MPO) activity and reactive oxygen species production was monitored by a bioluminescent (BLI) inflammation probe and related to histological examination and MPO levels by enzyme-linked immunosorbent assay (ELISA) on tumor specimens. The detection and quantitation of these two signals were validated on a xenograft model of human colon adenocarcinoma epithelial cells (HCT116) in nude mice infected with a pks-positive E. coli. The inflammatory BLI signal was validated intra-digestively in the colitis-CEABAC10 DSS models, which mimicked Crohn's disease. Using a 2-deoxyglucosone fluorescent probe, we observed a high and specific HCT116 tumor uptake in correlation with tumoral volume (P = 0.0036). Using the inflammation probe targeting MPO, we detected a rapid systemic elimination and a significant increase of the BLI signal in the pks-positive E. coli-infected HCT116 xenograft group (P < 0.005). ELISA confirmed that MPO levels were significantly higher (1556 ± 313.6 vs 234.6 ± 121.6 ng/mL P = 0.001) in xenografts infected with the pathogenic E. coli strain. Moreover, histological examination of tumor samples confirmed massive infiltration of pks-positive E. coli-infected HCT116 tumors by inflammatory cells compared to the uninfected group. These data showed that infection with the pathogenic E. coli strain enhanced inflammation and ROS production in tumors before tumor growth. Moreover, we demonstrated that the intra-digestive monitoring of inflammation is feasible in a reference colitis murine model (CEABAC10/DSS). Using BLI and fluorescence optical imaging, we provided tools to better understand host-pathogen interactions at the early stage of disease, such as inflammatory bowel disease and colorectal cancer.

Synthesis and anticervical cancer activity of novel pH responsive micelles for oral curcumin delivery

Curcumin (CM) has demonstrated safety and efficacy as a drug, but its pharmaceutical role is restricted as a result of extremely low aqueous solubility, rapid systemic elimination, inadequate tissue absorption and degradation at alkaline pH; properties that severely curtail its bioavailability. To address this issue, CM was encapsulated within pH responsive amphiphilic chitosan, resulting in the formation of 100nm spontaneously self-assembled polymeric micelles in water. The amphiphilic chitosan, namely N-benzyl-N,O-succinyl chitosan (BSCS), was prepared by reductive N-benzylation and N,O-succinylation. The stability of micelles after being re-dispersed in water was investigated using glycine as a cryoprotectant, and the average sizes were shown to be maintained at a level lower than 200nm for up to 4 months, at temperatures of 4°C and 25°C. In vitro drug release results showed that CM was slowly released from the micelles without any burst effect in the intestine (pH 5.5–7.4), with limited release in the stomach (pH 1.2). Cytotoxicity assays indicated that CM loaded micelles showed half maximal inhibitory concentrations (IC50) 4.7-, 3.6-, and 12.2-fold lower than that of free CM in HeLa, SiHa and C33a cervical cell lines, respectively. Cellular uptake of micelles was confirmed by confocal laser scanning microscopy and flow cytometry, with a 6-fold significant increase in the amount of CM loaded micelles compared to free CM in all cervical cancer cells. Notably, CM loaded micelles promoted an increase (30–55%) in the percentage of early apoptosis of HeLa, SiHa and C33a cells, compared to free CM. These results suggest that BSCS micelles may be a promising carrier for effective oral delivery of CM.

Prolonged blood circulation and enhanced tumor accumulation of folate-targeted dendrimer-polymer hybrid nanoparticles

Nanoparticle (NP)-based drug delivery platforms have received a great deal of attention over the past two decades for their potential in targeted cancer therapies. Despite the promises, passive targeting approaches utilizing relatively larger NPs (typically 50–200nm in diameter) allow for passive tumor accumulation, but hinder efficient intratumoral penetration. Conversely, smaller, actively targeted NPs (<20nm in diameter) penetrate well into the tumor mass, but are limited by their rapid systemic elimination. To overcome these limitations, we have designed a multi-scale hybrid NP platform that loads smaller poly(amidoamine) (PAMAM) dendrimers (~5nm in diameter) into larger poly(ethylene glycol)-b-poly(D,L-lactide) (PEG–PLA) NPs (~70nm). A biodistribution study in healthy mice revealed that the hybrid NPs circulated longer than free dendrimers and were mostly cleared by macrophages in the liver and spleen, similar to the in vivo behavior of PEG–PLA NPs. When injected intravenously into the BALB/c athymic nude mice bearing folate receptor (FR)-overexpressing KB xenograft, the targeted hybrid NPs encapsulating folate (FA)-targeted dendrimers achieved longer plasma circulation than free dendrimers and higher tumor concentrations than both free dendrimers and the empty PEG–PLA NPs. These results suggest that the hybrid NPs successfully combine the in vivo advantages of dendrimers and polymeric NPs, demonstrating their potential as a new, modular platform for drug delivery.

Comparative absorption of curcumin formulations

BackgroundThe potential health benefits of curcumin are limited by its poor solubility, low absorption from the gut, rapid metabolism and rapid systemic elimination. The purpose of this study was the comparative measurement of the increases in levels of curcuminoids (curcumin, demethoxycurcumin, bisdemethoxycurcumin) and the metabolite tetrahydrocurcumin after oral administration of three different curcumin formulations in comparison to unformulated standard.MethodsThe relative absorption of a curcumin phytosome formulation (CP), a formulation with volatile oils of turmeric rhizome (CTR) and a formulation of curcumin with a combination of hydrophilic carrier, cellulosic derivatives and natural antioxidants (CHC) in comparison to a standardized curcumin mixture (CS) was investigated in a randomized, double-blind, crossover human study in healthy volunteers. Samples were analyzed by HPLC-MS/MS.ResultsTotal curcuminoids appearance in the blood was 1.3-fold higher for CTR and 7.9-fold higher for CP in comparison to unformulated CS. CHC showed a 45.9-fold higher absorption over CS and significantly improved absorption over CP (5.8-fold) and CTR (34.9-fold, all p < 0.001).ConclusionA formulation of curcumin with a combination of hydrophilic carrier, cellulosic derivatives and natural antioxidants significantly increases curcuminoid appearance in the blood in comparison to unformulated standard curcumin CS, CTR and CP.

The effect of the neonatal Fc receptor on human IgG biodistribution in mice

The neonatal Fc receptor (FcRn) plays a pivotal role in IgG homeostasis, i.e., it salvages IgG antibodies from lysosomal degradation following fluid-phase pinocytosis, thus preventing rapid systemic elimination of IgG. Recombinant therapeutic antibodies are typically composed of human or humanized sequences, and their biodistribution, or tissue distribution, is often studied in murine models, although, the effect of FcRn on tissue distribution of human IgG in rodents has not been investigated. In this report, an 125I-labeled human IgG1 antibody was studied in both wild type C57BL/6 (WT) and FcRn knockout (KO) mice. Total radioactivity in both plasma and tissues (0–96hr post-dose) was measured by gamma-counting. Plasma exposure of human IgG1 were significantly lower in FcRn KO mice, which is consistent with the primary function of FcRn. Differences in biodistribution of human IgG to selected tissues were also observed. Among the tissue examined, the fat, skin and muscle showed a decrease in tissue-to-blood (T/B) exposure ratio of human IgG1 in FcRn KO mice comparing to the WT mice, while the liver, spleen, kidney, and lung showed an increase in the T/B exposure ratio in FcRn KO mice. A time-dependent change in the T/B ratios of human IgG1 was also observed for many tissues in FcRn KO mice. These results suggest that, in addition to its role in IgG elimination, FcRn may also play a role in antibody biodistribution.

Nanotechnology-applied curcumin for different diseases therapy.

Curcumin is a lipophilic molecule with an active ingredient in the herbal remedy and dietary spice turmeric. It is used by different folks for treatment of many diseases. Recent studies have discussed poor bioavailability of curcumin because of poor absorption, rapid metabolism, and rapid systemic elimination. Nanotechnology is an emerging field that is potentially changing the way we can treat diseases through drug delivery with curcumin. The recent investigations established several approaches to improve the bioavailability, to increase the plasma concentration, and to enhance the cellular permeability processes of curcumin. Several types of nanoparticles have been found to be suitable for the encapsulation or loading of curcumin to improve its therapeutic effects in different diseases. Nanoparticles such as liposomes, polymeric nanoparticles, micelles, nanogels, niosomes, cyclodextrins, dendrimers, silvers, and solid lipids are emerging as one of the useful alternatives that have been shown to deliver therapeutic concentrations of curcumin. This review shows that curcumin's therapeutic effects may increase to some extent in the presence of nanotechnology. The presented board of evidence focuses on the valuable special effects of curcumin on different diseases and candidates it for future clinical studies in the realm of these diseases.

APPLICATION OF 23 FULL-FACTORIAL DESIGN FOR DEVELOPMENT AND OPTIMIZATION OF BIOCOMPATIBLE, BIODEGRADABLE SOLID LIPID NANOPARTICLES CONTAINING CURCUMIN

Curcumin (C), a natural anticancer agent suffers extremely low aqueous solubility and rapid systemic elimination, therefore, the aim from the present study was to develop and optimize biocompatible, biodegradable solid lipid nanoparticles containing curcumin (CSLNs) using Solvent Injection Method. The components selected to develop the SLNs were Glycerol MonoStearate (GMS; the lipidic carrier), Poloxamer 407 (P407; Surfactant) and Ethanol (solvent for the drug and the lipidic carrier). The combination and ratios for the optimization process were carried out using 23 full-factorial designs. The experimental design runs (8 formulations H1–H8) were prepared and the design dependent responses (assessment of particle size, Entrapment Efficiency % and the in vitro release study) were characterized. The developed formulae showed a nanometric particle size range (203.0–345.0nm), high Entrapment Efficiency % (62.77–87.42 %) and prolonged release over 24 hr periods (55.97–89.64 %). These results were analyzed using JMP® 10 software and its analytical tools were used to draw Pareto charts and the interactions plots. On the basis of the software analysis, formulation H9 with a desirability factor of 0.582 was selected as the optimized formulation and was evaluated for the dependent responses. Formulation H9 showed a particle size of 249.1 nm, 74.51 % Entrapment efficiency, 85.72 % in vitro release over 24 hr and these results suggested that the solid lipid nanoparticles formulations could be a promising method to sustain the release of curcumin.

Promising Curcumin-based Drug Design: Mono-carbonyl Analogues of Curcumin (MACs)

Curcumin exhibits a surprisingly wide range of chemo-preventive and chemo-therapeutic activities. Curcumin has undergone more than 40 clinical trials for the treatment of inflammatory diseases and various human cancers. However, phase I/II clinical trials have shown that curcumin exhibit poor bioavailability in humans. Major reasons resulting in the low plasma and tissue levels of curcumin appear to be its poor absorption, fast metabolism, and rapid systemic elimination. It is suggested that the β-diketone moiety is responsible for the instability and weak pharmacokinetic profiles of curcumin. To attenuate the fast metabolism of curcumin, numerous approaches have been considered, including the adjuvant, the liposomal curcumin, curcumin nanoparticles and phospholipid complex, and structural modification to prepare the analogues without the β-diketone moiety. Particularly, the latter called mono-carbonyl analogs of curcumin (MACs) has been reported to has an enhanced stability in vitro and an improved pharmacokinetic profile in vivo. Thus, MACs have attracted a high attention for development of new curcumin-based agents with both enhanced bioactivities and pharmacokinetic profiles. A number of MACs have shown potential anticancer and anti-inflammatory activity in various models. Several of them have been studied intensively in order to develop novel agents. This review covers 607 MACs as well as their biological activities reported in the past two decades.

Ciclesonide - A Novel Corticosteroid for the Management of Asthma

Ciclesonide (CIC) is a novel inhaled corticosteroid (ICS) approved by US Food and Drug Administration for the treatment of persistent asthma, available as a pressurized metered-dose inhaler in two strengths, 80 mcg/activation and 160 mcg/activation. Ciclesonide is a corticosteroid with unique pharmacological profile including a high degree of serum protein binding, a low oral bioavailability and rapid systemic elimination. Ciclesonide is a prodrug metabolized by esterases to desisobutyryl ciclesonide (des-CIC), an active metabolite with a 100-fold greater affinity for the glucocorticoid receptor. It has shown to improve pulmonary functions, reduce the need for oral corticosteroids (OCSs) and cause lesser suppression of the hypothalamic-pituitary-adrenal axis in asthmatic patients. Clinical efficacy studies suggest that Ciclesonide is superior to placebo and is at least as effective as several active comparators with an improved therapeutic margin thereby improving the therapeutic outcome in patients of asthma.

Bioavailability of Curcumin: Problems and Promises

Curcumin, a polyphenolic compound derived from dietary spice turmeric, possesses diverse pharmacologic effects including anti-inflammatory, antioxidant, antiproliferative and antiangiogenic activities. Phase I clinical trials have shown that curcumin is safe even at high doses (12 g/day) in humans but exhibit poor bioavailability. Major reasons contributing to the low plasma and tissue levels of curcumin appear to be due to poor absorption, rapid metabolism, and rapid systemic elimination. To improve the bioavailability of curcumin, numerous approaches have been undertaken. These approaches involve, first, the use of adjuvant like piperine that interferes with glucuronidation; second, the use of liposomal curcumin; third, curcumin nanoparticles; fourth, the use of curcumin phospholipid complex; and fifth, the use of structural analogues of curcumin (e.g., EF-24). The latter has been reported to have a rapid absorption with a peak plasma half-life. Despite the lower bioavailability, therapeutic efficacy of curcumin against various human diseases, including cancer, cardiovascular diseases, diabetes, arthritis, neurological diseases and Crohn's disease, has been documented. Enhanced bioavailability of curcumin in the near future is likely to bring this promising natural product to the forefront of therapeutic agents for treatment of human disease.

Characterization of the Hepatic Disposition of Lanoteplase, a Rationally Designed Variant of Tissue Plasminogen Activator in Rodents

Lanoteplase is a recombinant mutant of tissue-type plasminogen activator (t-PA) that was developed with an aim to overcome the drawback of rapid systemic elimination of t-PA. In this study, we examined the disposition profile of lanoteplase in vivo and the kinetics of receptor-mediated endocytosis (RME) of this recombinant t-PA in vitro to kinetically characterize the mechanism(s) underlying its tissue distribution and elimination. Integration plot analysis of the initial-phase tissue distribution in rats revealed a much lower uptake clearance (CL(uptake)) of lanoteplase in the liver than that of t-PA. Rate constants for cell surface binding, internalization, and degradation of lanoteplase were also lower than those for t-PA in primary cultured rat hepatocytes. These results suggest that the improved stability of lanoteplase in vivo could be accounted for by the delay in the RME of this recombinant protein. The CL(uptake) in the liver decreased with coadministration of lactoferrin, a ligand for the low-density lipoprotein receptor-related protein (LRP) and the asialoglycoprotein (ASGP) receptors in normal mice, and in lrpap1((-/-)) mice, which have a hereditary deficiency of LRP; In contrast, CL(uptake) was not affected by mannose, whereas that of t-PA decreased with both ligands and in the lrpap1((-/-)) mice. Thus, the hepatic disposition of lanoteplase seems to be mediated by common specific receptors for t-PA, including LRP and the ASGP receptors, whereas the mannose receptor seems to be only minimally involved in the disposition of lanoteplase.

Effects of Remifentanil and Fentanyl on Postoperative Nausea and Vomiting in Laparoscopic Cholecystectomy with using Propofol

Background: Opioids can produce postoperative nausea and vomiting (PONV). Remifentanil is a nonaccumulative ultra short-acting opioid because of its rapid systemic elimination. This rapid systemic elimination could contribute to a faster weaning from the opioid side-effects like PONV. This study compared remifentanil and fentanyl with regards to the frequency of PONV in laparoscopic cholecystectomy with using propofol. Methods: Sixty ASA physical status I or II patients who were scheduled for laparoscopic cholecystectomy were randomly assigned to either the remifentanil group (n = 30) or the fentanyl group (n = 30). Anesthesia was induced with propofol, rocuronium and remifentanil (n = 30, 1/kg) or fentanyl (n = 30, 2/kg). After tracheal intubation, anesthesia was maintained with propofol, oxygen/air and infusion of opioid (only for remifentanil group 0.2-0.5/kg/min). Postoperatively (1 hr, 12 hr, and 24 hr), we recorded the visual analogue scale (VAS), the rescue meperidine consumption, the number of patients with episodes of PONV and the number of ondansetron injection. Results: The number of PONV episodes were significantly higher in the fentanyl group at the 1-12 hr postoperative period (p ＜ 0.05; n = 8 vs. n = 1, fentanyl and remifentanil, respectively). However, the incidence of PONV at 0-1 hr and 12-24 hr and the total incidence of PONV were not different between the two groups. Conclusions: The use of ultra-short acting remifentanil instead of fentanyl can reduce PONV at 1-12 postoperative hours in the laparoscopic cholecystectomy patients.

Clinical Pharmacokinetics and Drug Metabolism of Tazarotene

Tazarotene (AGN 190168) is a new acetylenic retinoid which is effective for the topical treatment of patients with stable plaque psoriasis and mild to moderate acne vulgaris. Topical gel application provides direct delivery of tazarotene into the skin. At 10 hours after a topical application of 0.1% tazarotene gel to the skin of healthy individuals and patients with psoriasis, approximately 4 to 6% of the dose resided in the stratum corneum and 2% of the dose distributed to the viable epidermis and dermis. Tazarotene is rapidly hydrolysed by esterases to its active metabolite, tazarotenic acid. Tazarotenic acid does not accumulate in adipose tissue, but undergoes further metabolism to its sulfoxide and to other polar metabolites and is rapidly eliminated via both urinary and faecal pathways with a terminal half-life of about 18 hours. Percutaneous absorption is similar between healthy individuals and patients with facial acne, leading to plasma concentrations below 1 microg/L. The systemic bioavailability of tazarotene (measured as tazarotenic acid) is low, approximately 1% after single and multiple topical applications to healthy skin. In patients with psoriasis under typical conditions of use, systemic bioavailability increased during the initial 2 weeks of treatment from 1% (single dose) to 5% or less (steady state). The increased bioavailability is probably related to decreases in plaque elevation and scaling due to successful treatment, resulting in a less effective skin penetration barrier to tazarotene. Steady-state concentrations of tazarotenic acid are achieved within 2 weeks of topical treatment in both healthy and psoriatic skin types. The large variability in plasma concentrations observed in patients with psoriasis is probably because of the large differences in lesional skin condition, the amount of drug applied and the surface area of application. There was no significant drug accumulation in the body with long term treatment of patients with psoriasis. Topical administration of tazarotene requires dosages much smaller than those usually required for oral retinoids, such as isotretinoin, acitretin and etretinate, and it delivers the drug directly into the target skin tissues. The low systemic absorption and rapid systemic elimination of tazarotene and tazarotenic acid results in limited systemic exposure. Thus, topical tazarotene has a low potential for systemic adverse effects and is effective in the treatment of patients with acne and psoriasis.

Liposomal pulmonary drug delivery I.In vivodisposition of atropine base in solution and liposomal form following endotracheal instillation to the rabbit lung

The potential of liposomes as carriers for local pulmonary drug delivery was investigated in the rabbit. Atropine base, a model compound for lipophilic drugs, was encapsulated in neutral MLVs and sprayed at the bifurcation of the trachea. Drug concentrations determined in the lung indicated liposomal encapsulation provided higher drug concentrations within pulmonary tissue for a more prolonged period of time as compared to the solution form. Comparison of drug levels in plasma and appearance of drug in urine demonstrated more rapid systemic absorption and elimination of 'free' drug. Greater accessibility of drug in solution to the systemic circulation was reflected in higher atropine concentrations in all internal organs studied. Liposome encapsulation favourably altered the disposition of atropine base when locally administered to the rabbit lung.