Effectiveness and safety of iodopovidone in an experimental pleurodesis model

Comparison of Hydroxyethyl starch 130/0.4 (6%) with commonly used agents in an experimental Pleurodesis model

Background

Hydroxyethyl Starch (HES) 130/0.4 (6%) is a commonly used intravascular volume expander with anti-inflammatory and antioxidant properties. In this study, we aimed to compare the histopathologic activity of HES 130/0.4 (6%) with various widely-used agents in pleurodesis.

Methods

Forty male Wistar-Albino rats were divided into five groups: controls, povidone-iodine recipients (PI group), sterile talcum recipients (Talcum group), autologous blood recipients (AB group) and HES 130/0.4 (6%) recipients (HES group). Thirty days after application of agents, pleural and lung tissues were resected. Evaluation was performed via macroscopic scoring (adhesion) and specimens were stained with H&E for microscopic examination (inflammation and fibrosis).

Results

HES recipients had significantly higher adhesion compared to controls (lower grade 0, higher grade 1 frequency vs. controls), they were found to have significantly lower frequency of grade 2 adhesion (vs. PI, Talc and AB) and grade 3 adhesion (vs. AB), indicating that the adhesion-generating properties of HES were only superior to the control group. HES recipients had significantly higher inflammatory grades compared to controls (lower grade 0, higher grade 1 frequency), while they had lower grades compared to the PI, Talc and AB groups. Although the PI, Talc and AB groups were statistically similar in most comparisons, we observed a trend towards higher success with the use of Talc and especially AB.

Conclusion

Our results do not support a role for HES in pleurodesis. We believe that the autologous blood method remains as an effective and successful procedure without side effects.

Influence of the progression of pleural neoplasia on the outcome of pleurodesis in mice

Purpose: Experimental study aimed at evaluating whether pleural neoplastic disease is associated with the degree of pleural fibrosis over time caused by talc pleurodesis. The study describes changes in levels of inflammatory mediators and determines whether the course of time involved in progression of neoplastic pleural disease is the factor that influences safety of talc pleurodesis usage in mice.

Materials and Methods: Animals were randomized into two groups: Cancer group (CG) that received intrapleural injection of Lewis cells or Saline group (SG) that received saline injection. After, the animals were subdivided into Early (pleurodesis 3 days after pleural injection) and Late (pleurodesis 7 days after pleural injection) groups. Half of the animals in each group were euthanized 24 hours after pleurodesis (to obtain the inflammatory data); the remaining animals were killed after 8 days (to obtain the scores of pleural fibrosis).

Results: CGs had lower fibrosis scores than SGs comparing early phases to late phases. Inflammation scores were lower in CGs, particularly in Late group. In SGs the inflammation was intense in 100% of the animals.

In Late CG group pleural adhesions had the lowest scores; we found intense fibrosis only in SGs. VEGF and LDH levels had increased in animals with cancer, particularly in Late group. Systemic distribution of talc occurred only in Late CG.

Conclusions: The time for pleural neoplasia to evolve is inversely proportional to the degree of pleural fibrosis. Earlier pleurodesis yielded the best results related to fibrosis, with less systemic inflammation and is safer in mice.

Subchronic Toxicity of the New Iodine Complex in Dogs and Rats

Background: Complexes of iodine (povidone-iodine and cadexomers) are among the most important antiseptics used in clinical and veterinary medicines. However, high local irritation activity and systemic toxicity limits their oral administration. The purpose of the study was to compare the effect of a new complex of iodine (PA, potentiator of anticancer antibiotics), in which iodine is coordinated by carbohydrates and polypeptides) on the organisms of rats and dogs treated orally with the drug for 30 days. Methods: Wistar rats and Beagle dogs served as experimental animal models. Effect of PA on the animal organism was examined through the measurements of hormones level changes, hematological and clinical chemistry parameters alterations, necropsy and histological examination. Results: The established maximum tolerated dose (MTD) of 2,000 mg/kg PA led to a decrease in the rate of body weight gain in male and female rats. Changes in hematological and certain biochemical parameters in rats at doses of 1,000 and 2,000 mg/kg were observed. Histological study of the thyroid gland revealed changes in the shape and size of the follicles along with colloid resorption. Administration of a half of MTD (180 mg/kg) and lower doses did not result in any change in dogs (thyroid-stimulating hormone, triiodothyronine, and thyroxine). Conclusions: The results of our study show that the pathogenetic action of PA takes place along the path of induction of an inflammatory response with the development of thyrotoxicosis, rather than hypothyroidism. The mechanism of induction of an inflammatory response is also confirmed by histological studies of lesions of the thyroid gland and testes in rats (Figure S1). The no-observed-adverse-effect level (NOAEL) of PA is estimated to be 180 mg/kg (or iodine 22.8 mg/kg) in dogs, which is equivalent to 100 mg/kg (or iodine 12.3 mg/kg) in humans.

The efficacy of hydrogel foams in talc Pleurodesis

BACKGROUND

Malignant pleural effusions are a serious complication of many late stage cancers that adversely affect quality of life. Pleurodesis with talc slurry is a standard treatment option, but clinical failures occur, possible due to poor talc delivery. A novel drug-delivery system was developed that fills the entire thoracic cavity with a liquid foam containing talc. The foam is designed to gel and adhere to the tissue walls at body temperature, to improve talc deposition and efficacy.

METHODS

Rheology, foam stability, and ex-vivo coating and bio-adhesion studies were performed on three concentrations of a novel hydrogel talc foam system that was developed to improve delivery of talc to the pleural surfaces. A New Zealand rabbit model of pleurodesis was used to evaluate effectiveness of the foams at inducing adhesion formation and compared to talc slurry. The rabbits were recovered after they had one of the test agents instilled into their pleura, and then sacrificed after 28 days. Pleurodesis was assessed by a blinded pathologist using a standardized pathological scoring system.

RESULTS

All talc foam formulations produced foams that gelled at physiological temperatures and were relatively stable for at least two hours. As the concentration of the formulation increased the gelation temperature decreased and the foam adhesiveness increased. Rabbits that received talc foam had significantly greater adhesion formation than talc slurry (mean score of 2.21 vs. 1.18 (p < 0.05)). Rabbits that received the 20% foam developed the most adhesions.

CONCLUSIONS

This study demonstrates that our triblock copolymer hydrogel foam delivery system enhances adhesion formation in an experimental model. This novel approach can have important clinical impact, potentially improving efficacy of existing therapies and reducing the need for more invasive treatments.

Chemical pleurodesis - a review of mechanisms involved in pleural space obliteration

Chemical pleurodesis is a therapeutic procedure applied to create the symphysis between the parietal and visceral pleura by intrapleural administration of various chemical agents (e.g. talk, tetracycline, iodopovidone, etc.). The two major clinical conditions treated with chemical pleurodesis are recurrent pleural effusion (PE) and recurrent spontaneous pneumothorax. Although the history of chemical pleurodesis began over a century ago, detailed data on the mechanisms of action of sclerosing agents are highly incomplete. The following article aims to present the state of knowledge on this subject.It is believed that mesothelial cells are the main structural axis of pleurodesis. In response to sclerosing agents they secrete a variety of mediators including chemokines such as interleukin 8 (IL-8) and monocyte chemoattractant protein (MCP-1), as well as growth factors - vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and transforming growth factor- β (TGF-β). Numerous data suggest that intact mesothelial cells and the above cytokines play a crucial role in the initiation and maintenance of different pathways of pleural inflammation and pleural space obliteration.It seems that the process of pleurodesis is largely nonspecific to the sclerosant and involves the same ultimate pathways including activation of pleural cells, coagulation cascade, fibrin chain formation, fibroblast proliferation and production of collagen and extracellular matrix components. Of these processes, the coagulation cascade with decreased fibrinolytic activity and increased fibrinogenesis probably plays a pivotal role, at least during the early response to sclerosant administration.A better understanding of various pathways involved in pleurodesis may be a prerequisite for more effective and safe use of various sclerosants and for the development of new, perhaps more personalized therapeutic approaches.

The effect of iodopovidone versus bleomycin in chemical pleurodesis

Background Malignant pleural effusion continues to be a common problem in patients with metastatic disease. This study was conducted to compare the efficacy and safety of bleomycin pleurodesis with povidone-iodine pleurodesis through a chest drain as palliative treatment for recurrent malignant pleural effusion. Methods Sixty cancer patients (36 males and 24 females) with recurrent malignant pleural effusion were enrolled in a prospective randomized trial. Thirty patients received povidone-iodine pleurodesis and 30 received bleomycin pleurodesis. Age, sex, side of the primary pathology, treatment outcome (recurrence and relapse time), and complications were analyzed. Results The mean age was 59.63 ± 7.68 years in the povidone-iodine group and 57.97 ± 9.27 years in the bleomycin group ( p = 0.452). The complications were identical in both groups: 2 (6.7%) patients had chest pain, 2 (6.7%) had fever, and one (3.3%) had hypotension. There was a good response to therapy in 20 (66.7%) patients in the bleomycin group and 25 (83.3%) in the povidone-iodine group ( p = 0.136). Conclusion The results of this study indicate that povidone-iodine should be considered as a selective chemical agent to perform pleurodesis in patients with recurrent malignant pleural effusion because it has the same effect but costs less than bleomycin.

The effects of aqueous extract of babassu (Orbignya phalerata) on the pleura and lung parenchyma in rats

PURPOSE

To evaluate macro and microscopically, changes following the use of the aqueous extract of babassu (Orbignya phalerata) in the lung parenchyma and pleura of rats.

METHODS

Sixty adult male rats with average weight of 350 g, were randomized into two groups of 30 animals (experimental and control) further divided into sub-groups of 10 to be sacrificed at 48 h, 72 h and 21 days. The substance was injected into the right pleura of the animals.

RESULTS

There was intense pleuropulmonary macroscopic reaction with statistically significant differences between groups respectively (p<0.05, p<0.02, p<0.03). Microscopically, no statistically significant difference was evident (p>0.05).

CONCLUSION

The aqueous extract of babassu (Orbignya phalerata) was found to be highly irritating to the pleura and lung of rats, evidenced macroscopically by numerous adhesions and inflammation while no major changes were evident microscopically.