In vitro and in vivo suppression of growth of hepatocellular carcinoma cells by albendazole

Antitumor activity of albendazole against the human colorectal cancer cell line HT-29: in vitro and in a xenograft model of peritoneal carcinomatosis

The peritoneal surface remains an important failure site for patients with colorectal cancer. We have recently shown that albendazole (ABZ), a safe and effective anthelmintic drug, has profound antitumor activity in hepatocellular cancer. Furthermore, albendazole also possesses unique physiochemical and pharmacokinetic properties probably making it a potential drug for use in the regional treatment of peritoneal carcinomatosis (PC). The current study was therefore designed to investigate this concept under both in vitro and in vivo conditions using human colorectal cancer cells HT-29. In cell culture, studies were conducted to investigate the effect of ABZ and its major metabolites, albendazole sulfoxide (ABZ-SO) and albendazole sulfone (ABZ-SO2) on the growth of human colorectal cell line HT-29. We also investigated the effects of ABZ on the cell cycle and the possible induction of apoptosis in these cells. Male nude mice inoculated intraperitoneally (i.p.) with HT-29 cells were treated with various schedules of ABZ given i.p. or orally for 6 weeks. Response was evaluated as the number of peritoneal tumor nodules present in animals at the end of the treatment period. In vitro, ABZ treatment of cells for 5 days led to profound inhibition of growth. (3)H-Thymidine assay and trypan blue viable cell counts confirmed the dose- and time-dependency of the ABZ effect, while recovery experiments revealed the reversible nature of this inhibition. ABZ-SO and ABZ-SO2 were also evaluated in cell culture studies and compared with the parent drug. In HT-29 cells, the IC(50) values were calculated to be 0.12 microM for ABZ and 2.35 microM for ABZ-SO. The other metabolite, ABZ-SO2, was completely inactive. Studies on the mechanism of ABZ action, revealed arrest of HT-29 cells at the G(2)/M phase of the cell cycle, while TUNEL, DNA laddering and caspase-3 activity all confirmed ABZ induced apoptosis. In nude mice with peritoneal HT-29 xenografts, ABZ profoundly inhibited peritoneal tumor growth. While alternate i.p. dosing (ABZ, 150 mg/kg) led to the highest degree of tumor growth suppression (P<0.001), schedules such as once-weekly dosing and even a single dose for the entire course of treatment (6 weeks) were also effective in reducing peritoneal tumor growth. However, no such activity was observed when ABZ was administered orally. This study shows for the first time the potent effect of regionally administered ABZ in suppressing the growth of peritoneal tumors of human colorectal origin. The effect is thought to be brought about by arresting tumor cells at the G(2)/M phase of the cycle and apoptosis. These findings provide evidence for potential value of ABZ in the treatment of regional PC arising from colorectal cell lines.

Effect of clotrimazole on microsomal metabolism and pharmacokinetics of albendazole

Albendazole is a broad spectrum anthelmintic drug widely used in human and veterinary medicine. Intestinal and hepatic albendazole metabolism leads to albendazole sulfoxide (active metabolite) and albendazole sulfone (inactive metabolite) formation. Microsomal sulfonase activity can be abolished by in-vitro interaction with clotrimazole and pharmacokinetic studies confirm this interaction. After albendazole incubation, albendazole sulfone formation was completely inhibited by 50 microM clotrimazole in intestinal incubations and a 50% inhibition was observed in hepatic incubations. The lower inhibition constant (K(i)) value observed in the intestinal incubations (9.4 +/- 1.0 microM) compared with the hepatic counterparts (23.3 +/- 15.8 microM) pointed to a greater affinity of the enzymatic systems in the intestine. Regarding the formation of albendazole sulfoxide, an inhibition close to 50% was observed in liver and intestine at 10 microM clotrimazole. The pharmacokinetic parameters obtained following the oral co-administration of albendazole sulfoxide and clotrimazole corroborated the in-vitro inhibition of albendazole sulfone formation, since the ratio of the area under the plasma concentration-time curves for the sulfoxide/sulfone (AUC(ABZSO)/AUC(ABZSO2)) was significantly higher (38.1%). In addition, the AUC and C(max) for albendazole sulfone were significantly lower. The effect of clotrimazole was also studied after prolonged treatment. Hepatic microsomal metabolism of albendazole was induced after 10 days of clotrimazole administration, with significant increases in formation of albendazole sulfoxide (40%) and sulfone (27%). These results offer further insight into the metabolism of benzimidazole drugs and highlight the difficulty involved in human therapy with these anthelmintics, since after prolonged treatment the drug interactions are affected differentially.

Effect of amphiphilic surfactant agents on the gastrointestinal absorption of albendazole in cattle

Albendazole (ABZ) is a widely used broad-spectrum benzimidazole (BZD) anthelmintic. Low hydrosolubility and poor/erratic gastrointestinal (GI) absorption play against the systemic availability and resultant clinical efficacy of BZD compounds. Different strategies are currently investigated to improve their bioavailability and efficacy in different animal species and humans. Surfactant agents facilitate dissolution of lipophilic drugs and increase membrane permeability. The influence of amphiphilic surfactants on the pattern of absorption and systemic availability of ABZ and its metabolites in cattle was characterized in the current trial. Twenty (20) parasite-free Holstein calves (100-120 kg) were randomly allocated into four groups and treated intraruminally (10 mg/kg) using one of the following ABZ suspensions: control without surfactant (75/25 dimetyl sulphoxide/saline solution) (group A), 5 mM sodium taurocholate (STC) in saline solution (group B), 8.27 mM sodium lauryl sulphate (SLS) in saline solution (group C) and a commercial formulation (Valbazen((R)), Pfizer Inc. SA) (group D). Jugular blood samples were taken over 72 h post-treatment and plasma analysed by HPLC. Albendazole sulphoxide (ABZSO) and sulphone were the metabolites found in plasma. STC did not affect ABZ absorption while increased ABZSO peak plasma concentration (C(max)) (158% higher, P<0.001) was observed following co-administration of ABZ plus SLS, compared to the control group without surfactant. ABZSO plasma availability was significantly greater after the ABZ-SLS (164%) co-administration compared to that obtained in the control group without surfactant. A similar ABZSO plasma availability was obtained following the treatments with the ABZ-SLS and the commercially available formulation. SLS-mediated enhanced dissolution and absorption of ABZ accounted for the observed increased systemic availability of the active ABZSO metabolite in cattle. These results should be considered among strategies to improve the use of BZD anthelmintics.

Albendazole: a new drug for human parasitoses

In 1961 Brown and his team discovered that thiobendazoles were highly effective against gastrointestinal nematodes. This discovery led to the development of albendazole, the most recent of the benzimidazolic drugs. Albendazole is used against numerous animal and human parasites and it is the authors' first choice as drug treatment of cutaneous larva migrans.

Albendazole: a broad spectrum anthelminthic for treatment of individuals and populations

PURPOSE OF REVIEW

It is over 25 years ago since the original animal research was conducted into albendazole. This review highlights some important steps in fundamental research and the management of helminth disease that have occurred in the past year, appearing in the published literature.

RECENT FINDINGS

In recent years there have been several published studies on lymphatic filariasis and on the impact of albendazole treatment on growth and nutrition. Recent work consolidates some of these data and supplies substantive evidence of benefit especially in the area of hookworm anaemia. Why treatment of helminths actually produces these effects has not been understood, but investigations have begun to highlight the underlying mechanisms that relate to immunity. During the last year several reviews of diagnosis and management of helminth diseases have been published which provide much needed guidance on the effective use of albendazole, and its place in treatment overall. In common with many other parasitic diseases, the validity of using single agents is being challenged, and combination therapy is being investigated at the experimental level and in clinical practice to improve therapeutic responses and to reduce the risk of resistance to the limited range of drugs currently available.

SUMMARY

Albendazole has changed from being a drug for individuals with worms to one to treat communities and provide benefit in public health terms. In systemic parasitic disease, however, albendazole remains a treatment for individuals. Nearly 20 years of research and of clinical use has refined the tool, but new investigations suggest that much additional study is required before we fully understand helminth parasites and the benefits of treating them.