Evaluation of the efficacy of albendazole sulphoxide and praziquantel in combination on Taenia crassiceps cysts: in vitro studies

Albendazole is an anthelmintic drug widely used in the treatment of neurocysticercosis (NCC), an infection of the brain with Taenia N eurocysticercosis (NCC) is a major cause of adult-onset seizures and epilepsy in many areas of the developing world. It is an infection with the larval cyst form of the cestode tapeworm Taenia solium acquired through the accidental ingestion of ova shed in the feces of human tapeworm carriers. The released oncospheres find their way to the bloodstream and are carried throughout the body but develop mostly in the muscles, subcutaneous tissues, and brain. Almost all the symptoms are due to brain involvement (1).Two drugs, the benzimidazole albendazole (ABZ) and the pyrazinoisoquinoline praziquantel (PZQ), are commonly used to treat neurocysticercosis, usually with accompanying immunosuppressive/anti-inflammatory medication (2-4). Albendazole is frequently preferred to praziquantel because it is more widely available, has a lower cost, and normally requires shorter courses of treatment (and hence represents lower hospitalization-associated expenses) for higher efficacy (2, 5-7).In susceptible parasites, the main effect of ABZ is the inhibition of tubulin polymerization into microtubules, but the drug also causes biochemical changes such as inhibition of mitochondrial fumarate reductase, reduced glucose transport, and uncoupling of oxidative phosphorylation, impairing ATP generation (8, 9). Although ABZ has been used since the 1970s (10, 11), it is not completely effective in killing cysts; 12% and 45% of total cysts remain after the usual dosing regimens used with albendazole and praziquantel, respectively (12). Cure rates are unacceptably low for both drugs at about 40% to 50%, so retreatments are often required.After oral administration, the nonchiral ABZ is oxidized in the liver to its active metabolite, albendazole sulfoxide (ABZSO), with one chiral center in the sulfoxide group. The two possible enan- (13), show different pharmacokinetics and affinities for cytosolic proteins from different parasites (28). Kinetic parameters of (ϩ)-(R)-and (Ϫ)-(S)-ABZSO enantiomers in NCC patients treated with ABZ differ in renal excretion (14), accumulation in plasma (15), and, most importantly, distribution in the cerebrospinal fluid (12). Even though the levels of effectiveness of the two enantiomers against a number of other helminths differ, the effect of the isolated enantiomers against T. solium metacestodes (cysts) has not been reported. tiomers, (ϩ)-(R)-and (Ϫ)-(S)-ABZSOA sensitive in vitro system to quantify drug effects on cysts of T. solium has been recently reported (16). In this system, drug sensitivity to both ABZSO and PZQ correlates with the degree of inhibition of alkaline phosphatase (AP) release from cysts, obtained from naturally infected pigs and cultured in vitro (16). Using this system, we compared the anthelmintic effect of the (ϩ)-(R)-and (Ϫ)-(S)-ABZSO enantiomers to effects of the ABZSO racemic mixture and of PZQ. Here we show that the antiparasitic effect of the drug ...

Section: Discussionsupporting

confidence: 87%

In Vitro Analysis of Albendazole Sulfoxide Enantiomers Shows that (+)-( R )-Albendazole Sulfoxide Is the Active Enantiomer against Taenia solium

Paredes

Lourenço

Marzal

et al. 2013

“…Studies using T. solium cysts are difficult because many infected pigs are required, harvesting cysts individually is laborious and time-consuming, and culturing and maintaining cysts in the laboratory is difficult. For these reasons, cysts of a related parasite of the same genus as T. solium, Taenia crassiceps, have been commonly used instead of T. solium cysts for in vitro studies of drug effects and parasite biology (16,17,32). However, it is not known whether any or all of the conclusions from these studies can be applied to T. solium.…”

mentioning

confidence: 99%

“…Traditionally, the effects of drugs on taeniid cysts have been assessed by visual examination of cysts for morphological and histopathological changes on light or electron microscopy suggesting damage (16,17). Although these approaches have demonstrated effects of the commonly used anthelmintics for treatment of T. solium (17) and other cestodes (7, 11), the techniques require experienced personnel and equipment and are time-consuming for routine use and analysis.…”

mentioning

confidence: 99%

Sensitive In Vitro System To Assess Morphological and Biochemical Effects of Praziquantel and Albendazole on Taenia solium Cysts

Mahanty

Paredes

Marzal

et al. 2011

Neurocysticercosis resulting from Taenia solium infections is a major cause of adult-acquired seizures worldwide. Disease is caused by larval cysts, and treatment consists of the anthelmintic drugs albendazole or praziquantel. There are no standard methods to assess drug activity to T. solium cysts in vitro. Morphological, functional, and biochemical changes that might reflect damaging (inhibiting, cytotoxic) drug effects were analyzed after exposure of cysts to albendazole sulfoxide (ABZ-SO), the major active metabolite of the drug in vivo, praziquantel (PZQ), or combinations of both. PZQ exposure led to a decrease in cyst size and inhibition of evagination, whereas ABZ-SO exposure resulted in minimal changes. Alkaline phosphatase (AP) is normally secreted by cysts, and both drugs inhibited AP secretion at concentrations of 5 and 50 ng/ml for PZQ and ABZ-SO, respectively. Some combinations of both drugs resulted in additive and/or synergistic activities. Parasite-specific antigen, detected in the cerebrospinal fluid and blood of infected patients, is also normally secreted by T. solium cysts. Antigen secretion was similarly inhibited by ABZ-SO and PZQ and a combination of both drugs, suggesting that inhibition of secretion is a common downstream consequence of the activities of both drugs. These studies establish quantitative methods to measure in vitro anthelmintic activity and suggest combination therapy with ABZ-SO and PZQ may have clinical benefit. Neurocysticercosis (NCC), the most common cause of adult acquired seizures worldwide, results from infection of the brain by the cystic larval stage of Taenia solium. The adult tapeworm resides in the human intestines. It consists of a head with a scolex, which is an attachment organ, a neck, and increasingly maturing segments containing infectious ova. These are excreted as segments in the feces and, when ingested by freeroaming pigs, hatch and are carried to the brain, muscles, and other organs, where they develop into viable cysts in about 2 to 3 months. After ingestion and exposure to bile and other factors in the gastrointestinal tract milieu, the cysts evaginate and develop into tapeworms. Humans develop NCC after accidental ingestion of infectious ova sometimes originating from their own tapeworm or one residing in a family member or coinhabitant.The clinical manifestations of NCC are due to growth, degeneration, and inflammation associated with the host response to the cyst. Treatment consists of the anthelmintic agents albendazole or praziquantel (PZQ) (4, 5, 15), as well as corticosteroids or other anti-inflammatory agents (4,14), that are commonly used to control treatment-induced inflammation. However, cure rates are relatively low with currently available regimens, and more effective agents are needed.T. solium larval cysts (metacestodes) can only be obtained from infected pigs. Studies using T. solium cysts are difficult because many infected pigs are required, harvesting cysts individually is laborious and time-consuming, and culturing and maintain...

“…The low values precluded the use of OD ratios as a reliable measure of enzyme release. Previous studies, by aggregating the enzyme released over the whole period of culture, avoided this issue and may have thereby allowed detection of ABZSO effects (17,18), although we believe that the rate of accumulation provides additional useful information about the effects of drugs on the parasite.…”

Section: Discussionmentioning

confidence: 99%

Quantitative Screening for Anticestode Drugs Based on Changes in Baseline Enzyme Secretion by Taenia crassiceps

Mahanty

Madrid²,

Nash

2013

Neurocysticercosis (NCC), an infection of the brain with the larval stage of the Taenia solium tapeworm, is responsible for an estimated one-third of adult-onset epilepsy cases in regions of the world where it is endemic. Currently, anthelmintic drugs used for treatment of NCC are only partially effective, and there is, therefore, a pressing need for new therapeutic agents. Discovery of new anthelmintics with activity against T. solium has been limited by the lack of suitable sensitive assays that allow highthroughput screening. Using an in vitro culture system with Taenia crassiceps metacestodes, we demonstrate that changes in secretion of parasite-associated alkaline phosphatase (AP) and phosphoglucose isomerase (PGI) can be used to detect and quantify anthelmintic effects of praziquantel (PZQ), a drug with activity against T. solium. We applied two enzyme release assays to screen for anti-T. crassiceps activity in nonconventional antiparasitic drugs and demonstrate that nitazoxanide and artesunate induced release of both AP and PGI in differing time-and dose-related patterns. Furthermore, imatinib, a tyrosine kinase inhibitor previously reported to have parasiticidal activity against Schistosoma mansoni, also induced release of both AP and PGI in a dose-dependent manner, similar in pattern to that observed with the other anthelmintics. We also evaluated release of ATP into cyst supernatants as an indicator of drug effects but did not see any differences between treated and untreated cysts. These data provide the basis for rapid and quantitative screening assays for testing for anthelmintic activity in candidate anticestode agents.