Interferon signal transduction of biphenyl dimethyl dicarboxylate/amantadine and anti-HBV activity in HepG2 2.2.15

Biphenyl dimethyl dicarboxylate (DDB) is a hepatoprotectant, which is used as an adjuvant agent in a treatment for chronic hepatitis. Amantadine is an antiviral agent, which is utilized primarily in the treatment of influenza, but also, occasionally in the treatment of hepatitis C. In a previous study, we reported that DDB, coupled with amantadine, would exert an anti-HBV effect, via the induction of interferon-inducible gene expression in the HepG2 2.2.15 cell line. The primary objective of the present study was to determine whether or not DDB and/or amantadine exhibit anti-HBV properties, and what mechanisms of action might be involved in such properties. In our study, we were able to determine that DDB stimulates Jak/Stat signaling, and induces the expression of interferon alpha (IFN-alpha) stimulated genes, most notably 6-16 and ISG12. In addition, the antiviral effectors induced by IFN-alpha, PKR, OAS, and MxA, were regulated in the presence of DDB at its optimal concentration (250 microg/mL), to a degree commensurate with the degree of induction associated with the IFN-alpha treated group. Finally, we determined that the replication of pregenomic RNA and HBeAg was inhibited by DDB treatment, and this inhibition was maximized when coupled with the administration of amantadine (25 microg/mL). In conclusion, the results of this study demonstrated clearly that DDB, as well as the combination of DDB/amantadine, directly inhibited IFN-alpha signaling-mediated replication of HBV in infected hepatocytes, and thus may represent a novel treatment for chronic hepatitis B, which would be characterized principally by its improved safety over other treatment strategies.

Toxic effect of single treatment with bromantane on neurological status of experimental animals

Neurotoxicological profile of actoprotector bromantane was studied on rats using S. Irwin's protocol of multi-test observation. The drug in doses of 30-300 mg/kg stimulated and in doses of 600-9,600 mg/kg suppressed behavioral activity. Spontaneous motor activity increased after single treatment with bromantane in doses of 30-300 mg/kg, did not change after treatment in doses of 600 mg/kg, and was inhibited after treatment in doses above 600 mg/kg. In doses of 300-600 mg/kg the drug reduced pain sensitivity threshold and in doses above 600 mg/kg elevated the pain threshold and tactile sensitivity and reaction to knock. Bromantane induced mydriasis in all studied doses; in doses above 10 g/kg the preparation induced blepharoptosis. In doses above 5 g/kg bromantane slightly increased respiration rate and depth (Kussmaul-like respiration). In some animals bromantane in high doses induced regurgitation, diarrhea, and polyuria. Rectal temperature decreased by 0.5-1 degrees C after virtually all doses. Behavioral effects of bromantane in doses of 30 and 600 mg/kg were associated with stimulation of the central dopamine and suppression of muscarinic and nicotinic cholinergic structures, n-cholinolytic effects of bromantane was more pronounced at a dose of 30 mg/kg than at a dose of 600 mg/kg.

Adamantylamide dipeptide as effective immunoadjuvant in rabbits and mice

In the search for more potent and less toxic immunomodulators, adamantylamide dipeptide (AdDP) was synthesized by the covalent union of amantadine with the L-alanyl-D-isoglutamine residue of muramyldipeptide (MDP). The present experiments demonstrate the ability of AdDP, co-administered with a protein immunogen, to raise or enhance a humoral response in immunized animals. BALB/c mice were immunized either by the intraperitoneal (ip) or oral route with ovalbumin (Ova) alone or combined with either AdDP or CpG oligonucleotide (ODN-CpG), a proved adjuvant. A clear adjuvant dose-response relationship was observed on the increment of Ova-specific serum antibody titers when AdDP was used as adjuvant, irrespectively of the administration route. The IgG isotype analysis showed that AdDP promotes a consistent increment in IgG1 antibodies associated with a dominant Th2 response pattern. When administered by the oral route, AdDP was at least as efficient as ODN-CpG as adjuvant. Similar results were obtained in rabbits immunized by the oral route, suggesting that the adjuvanticity of AdDP is not restricted to the murine system. In conclusion, AdDP was shown to be a powerful and non-toxic adjuvant at both systemic and mucosal levels, which makes it a promising tool for vaccine development.

[Complex evaluation of the effect of bromantane on animal behavior]

The results of experimental investigation of the effect of bromantan on the behavioral activity of rats in the open-field test were treated by a combination of the discriminant and dispersion methods. The toxic effect of the drug on the neurogenic (neurologic) mechanisms conducting the behavior is evaluated.

[Acute toxicity of bemithyl and bromithyl]

The experiments on rats showed for bemithyl LD50 = 581.48 (350.17-965.57) mg/kg and for bromithyl LD50 = 1750.30 (1463.07-2093.92) mg/kg (males) and 1584.29 (1280.46-1960.22) mg/kg (females). The therapeutic ratios are 4-6 for both drugs, while the toxicity index is 10-15 for bemithyl and 20 <196> 22 for bromithyl. It was established that ergotropic effects prevail in the toxicity of bemithyl administered in the 20-80 mg/kg dose range, while trophotropic effects are dominating at doses above 100 mg/kg. Bromithyl exhibits a dose-dependent trophotropic effect in the entire dose range.

[Effect of bromantane on the rat neurologic status in two month course]

The oral administration of bromantan for two months on a toxic dose level produced a sex-dependent psychodysleptic action upon rats: the effective (30 mg/kg), intermediate (150 mg/kg), and toxic (600 mg/kg) doses reduced the motor activity in males, while not affecting (or increasing) this activity in females. The effective dose stimulated, and the toxic dose suppressed, the research activity and increased the number of grooming episodes, while ambiguously influencing the emotional state of rats. In the initial stage of treatment, bromantan causes hypothermia; in the second month, this effect is replaced by slight hyperthermia. Prolonged administration of a large dose of bromantan oppressed food uptake and slightly increased drink uptake. Upon the bromantan treatment, the body weight increased in females and decreased in males. The bromantan treatment course increased the muscle strength of rats; the operant activity was optimized during the first month of the course. The general physiological and behavioral characteristics of animals restored within two months after termination of the treatment course. During this period, the test animals exhibited no significant behavioral symptoms indicative of the drug dependence. The two-month treatment did not lead to the development of tolerance with respect to the optimizing drug action upon the physical and operant capacity.

[An acute toxicity study of bromantane]

The toxicity of bromantan was evaluated by conventional acute tests (according to Belen'kiĭ) and by the behavioral activity data (according to Irvin). A method of integral graphical representation of the behavioral activity data is suggested, according to which the results are plotted as a "dose trajectory." Using the dose trajectory constructed for bromantan, the levels of therapeutic, toxic, and lethal doses were calculated. It was established that catecholaminergic effects account for the mechanism of therapeutic action of bromantan, while cholinergic effects determine the drug action in toxic doses.

[The effect of bromantane on the erythro- and leukocytic profile of the peripheral blood in rats]

The specific effect of bromantan on blood tissue is demonstrated in rats. In chronic injection in a dose of 30 mg/kg bromantan raised the level of hemoglobin and leukocytes. In doses of 150 and 600 mg/kg it increased at first (3 months) and then reduced the level of erythrocytes, hemoglobin, and leukocytes. Reversible poikilocytosis, granulocytosis, and agranulocytosis were encountered. Hyperchromatosis and hypertrophy of the hepatocytes were found in the tissues of the liver and hemosiderosis was discovered in the spleen. It is suggested that the blood tissue is a "target" in the toxic effect of bromantan.

[The characteristics of the neuropsychotropic activity of bromantane in laboratory animals]

Bromantan [N-2-(para-(bromphenyl)-N-2-(aminoadamantan)] possesses psychostimulating activity in experiments on animals. With LD50 8100 mg/kg (mice, intraperitoneal injection) activates simple and complicated forms of behavior, induces EEG effects typical of psychostimulators, is an antagonist of substances with a deprivationg neuropsychotropic effect. Bromantan is characterized by a positive effect on mnemonic processes and on obtaining the results of complex operant activity in rats.

Amiodarone induces two different types of disorders in mouse alveolar macrophages

It has been reported that amiodarone induces disorders of alveolar macrophages and pulmonary fibrosis, but the mechanism is not well-understood. This study was performed to elucidate the toxic mechanism from the standpoint of cellular function. Using alveolar macrophages obtained from a male Slc:ICR mouse, several injuries caused by amiodarone were compared to those caused by amantadine and mianserin as cationic amphiphilic drugs (CADs). As parameters for the drug effects, H(+)-ATPase and acid sphingomylinase activities, cellular pH, cytokine and prostaglandin releases, phagocytosis and neutral red uptake were measured. Amiodarone decreased H(+)-ATPase activity initially and subsequently increased cellular pH and decreased acid sphingomyelinase activity. These changes, which were also observed with amantadine and mianserin, were considered to be CAD-related. Amiodarone increased cytokine and prostaglandin releases and suppressed neutral red uptake and phagocytosis. These changes, being not induced by amantadine and mianserin, were considered to be specific for amiodarone. The above data suggest that amiodarone has two types of toxic effects on alveolar macrophages.

Evaluation of anti-influenza effects of camostat in mice infected with non-adapted human influenza viruses

The anti-influenza effects of camostat, a serine protease inhibitor, on in vivo influenza infections were evaluated. Mice which received non-adapted human influenza viruses intranasally, developed a reproducible infection with very low mortality. The infection was readily detected by the recovery of the virus from an oropharyngeal swab. Five-week-old ICR mice received intraperitoneal injections of saline (control), amantadine (known positive drug), or camostat, after infection with influenza A/Taiwan/1/86 virus. Virus detection was performed on day 1, 2, 3, 5, and 7 of postinfection. Both camostat and amantadine were effective in ameliorating mouse influenza. On day 5, mice injected with camostat (45%) or amantadine (50%) showed a lower virus secreting rate than those receiving saline (90%). Additionally, camostat showed strong anti-influenza effects on an amantadine-resistant type A virus and a type B virus infection in vitro. The results show that blocking the hemagglutinin cleavage is an effective target for development of an anti-influenza agent. They also demonstrate that virus detection from the oropharynx of mice, infected with non-adapted virus, is a useful in vivo influenza model.

Anti-infective therapy for viral pneumonia

The recognition of viruses as causes of pneumonia in both immunocompetent and immunocompromised hosts has expanded dramatically. The number of therapeutic agents available for treatment of these illness also has increased in the last decade. Each of these agents has demonstrated a limited therapeutic indication for treatment of viral pneumonia. Many of these agents inhibit viral DNA synthesis through actions as nucleoside analogs (such as acyclovir and ganciclovir). However, a variety of alternative mechanisms of inhibition of viral replication are used. Ribavirin, while being a nucleoside analogue, also appears to exert broad antiviral activity by a variety of enzymatic inhibitory mechanisms. Foscarnet, an inorganic pyrophosphate analogue, offers additional treatment options for herpesviruses by acting as a direct virus DNA polymerase inhibitor. The tricyclic amines amantadine and rimantadine inhibit influenza A replication by interfering with viral uncoating after cell penetration. Thus, these two agents are largely effective as prophylaxis. The search for novel antiviral drugs, such as neuraminadases inhibitors with selective influenza activity, is currently in progress.

Anticholinergic effects on memory: benztropine versus amantadine

To evaluate anticholinergic effects on cognition and other functions, we studied 60 healthy volunteers in a double-blind crossover trial of two antiparkinsonian agents, benztropine and amantadine. Benztropine 4 mg/day, but not amantadine 200 mg/day, impaired free recall and perception of time, and subjects' perception of their own memory impairment was significantly greater with benztropine. Side effects in general were worse with benztropine, particularly such anticholinergic effects as dry mouth and blurred vision, and benztropine decreased measured salivary flow to a significantly greater degree than amantadine. Our findings support the hypothesis that drugs that decrease cholinergic transmission impair storage of new information into long-term memory, but have little effect on retrieval from memory or on tasks involving only immediate memory. Clinically, anticholinergic agents can levy a considerable burden on memory and time perception.

The efficacy of amantadine and other antiviral compounds against two salmonid viruses in vitro

Various compounds, with known clinical efficacy against human viruses, were evaluated for their ability to inhibit the growth of infectious hematopoietic necrosis virus (IHNV, a rhabdovirus), and infectious pancreatic necrosis virus (IPNV, a birnavirus), in rainbow trout cell cultures. Amantadine inhibited the plaque forming ability of IHNV, at concentrations which did not affect cell growth or morphology, although it was not active against IPNV. Metisazone and bis-benzimidazole were also effective against IHNV; but they were slightly cytotoxic. Ribavirin, as expected, was active against IPNV, but was also equally effective against IHNV, although it was cytotoxic. Several other compounds were also tested but they were not inhibitory to either virus. The attraction of amantadine is the fact that relatively easy administration should be feasible.

Amantadine: evaluation of reinforcing properties and effect on cocaine self-injection in baboons

The ability of amantadine to maintain self-injection behavior and to alter self-administration of cocaine was examined in baboons using a standard intravenous cocaine self-injection procedure. Responding was maintained under a FR 80- or 160-response schedule of intravenous cocaine delivery (0.32 mg/kg per injection). Each drug injection was followed by a 3-h time-out allowing a maximum of 8 injections/day. Vehicle or amantadine doses were substituted for cocaine for a period of 15 or more days. Evaluation of a wide range of amantadine doses (0.32-32 mg/kg per injection) showed that this compound did not maintain self-administration behavior above vehicle control levels. In another experiment using the cocaine self-injection baseline, amantadine (10 or 32 mg/kg per day) was administered via a chronic intravenous infusion. Cocaine self-injection behavior was maintained and re-initiated during chronic amantadine exposure, suggesting that the reinforcing efficacy of cocaine was not modified by chronic amantadine administration.

Amantadine-induced lipidosis. A cytological and physicochemical study

The purpose of this study was to test whether or not the antiviral drug amantadine induces the structural features of lipidosis in intact animals (rats) and cultured cells, and to investigate the interactions between amantadine and phospholipids. Chlorphentermine was used as reference compound. When subchronically fed to rats at a daily dosage of approximately 180 mg/kg, amantadine induced ultrastructural symptoms of generalized lipidosis, the degree of which was, however, by far less marked than that previously reported for chlorphentermine. This was paralleled by the findings on cell cultures (rat peritoneal macrophages), where the lipidosis-inducing potency of amantadine was approximately 10-fold lower than that of chlorphentermine. As to drug-phospholipid interactions, amantadine had less marked effects than chlorphentermine upon the phase transition characteristics of phosphatidylcholine and phosphatidic acid; furthermore, amantadine was approximately 10-fold less potent than chlorphentermine in displacing Ca from phosphatidylserine monolayers. The present study has revealed a parallel between the comparatively low lipidosis-inducing efficacy inherent to amantadine and the comparatively low tendency to interact with phospholipids. It is suggested that the cage-like structure of the amantadine molecule hinders an effective intercalation of the drug into phospholipid aggregates, and that this is an essential factor responsible for the low inherent efficacy of amantadine with respect to lipidosis induction.

Influence of twenty potentially antiviral substances on in vitro multiplication of hepatitis A virus

A multiwell tissue culture system was developed to study the influence of various substances on hepatitis A virus (HAV) propagation. A panel of 20 substances of different structure types, each with known effect against at least some viruses, was studied at a concentration of 100 microM. Three substances showed reproducible inhibition. The strongest inhibitor, arabinosylcytosine, also produced cytotoxic changes in cells down to a concentration of 1 microM, and its effect was considered as nonspecific. Amantadine and ribavirin showed a moderate effect at 100 microM. A stronger inhibition was seen at 250 and 500 microM, doses that are toxic and impractical for clinical use. Although no promising candidates for antiviral treatment of hepatitis A have emerged from the present study, the assay model described here would seem useful in the screening of substances with inhibitory effects on HAV.

Comparative toxicity of amantadine hydrochloride and rimantadine hydrochloride in healthy adults

The relative toxicities of amantadine and rimantadine were compared in a double-blind, placebo-controlled study involving healthy adults. In separate studies, drugs were administered at a dosage of 200 mg/day (52 volunteers) or 300 mg/day (196 volunteers) for 4.5 days. Both drugs were well tolerated at the lower dosage. At 300 mg/day amantadine recipients had a greater frequency and severity of central nervous system (nervousness, lightheadedness, difficulty concentrating) and sleep (insomnia, fatigue) complaints compared with rimantadine or placebo recipients. Amantadine recipients also performed less well on an objective test measuring sustained attention and problem-solving ability. Both amantadine and rimantadine recipients reported adverse gastrointestinal symptoms more often than placebo recipients. Because of better tolerance at higher dosage, rimantadine offers more promise than amantadine for treatment of influenza A virus infections.