amocarzine and Onchocerciasis

Brief notes are given on drugs which have been tested at the Onchocerciasis Chemotherapy Research Centre at Tamale and Hohoe and found to have activity against Onchocerca volvulus. Ivermectin in single doses as high as 800 micrograms/kg was found to be no more effective than the standard dose of 150 micrograms/kg. The benzimidazole carbamates, mebendazole and albendazole, differ in their effects on O. volvulus. The former has microfilaricidal effects and is toxic to developing embryos surrounded by an egg shell but not the stretched microfilariae. Albendazole has no microfilaricidal activity but is toxic to all intra-uterine stages. The reasons for these differences are unclear. Early studies with amocarzine are described; the maximum tolerable dose is 20 mg/kg and the predominant activity, against the microfilariae, is marked only at doses greater than 12 mg/kg. None of the drugs tested has macrofilaricidal activity.

Topics: Albendazole; Animals; Filaricides; Humans; Ivermectin; Mebendazole; Onchocerca volvulus; Onchocerciasis; Piperazines

The hundred men from a forest area of Ghana, without vector control or ivermectin distribution, were randomized to receive a single dose of ivermectin (150 micrograms/kg body weight) on day 1 followed by amocarzine (3 mg/kg twice daily after meals) on days 8, 9 and 10 (34 patients), the ivermectin alone (33 patients) or the amocarzine alone (33 patients). Detailed clinical and laboratory examinations were made before, during and after drug administration. On day 120, all palpable nodules were excised, fixed, sectioned, stained and examined by two blinded observers and the results compared with those for nodules from untreated controls. Mazzotti-type reactions, such as itching, rash, peripheral sensory phenomena and swellings, were more severe or frequent with amocarzine than ivermectin. Pretreatment with ivermectin markedly suppressed these reactions to amocarzine but did not affect other manifestations such as dizziness and gaze-evoked nystagmus. Ocular effects were minor in all groups. Ivermectin produced minor macrofilaricidal effects on the adult male worms, marked degeneration of intra-uterine embryos, and potent microfilaricidal effects and suppressed skin microfilariae. Amocarzine did not affect the male worms or the intra-uterine embryos, was a less potent microfilaricide and did not suppress skin microfilariae. The efficacy of ivermectin plus amocarzine was similar to that of ivermectin alone. The present results do not support the findings from the Americas and show that amocarzine has no role in the treatment of onchocerciasis in Africa.

Topics: Adolescent; Adult; Animals; Dizziness; Double-Blind Method; Drug Therapy, Combination; Eye Diseases; Filaricides; Ghana; Humans; Inflammation; Ivermectin; Male; Microfilariae; Middle Aged; Onchocerca; Onchocerciasis; Onchocerciasis, Ocular; Piperazines; Pruritus; Skin

Brief notes are given on drugs which have been tested at the Onchocerciasis Chemotherapy Research Centre at Tamale and Hohoe and found to have activity against Onchocerca volvulus. Ivermectin in single doses as high as 800 micrograms/kg was found to be no more effective than the standard dose of 150 micrograms/kg. The benzimidazole carbamates, mebendazole and albendazole, differ in their effects on O. volvulus. The former has microfilaricidal effects and is toxic to developing embryos surrounded by an egg shell but not the stretched microfilariae. Albendazole has no microfilaricidal activity but is toxic to all intra-uterine stages. The reasons for these differences are unclear. Early studies with amocarzine are described; the maximum tolerable dose is 20 mg/kg and the predominant activity, against the microfilariae, is marked only at doses greater than 12 mg/kg. None of the drugs tested has macrofilaricidal activity.

Topics: Albendazole; Animals; Filaricides; Humans; Ivermectin; Mebendazole; Onchocerca volvulus; Onchocerciasis; Piperazines

An open clinical trial of amocarzine was carried out in onchocerciasis patients in Ecuador and Guatemala. Administration after food was more effective than that during fasting. The most effective and best tolerated regimen, 3 mg/kg twice daily after food for 3 days (in 312 patients), killed 73% of 1477 female worms at nodulectomy 4 months after treatment. The mean microfilarial skin count was greatly reduced within a week (6-11% Of day 0 value on day 8) and it remained low at least 6 months (14-18% on day 180). Follow-up of a higher dose 3 day regimen taken while fasting showed microfilaridermia of 7-9% of the day 0 value 2 years after treatment.

Topics: Adult; Animals; Cohort Studies; Combined Modality Therapy; Drug Administration Schedule; Drug Evaluation; Ecuador; Female; Filaricides; Follow-Up Studies; Guatemala; Humans; Onchocerca; Onchocerciasis; Pilot Projects; Piperazines; Skin

The clinical investigations with three types of a three days regimen of amocarzine permitted to adjust the fixed dosing to the body weight related dosing and subsequently the administration of amocarzine from fasting state to drug intake after food. The main objective to reach a dose with predictable and sustained absorption was achieved, and this in turn proved to be onchocercacidal and safe. A combined clinicopharmacokinetic study showed enhancement and consistency of amocarzine absorption after food. Quantitative assessment of the urinary excretion confirmed the presence of the N-oxide metabolite, which qualitatively was visible by a urine colorimetry. This assay proved useful for drug monitoring. Ultrasonography of onchocercal skin nodules detected changes within the nodules following amocarzine therapy. Histology after nodul-ectomy at four months post-therapy showed that 57% of the female worms were dead, 24% necrobiotic, and 19% alive; male worms were more necrobiotic. Skin microfilariae were reduced within one week to about 10% of the initial level and after one year they remained at about 20%. Skin punch biopsies on day 5 showed that most microfilariae were dead or moribund. Ocular reduction of microfilariae was also observed, although it was slower than in the skin. The visual acuity improved within the one year's observation time. Ocular and clinical tolerability was good, with one exception of neurological disturbance, which was fully reversible. Sequential testing of the liver function showed average values within the normal range. In conclusion, a repeat low dose regimen of amocarzine (3 mg/kg twice daily post-prandially for three consecutive days) was well absorbed with predictable plasma levels, macro- and microfilaricidal with good local and systemic tolerability in patients with moderate to heavy onchocerciasis. Amorcarzine is recommended for further clinical investigations, particularly in females and juveniles. Urine colorimetry and nodular ultrasonography are recommended for optional monitoring of amocarzine.

Topics: Administration, Oral; Adult; Animals; Biological Availability; Drug Administration Schedule; Drug Tolerance; Eye; Female; Filaricides; Guatemala; Humans; Male; Microfilariae; Onchocerca; Onchocerciasis; Onchocerciasis, Ocular; Piperazines; Skin; Ultrasonography

The objective of this multidisciplinary clinical investigation was to test whether amocarzine was absorbed effectively and safely in patients of two races and either sex infected with Onchocerca volvulus while living in the holoendemic area of Esmeraldas Province, Ecuador. The prerequisite for a systemic onchocercacidal effect is the regular absorption of orally administered amocarzine. Single dosing after overnight fasting proved to produce irregular absorption of amocarzine, although some microfilaricidal effect was achieved. A pilot study with repeated low dose and postprandial administration of amocarzine showed a regular and predictable absorption with acceptable tolerability and a microfilaricidal effect lasting up to one year post-therapy. Since amocarzine and its major N-oxide metabolite are coloured agents, urine colorimetry was used to assess the urinary excretion of the N-oxide qualitatively. For the postprandial drug regimens plasma concentrations of amocarzine and its metabolite were determined at two selected time points in patients of two races and either sex; the results showed no major differences. Excision of onchocercal nodules was performed four months post-therapy. The pooled results of the histologic analysis of 100 patients with the same drug regimen read under blinded condition showed that 65% of the adult female worms were dead, 20% necrobiotic and 15% alive. The male worms were fewer and mainly necrobiotic. Control worm populations in Esmeraldas without chemotherapy showed that on the average 81.5% were alive and 18.5% dead. Amocarzine was also microfilaricidal producing a reduction of skin dwelling microfilariae to about 10% of the initial value within the first week after start of therapy and lasting for half a year at a 20% level. The reduction of ocular microfilarial was slower and reached 35-40% after one year. The general tolerability was acceptable to good. Reversible dermal reactions were usually mild and peaked as a rash in 57% of the patients on day 6. No prohibitive ocular intolerance was observed. Mild and reversible dizziness peaked on day 4 in 74% of patients. A positive reversible Romberg sign was found in 12 patients on day 4. Amocarzine, the first oral micro- and macrofilaricidal agent administered as a low dose repeat regimen (3 mg/kg twice daily and postprandial for three consecutive days) can be recommended for oral onchocercacidal therapy in adult patients. Clinical trials in juveniles should be encouraged.

Topics: Absorption; Adult; Animals; Black People; Colorimetry; Drug Administration Schedule; Drug Tolerance; Ecuador; Female; Filaricides; Humans; Indians, South American; Male; Microfilariae; Onchocerca; Onchocerciasis; Onchocerciasis, Ocular; Piperazines; Skin

Skin punch biopsies were performed in 54 selected patients with onchocerciasis participating in a clinical trial with amocarzine (CGP 6140) in Ecuador and Guatemala. Skin snipping for counting microfilariae of Onchocerca volvulus was done before treatment (day 0) and day 4 and 8 following start of the therapy which consisted of 3 mg/kg amocarzine postprandially twice daily for three consecutive days. The mean microfilarial skin density has been reduced by 45% on day 4 and 95% on day 8. Skin punch biopsies were taken on day 5, within 1 cm from the snip site on the iliac crest. Histopathologic examination revealed that the vast majority of the microfilariae in the upper as well as in the deeper dermis were degenerated or necrotic, surrounded often (57%) by minute foci of fibrinoid change of the collagen. There was usually slight, less frequently moderate eosinophilic, lympho-plasmocytic and initial histocytic inflammatory reaction in the vicinity. Microfilariae were frequently (69%) found at the dermal-epidermal junction and in the epidermis. Occasionally (7%) intra-epidermal microabscesses were noted. Microfilariae were detected also in the lumen of some dermal lymphatic vessels. Therefore it is concluded that amocarzine showed marked microfilaricidal effects in the skin of patients with onchocerciasis as evidenced histologically by mainly destroyed or moribund microfilariae which induced a mild to moderate inflammatory cell reaction.

Topics: Adult; Animals; Biopsy, Needle; Ecuador; Epidermis; Female; Guatemala; Humans; Male; Microfilariae; Onchocerca; Onchocerciasis; Piperazines; Skin

The possible influence of sex, race and of postprandial administration conditions (either immediately after the end of meal or one hour later) on the plasma concentrations of amocarzine and its N-oxide metabolite, CGP 13 231, was investigated. 71 Ecuadorian patients (48 males and 23 females) of two different races (Indio and Negro) infected with Onchocerca volvulus participated in the study. The concentrations were measured on day 3 at times 3 and 6 h after postprandial administration in the morning of a treatment with either a dose of 5 mg/kg of amocarzine once daily (12 patients) or 3 mg/kg twice daily (59 patients) for 3 days. The concentrations of unchanged drug and of CGP 13 231 measured after the 5 mg/kg treatment were in the low range of those expected from dose proportionality by the comparison with the 3 mg/kg. After the 3 mg/kg dose, no significant difference in concentration of both compounds were detected between the male and female patients between Indio and Negro patients, between the administration immediately after food intake and one hour later. The only detected difference (P = 0.05) was that between Indio and Negro patients for the concentrations of CGP 13 231 at time 3 h. This difference was not confirmed at time 6 h. Therefore, the administration of amocarzine either immediately or one hour after food intake appeared to produce reproducible absorption conditions which were not influenced by sex and race.

Topics: Absorption; Administration, Oral; Black People; Drug Administration Schedule; Ecuador; Female; Filaricides; Food; Humans; Indians, South American; Male; Onchocerciasis; Piperazines; Sex Characteristics

Ultrasonography of onchocercal skin nodules was performed with an ophthalmologic real time linear scanner with a B probe of 10 MHz. A clinical trial in Guatemala with amocarzine (CGP 6140)--a new oral macrofilaricidal compound--investigated three repeat dose regimens and one placebo control group, each group consisting of six patients. Onchocercal nodules were scanned before treatment and on day 10, 30 and 60 after start of amocarzine. A total of 28 treated and 8 additional untreated nodules were analysed and compared with the histologic findings following nodulectomy at day 60. Of the 28 treated nodules, 21 were of onchocercal origin and seven were lymph nodes. The correlation between ultrasonography and histology was good in 25 patients, but did not match in three. In 20 out of 21 treated nodules a progressive ultrasonographic change over two months was seen. Of the eight additional untreated nodules, five were of onchocercal origin, one was a lymph node, one an epidermoid cyst and in one only fibrous tissue was detected. The ultrasonography correlated well to histology in seven nodules but not in one. In five onchocercal nodules no change was observed over two months. For initial control purposes six nodules were excised around day 10, four were of onchocercal origin and two were lymph nodes. The correlation was good in four. The present results indicate that an ophthalmologic real time linear scanner can be used in the bidimensional mode as a non-invasive method to assess sequentially the events in superficial onchocercal nodules following chemotherapy with amocarzine. This is the first objective non-invasive method permitting sequential assessment of the content of onchocercal nodules and it is far superior than subjective sequential manual palpation.

Topics: Animals; Filaricides; Follow-Up Studies; Guatemala; Humans; Lymph Nodes; Male; Onchocerca; Onchocerciasis; Piperazines; Skin; Ultrasonography

Transmission electron microscopy was used to demonstrate the effects of amocarzine (CGP 6140) on the fine structure of Onchocerca volvulus microfilariae (mf) in skin biopsies from patients treated orally in Guatemala or transepidermally exposed in Liberia. After 6-10 hours exposure to the drug most mf did not show any alterations and only a few mf contained increased numbers of vacuoles in the cytoplasm and clefts between cuticle and hypodermis. At 20-48 hours after treatment most of the mf showed distinct signs of damage. Most frequently seen was disintegration of the cytoplasm of the afibrillar portion of the muscle cells. Some mf showed also disintegration of the myofilaments and of the internal structure of the mitochondria in the muscle cells. Other signs were progressive separation of the cuticle from the hypodermis, increase of intracellular vacuoles and clefts and in some mf condensation of the cytoplasm. The type and the site of the morphological alterations were the same after both forms of amocarzine administration. The degree of morphological changes increased with the length of time of exposure to the drug. Microfilariae with morphological alterations were nearly always surrounded by adherent host cells, mostly eosinophils and macrophages.

Topics: Administration, Cutaneous; Administration, Oral; Animals; Filaricides; Guatemala; Humans; Liberia; Microfilariae; Microscopy, Electron; Mitochondria; Onchocerca; Onchocerciasis; Piperazines; Skin; Vacuoles

Eleven male patients from Mali with Onchocerca volvulus infections received in random order a 1200 mg single oral dose of CGP 6140 after an overnight fast and after food intake. The concentrations of CGP 6140 and of its N-oxide metabolite, CGP 13231, were measured in plasma and urine. Mean (+/- s.d.) AUC CGP 6140 values were 67.0 +/- 10.8 mumol l-1 h in fed and 22.0 +/- 17.2 mumol l-1 h in fasting patients. The mean maximum concentrations (Cmax) in plasma +/- s.d. were 12.7 +/- 2.8 mumol l-1 in fed and 4.7 +/- 4.1 mumol l-1 in fasting patients. The median time to Cmax was 3 h in fed and 2 h in fasting patients. Mean (+/- s.d.) AUC of the N-oxide metabolite was 59.9 +/- 10.7 mumol l-1 h in fed and 23.4 +/- 16.2 mumol l-1 h in fasting patients. The urinary recovery was less than 0.5% of dose for CGP 6140 in both fed and fasting conditions. It was 30.1 +/- 11.5 and 11.4 +/- 8.0% of the dose for the N-oxide metabolite in fed and fasting conditions, respectively. Variability in plasma concentrations and urinary recovery of CGP 6140 and of the N-oxide metabolite was greater in fasted patients. The low solubility of CGP 6140 in aqueous solutions at neutral pH and its higher solubility at acidic pH might explain the increase in bioavailability after food intake. The administration of CGP 6140 after food intake is therefore recommended for an optimal systemic effect.

Topics: Administration, Oral; Biological Availability; Filaricides; Food; Humans; Male; Onchocerciasis; Piperazines

Topics: Adult; Animals; Clinical Trials as Topic; Humans; Male; Onchocerciasis; Parasite Egg Count; Piperazines; Schistosomiasis

The involvement of eosinophils in the host reaction to microfilariae (mf) of Onchocerca volvulus was studied by immunohistochemistry and immunoelectron microscopy. Skin biopsies were obtained from patients after transepidermal administration of the microfilaricide amocarzine. At 20-28 h after the application of amocarzine, mf were degenerated or dead and a marked eosinophil-parasite adherence (EPA) reaction was seen, with intense staining for intra- and extracellular eosinophil granule proteins such as eosinophil cationic protein (ECP) surrounding the mf. Immunoelectron microscopically the eosinophil granule matrix in intact and necrotic eosinophils was specifically labeled, whereas granules whose matrix had dissolved showed no specific gold particle binding. As specific labeling was seen on lowly electron-dense material adjacent to matrix-depleted granules, the material was regarded as released eosinophil granule matrix material. Intact and necrotic eosinophils, matrix-containing as well as matrix-depleted eosinophil granules, and released eosinophil granule matrix material were observed on the surface of damaged mf and between collagen fibers. The coincidence of mf degeneration, EPA reaction, and release of eosinophil granule matrix material on damaged mf and collagen fibers indicated a role of eosinophils and eosinophil granule matrix protein in the host reaction to mf after amocarzine application.

Topics: Adult; Animals; Blood Proteins; Cytoplasmic Granules; Eosinophil Granule Proteins; Eosinophil-Derived Neurotoxin; Eosinophils; Female; Filaricides; Humans; Immunohistochemistry; Inflammation Mediators; Male; Microscopy, Immunoelectron; Middle Aged; Onchocerca volvulus; Onchocerciasis; Piperazines; Ribonucleases; Skin

A recently developed polymerase chain reaction (PCR)-based assay is significantly more sensitive than current methods for diagnosing Onchocerca volvulus infection, and it overcomes many difficulties in identifying active onchocerciasis. Since chemotherapy is widely used to treat onchocerciasis, the utility of PCR in assessing responses to treatment and in predicting recrudescence is important. Twenty-eight patients who had skin snips positive for microfilariae (Mf) were studied 120 days after receiving amocarzine, when each was negative for Mf: 16 (57%) were positive for O. volvulus DNA in the PCR-based assay. Of these, 14 (88%) were Mf positive when reassessed parasitologically on day 240, and all were Mf positive on day 365. Equally important was the finding that 12 patients had cleared both Mf and Mf DNA; only 1 was Mf positive at day 240. This suggest that the PCR-based assay provides a sensitive means assessing infection status after macrofilaricidal chemotherapy and is an early predictor of persons likely to have a recurrence of Mf.

Topics: Animals; Base Sequence; DNA Primers; DNA, Helminth; Ecuador; Filaricides; Humans; Molecular Sequence Data; Onchocerca volvulus; Onchocerciasis; Piperazines; Polymerase Chain Reaction; Recurrence; Sensitivity and Specificity; Time Factors

Amocarzine has been reported to have onchocercacidal effects. Four months posttherapy the majority of adult worms were dead or moribund. The effect of skin microfilariae lasted up to one year as reflected by markedly reduced microfilaridermia. Since the duration of the onchocercacidal effect of amocarzine beyond one year was unknown and since such an effect may influence the planning of future control strategies, efforts were made to follow-up the already treated amocarzine patients for a second year. The present study from Latin America showed that various amocarzine drug regimens produced a prolonged reduction of microfilaridermia at the end of the second year following the initial therapy, the best levels were about 7-17% of the initial parasite load in the skin for some three days amocarzine regimens. Such an effect occurring in a transmission area of onchocerciasis in Latin America provides additional, although indirect, evidence of a macrofilaricidal effect of amocarzine. Similar experiences of a prolonged amocarzine effect on skin microfilariae has also been observed in West Africa (Ghana, Mali). Preliminary results of retreatment schedules at the start of the third year post-initial therapy showed that simplified postprandial dose regimen of one or two days were well tolerated. It is premature at the time of this report to judge upon their ultimate efficacy, but they had significantly reduced levels of moderate microfilaridermia.

Topics: Animals; Ecuador; Filaricides; Follow-Up Studies; Guatemala; Humans; Microfilariae; Onchocerca; Onchocerciasis; Piperazines; Skin

The concentrations of CGP 6140 [4-nitro-4'-(N-methyl-piperazinylthiocarbonylamido)-diphenylamine] and of its N-oxide metabolite, CGP 13,231, were measured in plasma and urine after single oral dose of 100-1600 mg of CGP 6140 to 41 fasted Ghanaian patients with Onchocerca volvulus infections. The absorption of CGP 6140 was rapid and its terminal elimination half-life was about 3 h. The plasma concentrations of CGP 6140 were essentially proportional to the dose. A greater variability in plasma concentrations was apparent after the 800 and 1600 mg doses indicating a poor bioavailability of the drug administered in fasting conditions to several patients. In plasma, the concentrations of CGP 13,231 were similar to those of CGP 6140. The amount of CGP 13,231 excreted in urine was 25-40% of the dose of CGP 6140 whereas only 1.5% was excreted as unchanged drug. If a single dose of drug is used for the treatment, the plasma concentration would be maintained for 3-4 h at a high level. At 8 h, the concentration falls to about 10% of the Cmax. If sustained plasma concentrations of the drug are needed for efficacy, twice daily administration would maintain the minimum concentration at about 10% of the Cmax.

Topics: Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Filaricides; Half-Life; Humans; Male; Onchocerciasis; Piperazines

Topics: Animals; Guatemala; Humans; Microfilariae; Onchocerca; Onchocerciasis; Piperazines; Ultrasonography; Vitreous Body

An in vivo drug screen for identifying new compounds with activity against Onchocerca macrofilariae was developed using male Onchocerca gibsoni implanted subcutaneously in outbred mice. There were several similarities (Mel W, CGP 20376, CGP 6140, levamisole) and two differences (suramin, furapyrimidone) between levels of drug efficacy in this model and activity against natural infections of O. gibsoni and O. volvulus. There was considerable variation in the mouse reaction. This mouse model is a potentially useful primary screen for macrofilaricidal drugs against Onchocerca.

Topics: Animals; Anthelmintics; Arsenicals; Filaricides; Male; Mice; Onchocerca; Onchocerciasis; Piperazines; Random Allocation; Thiazoles

An in vitro system for chemotherapeutic research using adult male Onchocerca gutturosa has been developed as a model for O. volvulus. Using a culture system consisting of medium MEM + 10% heat inactivated foetal calf serum (IFCS) + LLCMK2 (monkey kidney) feeder cells in an atmosphere of 5% CO2 in air, we examined the effects of a range of antiparasitic drugs on worm motility. Ivermectin, levamisole, furapyrimidone, Mel W, chloroquine, metrifonate, flubendazole, amoscanate and the Ciba-Geigy compounds CGP 6140, CGP 20'376 and CGI 17658 either immobilized or significantly reduced motility levels at a concentration of 5 X 10(-5) M or less within a 7-day period. Worms were affected at very low concentrations by ivermectin (effective conc. to reduce motility levels to 50% of controls, 3.14 X 10(-8) M), levamisole (7.95 X 10(-8) M), CGP 6140 (8.87 X 10(-9) M) and CGP 20'376 (2.78 X 10(-8) M). Difficulties were experienced in accurately repeating the immotile endpoint for levamisole due to an inconsistent partial recovery of motility. Over a 7-day period diethylcarbamazine had little effect on motility levels, while suramin caused a slight increase in activity compared to controls at some timepoints. Subsequent experiments demonstrated some differences in drug efficacy depending on the presence or absence of serum and feeder cells in the culture system probably because of drug avidly binding to serum proteins. However, serum and cells were found to be essential ingredients of the culture system to maintain worms in good condition, indicating that new drugs should be evaluated both in the presence and absence of serum and cells. Comparisons were made between the responses of O. gutturosa and Brugia pahangi to certain drugs and these species were found to significantly differ in their sensitivities to ivermectin and a novel compound (Wellcome), indicating that Onchocerca parasites should be used wherever possible for compound identification and development intended for the treatment of onchocerciasis. The in vitro system described here, using male O. gutturosa, provides a basis for further research and a practical alternative to O. volvulus.

Topics: Animals; Anthelmintics; Brugia; Filaricides; Ivermectin; Levamisole; Male; Movement; Onchocerca; Onchocerciasis; Piperazines; Thiazoles