Skip to main content

Fluazuron orally administered to guinea pigs: pharmacokinetic and efficacy against Amblyomma sculptum



Brazilian spotted fever (BSF), the most lethal tick-borne disease in the Western Hemisphere, is caused by the bacterium Rickettsia rickettsii and transmitted by the bite of Amblyomma sculptum. Capybaras are considered primary hosts of this tick and amplifier hosts of R. rickettsii, generating new infected lineages of A. sculptum in BSF-endemic areas. To define a possible treatment regimen for controlling the tick A. sculptum in capybaras, the aim of this study was to establish an effective fluazuron (FLU) dose to control A. sculptum larvae in artificially infested guinea pigs.


In Study I (pharmacokinetic and pharmacodynamic analysis), 24 guinea pigs were divided into four equal groups: control group (CG; untreated) and treated groups receiving FLU administered by gavage in three doses: G1—1 mg/kg, G2—5 mg/kg and G3—10 mg/kg, once a day for 15 days (d0 to d + 14). Blood samples were collected from the animals of the treated groups before and at d + 1, + 2, + 4, + 7, + 15 and + 21. The guinea pigs were artificially infested at d + 7 with A. sculptum larvae, and specimens were recovered at d + 11 to d + 14 and kept in a climatized chamber for 14 days. In Study II (evaluation of pharmacokinetic parameters), one group of eight animals received FLU administered by gavage in a single dose of 10 mg/kg, and blood samples were collected before and on day 0 (8 h after treatment), + 1, + 4, + 7, + 15, + 21 and + 28 after single FLU administration. FLU was analyzed in plasma samples by high-performance liquid chromatography with ultraviolet detection.


FLU plasma concentrations increased quickly, indicating rapid absorption, and decreased slowly. Some larvae from all treated groups exhibited morphological and behavioral changes. FLU interfered in molting, and the efficacy obtained was 100% for all treated groups.


The results offer promising perspectives for the development of a palatable feed cube containing FLU for free-living capybaras to control A. sculptum and also to prevent BSF in areas where capybaras have been shown to play a primary role.


Amblyomma sculptum belongs to a complex of five other tick species, of which it has the widest distribution in Brazil [1]. This arthropod species has low parasitic specificity, mainly in immature stages, being able to infest several vertebrate host species, including humans as accidental hosts. However, capybaras, tapirs and horses are considered its preferred hosts [2].

A factor that contributes to the excessive infestation of these ticks in the environment is the population imbalance of capybaras in certain areas, haing an ecological and public health impact [3]. Capybaras are the largest living rodent [4] and have the capacity to adapt to anthropic habitats, with important reproductive potential. They also live in large groups and do not have predators. These factors have led to a considerable increase in the population density of capybaras, and consequently of ticks [5].

Brazilian Spotted Fever (BSF) is an infectious disease with high case fatality risk, caused by the bacterium Rickettsia rickettsii [6] and transmitted through the bite of ticks, mainly A. sculptum [7].

To obtain effectiveness in controlling BSF, the control of ticks such as A. sculptum is necessary to reduce their number in both animals and the environment. The immature stages of ticks (especially larvae) are more sensitive to chemical control measures than adults [8]. Therefore, reducing the presence of ticks in the immature phase is more effective than controlling the number of adult ticks. Furthermore, the correct use of acaricides in livestock is necessary to control environments infested by A. sculptum, since the concomitant presence of wild animals such as small mammals is common. The major issue in that case is that these wild animals can act as hosts of ticks in the immature stages, becoming keepers and dispersers of these arthropods in the environment [9].

Despite the severity of BSF, some in vitro studies have been published on the efficacy of A. sculptum control [10,11,12], and they have not been reported in in vivo studies.

The main chemical groups for tick control applied on hosts are carbamates, organophosphates, amidines, pyrethroids, macrocyclic lactones and phenylpyrazoles [13]. Fluazuron (FLU) belongs to a class of insect growth regulators (IGRs), and it is a chitin synthesis inhibitor [14]. FLU acts by interfering with molting and hatching [15] and is widely used to control Rhipicephalus microplus on cattle [16,17,18].

Few studies have described the oral administration of FLU to control ectoparasite in animals. For example, it was considered viable to control Sarcoptes scabei in pigs [19]. In addition, the administration of FLU in feed cubes proved to be viable for the control of fleas on wild rodents [20, 21].

To enable future development of feed cubes containing fluazuron for the control of the tick A. sculptum in capybaras, the aim of this study was to establish the bioavailability and the effective dose of FLU administered orally for the control of A. sculptum larvae using artificially infested guinea pigs (Cavia porcellus).



Thirty-two clinically healthy guinea pigs (16 males and 16 females), 6–8 months old, weighing 0.6–1 kg, were included in the study. The animals had not been treated with ectoparasiticides in the 3 months before treatment. All animals were housed individually in cages whose dimensions were 0.60 m (height) × 1.2 m (width) × 0.60 m (depth), placed on a masonry floor, with supply of freshwater ad libitum and dry feed for guinea pigs twice a day, according to the weight and need of each individual. The temperature of the room where the animals were kept was controlled by air conditioning, keeping it at 21 ± 1 °C. Also, environmental enrichment measures were adopted to reduce stress caused by the confinement and management necessary to conduct the study.

Groups and treatment

Two studies were carried out, as follows:

Study I: This study aimed to determine the influence of FLU doses on plasma concentrations and efficacy. For pharmacokinetic and pharmacodynamic (PK/PD) analysis, 24 animals were divided into four groups (six animals/group): control group (CG; untreated) and groups 1 (G1), 2 (G2) and 3 (G3), receiving FLU administered by gavage in three doses, G1—1 mg/kg body weight, G2—5 mg/kg body weight and G3—10 mg/kg body weight, once a day for 15 days (d0 to d + 14). The guinea pigs were randomized by sex and weight. A decreasing list for each sex was prepared with the weight of each animal. Then the animals were divided into four groups (CG, G1, G2 and G3), and a lottery was conducted from the heaviest to the lightest animal, allocating one in each group, and so on, until attaining six replicates in the four groups, with three males and three females in each group.

Study II: This study aimed to perform descriptive pharmacokinetics. Determination of the pharmacokinetic parameters of FLU was obtained by evaluating the single-dose, compartmental model study. For evaluation of pharmacokinetic parameters, one group with eight animals received FLU administered by gavage at a single dose of 10 mg/kg.

Pharmacokinetic analysis

Study I: Blood was collected from the animals of G1, G2 and G3 in heparin tubes by jugular venipuncture before and after the first treatment with FLU on days + 1, + 2, + 4, + 7, + 15 and + 21.

Study II: Blood samples were collected before and on days 0 (8 h after treatment), + 1, + 4, + 7, + 15, + 21 and + 28 after administration of a single FLU dose.

In both studies the plasma was obtained by centrifugation at 756 g for 10 min at 4 °C and was stored at − 20 °C until analysis.

Pharmacokinetic parameters were determined using the PK solver program (Microsoft Excel®, Redmond, WA, USA), using the non-compartmental model of extravascular administration. All PK parameters were calculated using the individual plasma concentration versus time data. The maximum measured concentration for a particular animal (Cmax) and the time from dosing to the maximum concentration (Tmax) were measured individually. The area under the curve from zero to last time t (AUC0-t) was calculated using the linear trapezoidal method and extrapolated to infinity (AUC0-∞).

Results are expressed as arithmetic mean ± standard deviation (SD). Data were statistically analyzed by one-way ANOVA followed by the Tukey test for multiple comparisons using GraphPad Prism 6.0 with 95% significance (p ≤ 0.05).

Analytical procedures

The plasma concentrations of FLU were analyzed by high-performance liquid chromatography (HPLC) with ultraviolet detection and solid-phase extraction (SPE) according to the procedure described by Ferreira et al. [22], adapted and optimized for guinea pig plasma. Plasma samples were subjected to SPE clean-up using Discovery 18-LT extraction cartridges (500 mg, 3 ml) (Supelco, USA) connected to a Visiprep SPE vacuum manifold (Supelco, USA), using acetonitrile as eluent solvent. The eluate was evaporated to dryness and reconstituted in 100 μl acetonitrile. The chromatographic separation was performed using a C18 column (Kromasil, 3.5 µm; 4.6 × 100 mm; Tedia, Rio de Janeiro, Brazil), preceded by a C18 guard column (Kromasil, 3.5 µm; 4.6 × 10 mm; Tedia, Rio de Janeiro, Brazil), both maintained at 25 °C. The mobile phase consisted of acetonitrile: water (80:20, v/v) with a flow rate of 1.0 ml/min. The UV wavelength was set at 260 nm, and the injection volume was 20 µl.

Efficacy studies

The larvae of A. sculptum used in the experiment were obtained from colonies maintained in rabbits in the Laboratory for Experimental Chemotherapy in Veterinary Parasitology of Federal Rural University of Rio de Janeiro.

To evaluate whether FLU could interfere with the ecdysis of engorged A. sculptum larvae, the guinea pigs of the treated groups received FLU by gavage at three different doses once a day on experimental days 0 to 14 (Study I).

On d + 6, a calico bag was attached on the back [23] of each animal (including the treated group) with Unna’s paste [24] and adhesive plaster. All guinea pigs (tick-bite naïve) were infested with approximately 1000 unfed A. sculptum larvae on d + 7 (the number of larvae used for infestation process was not determined by individual counting but taken from egg mass weights, with a count of eggs by gram, whereas the egg hatching percentage was pre-determined).

The first observation was performed after 24 h, the period needed for larval attachment. Daily, from d + 8 to d + 14, the calico bags were inspected and naturally detached engorged ticks were collected, counted and immediately transferred to an incubator at 27 ºC and 85% RH, where they were kept. After this, all ticks were evaluated and counted as alive or dead.

Statistical analysis of the number of engorged larvae detached was performed regarding data normality, using the Shapiro-Wilk test, between the experimental groups.

The average percentage data of molting from engorged larvae to nymph were used to determine whether there was a significant difference using ANOVA (a criterion) between the experimental groups. In all analyses a significance percentage ≥ 95% was considered. Analyses were performed using the statistical program BioEstat 5.3 [25, 26].


Pharmacokinetic analysis

Clinically, no adverse reactions were observed in any of the guinea pigs treated with FLU administered by gavage. In all experimental groups, plasma concentrations of FLU were quantified at all post-treatment sampling times.

The mean values of FLU plasma concentration of each group (Study I) are shown in Table 1.

Table 1 Mean ± SD of plasma concentration of fluazuron (−1) in guinea pigs treated orally in multiple doses with doses of 1 mg/kg, 5 mg/kg and 10 mg/kg during the treatment period

Daily dose administrations for 15 days generated concentrations of FLU in plasma ranging from 50.87 to 400.67−1 at the lowest dose (1 mg/kg), from 164.44 to 509.99−1 at the medium dose (5 mg/kg) and from 293.84 to 701.43−1 at the highest dose (10 mg/kg). The lowest dose presented lowest concentration values in plasma compared with medium and highest dose, since the statistical analyses showed significant difference (p < 0,005) at the first day of evaluation (Day + 1). However, for medium and highest doses, although increasing the dose resulted in an increase of FLU plasma concentration, multiple doses (once a day for 15 days) did not lead to an increase of FLU concentrations over the course of treatment at both doses—no significant differences were observed between the evaluation days.

In Study II, the FLU plasma concentration versus time curves after single treatment are shown in Fig. 1. FLU plasma concentrations increased quickly, indicating rapid absorption, reaching Cmax of 356.55 ± 133.75 ng/ml at 0.77 ± 0.35 days (Tmax), with absorption intervals (AUC0-t) of 2327.99 ± 673.39, ng/ml*d, and slow elimination with t1/2 of 6.94 ± 1.47 (Table 2).

Fig. 1
figure 1

Mean ± SD plasma concentration of fluazuron following orally administration of fluazuron (10 mg/kg) to guinea pigs (n = 8)

Table 2 Pharmacokinetic parameters of fluazuron following orally administration of fluazuron (10 mg/kg) to guinea pigs (n = 8)

Efficacy studies

All data regarding efficacy can be seen in Table 3. The ticks detached from d + 11 to d + 14, and the means of recovery values of engorged specimens were 266.8 (± 54.6) for CG, 419.2 (± 276.0) for G1, 427.2 (± 244.6) for G2 and 371.3 (± 203.1) for G3 (Table 3).

Table 3 Evaluation of detached and molting process of engorged larvae of Amblyomma sculptum recovered from artificially infested guinea pigs for control and fluazuron treated groups (at 1, 5 and 10 mg/kg)

The results showed that the data had nonparametric distribution. Data were log10 transformed for normalization. The Shapiro-Wilk test was used, noting that the data reached a normal distribution. Later, ANOVA (a criterion) was used to compare the mean number of engorged larvae recovered between the experimental groups. The results showed no significant difference (p = 0.8123) for engorged larvae detached.

Immediately after detachment, some larvae from all treated groups, mainly G3, although alive, exhibited morphological and behavioral changes, such as stunted size, elliptical shape, fragile integument and lethargy.

The mean molting percentage for the control group was 92.4% (± 7), while for all treated groups it was 0 (100% efficacy). There was a significant difference between the mean molting percentage of the control group and the three medicated groups (p < 0.0001).

After the molting period, all larvae from the treated groups were shriveled and darker. In the control group, no morphological or behavioral alterations were observed.


In this study, we chose the guinea pig (C. porcellus), a close relative of the capybaras (Hydrochaeris hydrochaeris), as the experimental model. Both belong to the Caviidae family and have similar behavior and physiology [27]. These preliminary tests were conducted in guinea pigs because of the facility of handling, since they are smaller and more docile than capybaras.

Fluazuron has been used in the control of the tick Rhipicephalus microplus [16,17,18], but few controlled studies are available on the control of heteroxenous ticks, and in all cases the drug was applied topically [28,29,30].

No statistical difference in the count of detached engorged larvae between the groups was observed. However, despite this absence of the knockdown effect of FLU used as an acaricide, 14 days after engorged larvae incubation, all larvae from treated groups were dead. Furthermore, the engorged larvae, mainly from G3, exhibited morphological and behavioral changes. Oliveira et al. [28], in a study of rabbits treated with different doses of FLU (1.25 to 150 mg/kg, poured on) to control R. sanguineus, observed the same morphological and behavioral changes in engorged nymphs in groups that received doses of 10 mg/kg. Probably the continued use and the route (oral instead of topical) of FLU applied to the animals of this study influenced the alterations observed even in the group receiving the lowest dose (1 mg/kg).

To determine whether there was a residual effect of FLU, other infestations of the same animals would be necessary, but since there are several studies proving that guinea pigs acquire resistance to ticks after a first infestation [31,32,33,34,35], we chose not to infest the animals again.

Data obtained from Study I showed an increase in plasma concentration of FLU with increasing dose on day + 1. However, from day + 4 until the last day of evaluation (+ 21), mean plasma concentrations did not differ significantly between groups. Efficacy results showed that even the lowest dose achieved 100% efficacy against larval molting. These results can allow choice of a dose between 1 and 10 mg/kg (orally) in further studies to control A. sculptum on capybaras.

In Study I, on d + 7, G1 had plasma FLU concentration of 98.12−1 (± 19.89), similar to the result of Study II on the same experimental day (d + 7). Since in the multiple dose study (Study I), 100% efficacy was obtained against conclusion of molting at plasma concentrations of FLU close to 100−1, perhaps treatment every 7 days with oral FLU dose of 10 mg/kg would be sufficient to control A. sculptum in guinea pigs and possibly in capybaras as well.

Pasay et al. [19] administered FLU orally for 7 days (10 mg/kg/day) to control S. scabei infestation in three pigs and achieved plasma peaks of 300–800−1 on day 7, similar to the result observed in Study I, with average of 701.43−1 on day 4 (plasma peak) in animals treated with 10 mg/kg/day. Although those authors did not calculate the pharmacokinetic parameters, we observed the same behavior, with rapid absorption and slow elimination until no detection on day 28.

The use of FLU as ectoparasiticide and its pharmacokinetic parameters were described by Lopes et al. [18] and Ferreira et al. [22] for pour-on formulations in cattle (2.5 mg/kg, single dose). However, according to Flajs and Grabnar [36], although the comparison of pharmacokinetic parameters between different species and with different administration routes is not recommended, it is still possible to compare the average time when levels of the drug can be detected in the blood plasma.

In Study II, we observed the same pattern of quick absorption and slow elimination of FLU as reported by Lopes et al. [18] and Ferreira et al. [22].

No data exist on effective systemic FLU dosages for the control of A. sculptum in guinea pigs or capybaras, and there are only a few studies in which FLU was given orally to animals for control of fleas [20, 21], mites [19] and ticks [20]. The latter research group conducted a field trial of FLU in woodrats against fleas and ticks, but it did not reduce tick counts during a year of evaluation, with doses from 1 to 40 mg/kg given in feed cubes. However, the authors attributed the absence of count reduction to the extended life cycle of the species of ticks in the studied area (e.g. Ixodes pacificus can take as long as 3 years to complete its life cycle). It is possible that in a controlled study, the authors would have observed the results they expected.

The population imbalance of capybaras in certain areas is indicated as the main cause of excessive tick infestation, causing an important ecological impact, with risk to public health due to the transmission of the bacterium R. rickettsii by the tick A. sculptum. All attempts to control tick infestations in environments where there are capybaras have been based on either removing these animals or placing fences around areas frequented by capybaras in an attempt to isolate them from people who visit parks [37] or placing horses treated with ectoparasiticides in those areas (acting as traps) [38].

However, the results obtained have shown that the control of spotted fever is highly complex because of the many factors involved, requiring strategic control [39]. Therefore, actions are needed to enable population control of capybaras, environmental control of the evolutionary forms of A. sculptum, isolation of the most critical areas of parks to minimize human contact with ticks and, last but not least, the search for tools that enable tick control at the time they are parasitizing capybaras.

The topical application of products with acaricidal effect on capybaras is unfeasible because of the need to capture these animals and the fact they remain in the water for many hours. Based on the satisfactory results obtained in this study, combined with methods already employed to control ticks in free-living rodents, our results allow future tests with the use of fluazuron in paraffin blocks (feed cubes) to control the tick A. sculptum in capybaras.


The results of this study indicate that the plasma availability of FLU administered orally in guinea pigs is effective against engorged A. sculptum larvae, bringing perspectives for the development of palatable feed cubes containing FLU for control of A. sculptum on free-living capybaras and also to prevent BSF in areas where capybaras have been shown to play a primary role.

Availability of data and materials

Supporting data for the conclusions of this article are included within the article and its additional files. The raw datasets used and analyzed during this study are available upon reasonable request.


  1. Nava S, Beati L, Labruna MB, Cáceres AG, Mangold AJ, Guglielmone AA. Reassessment of the taxonomic status of Amblyomma cajennense with the description of three new species, Amblyomma tonelliae n. sp., Amblyomma interandinum n. sp. and Amblyomma patinoi n. sp., and reinstatement of Amblyomma mixtum, and Amblyomma sculptum (Ixodida: Ixodidae). Ticks Tick Borne Dis. 2014;5:252–76.

    Article  Google Scholar 

  2. Martins TF, Barbieri ARM, Costa FB, Terassini FA, Camargo LMA, Peterka CRL, et al. Geographical distribution of Amblyomma cajennense (sensu lato) ticks (Parasitiformes: Ixodidae) in Brazil, with description of the nymph of A. cajennense (sensu stricto). Parasit Vectors. 2016;9:1–14.

    CAS  Article  Google Scholar 

  3. Campos-Krauer JM, Wisely SM. Deforestation and cattle ranching drive rapid range expansion of capybara in the Gran Chaco ecosystem. Glob Change Biol Bioenergy. 2011;17:206–18.

    Article  Google Scholar 

  4. Vucetich MG, Deschamps CM, Olivares AI, Dozo MT. Capybaras, size, shape, and time: a model kit. Acta Palaeontol Pol. 2005;50:259–72.

    Google Scholar 

  5. Ferraz KM, Manly B, Verdade LM. The influence of environmental variables on capybara (Hydrochoerus hydrochaeris: Rodentia, Hydrochoeridae) detectability in anthropogenic environments of southeastern Brazil. Popul Ecol. 2010;52:263–70.

    Article  Google Scholar 

  6. Oliveira SV, Guimarães JN, Reckziegel GC, Neves BMC, Araújo-Vilges KM, Fonseca LX, et al. An update on the epidemiological situation of spotted fever in Brazil. J Venom Anim Toxins Incl Trop Dis. 2016;22:1–8.

    Article  Google Scholar 

  7. Szabó MPJ, Pinter A, Labruna MB. Ecology, biology and distribution of spotted—fever tick vectors in Brazil. Front Cell Infect Microbiol. 2013;3:1–9.

    Article  Google Scholar 

  8. Junquera P, Hosking B, Gameiro M, Macdonald A. Benzoylphenyl ureas as veterinary antiparasitics. An overview and outlook with emphasis on efficacy, usage and resistance. Parasite. 2019;26:1–33.

    Article  Google Scholar 

  9. Rodrigues VS, Pina FTB, Barros JC, Garcia MV, Andreotti R. Carrapato-estrela (Amblyomma sculptum): ecologia, biologia, controle e importância. MAPA. 2015;132:1–10.

    Google Scholar 

  10. Marchesini P, Barbosa ALF, Franco C, Novato T, Sanches MNG, Carvalho MG, et al. Activity of the extract of Acmella oleracea on immature stages of Amblyomma sculptum (Acari: Ixodidae). Vet Parasitol. 2018;254:147–50.

    Article  Google Scholar 

  11. Ferreira TP, Cid YP, Alves MCC, Santos GCM, Avelar BR, Freitas JP, et al. In vitro acaricidal activity of Ocimum gratissimum Essential Oil on Rhipicephalus sanguineus, Amblyomma sculptum and Rhipicephalus microplus larvae. Rev Virtual Quím. 2019;11:1604–13.

    CAS  Article  Google Scholar 

  12. Borges DA, Cid YP, Avelar BR, Ferreira TP, Campos DR, Santos GCM, et al. In vitro acaricidal activity of different ectoparasiticide classes against Amblyomma sculptum larvae. Rev Bras Parasitol Vet. 2020;29:1–7.

    Article  Google Scholar 

  13. Taylor MA, Coop RL, Wall RL. Parasitologia Veterinária. 3rd ed. Rio de Janeiro: Guanabara Koogan; 2010.

    Google Scholar 

  14. Pener MP, Dhadialla TS. An overview of insect growth disruptors; applied aspects. Adv In Insect Phys. 2012;43:1–162.

    Article  Google Scholar 

  15. Graf JF. The role of insect growth regulators in arthropod control. Parasitol Today. 1993;9:471–4.

    CAS  Article  Google Scholar 

  16. Reck J, Klafke GM, Webster A, Dall’ Agnol B, Scheffer R, Souza UA, et al. First report of fluazuron resistance in Rhipicephalus microplus: a field tick population resistant to six classes of acaricides. Vet Parasitol. 2014;201:128–36.

    CAS  Article  Google Scholar 

  17. Gomes LVC, Lopes WDZ, Cruz BC, Teixeira WF, Felippelli G, Maciel WG, et al. Acaricidal effects of fluazuron (2.5 mg/kg) and a combination of fluazuron (1.6 mg/kg) + ivermectin (0.63 mg/kg), administered at different routes, against Rhipicephalus (Boophilus) microplus parasitizing cattle. Exp Parasitol. 2015;153:22–8.

    CAS  Article  Google Scholar 

  18. Lopes WDZ, Chiummo RM, Vettorato LF, Rodrigues DC, Sonada RB. The effectiveness of a fixed-dose combination pour-on formulation of 1.25% fipronil and 2.5% fluazuron against economically important ectoparasites and associated pharmacokinetics in cattle. Parasitol Int. 2017;66:627–34.

    CAS  Article  Google Scholar 

  19. Pasay C, Rothwell J, Mounsey K, Kelly A, Hutchinson B, Miezler A, et al. An exploratory study to assess the activity of the acarine growth inhibitor, fluazuron, against Sarcoptes scabei infestation in pigs. Parasit Vectors. 2012;5:1–4.

    Article  Google Scholar 

  20. Slowik TJ, Lane RS, Davis RM. Field trial of systemically delivered arthropod development-inhibitor (fluazuron) used to control woodrat fleas (Siphonaptera: Ceratophyllidae) and ticks (Acari: Ixodidae). J Med Entomol. 2001;38:75–84.

    CAS  Article  Google Scholar 

  21. Davis RM, Cleugh E, Smith RT, Fritz CL. Use of a chitin synthesis inhibitor to control fleas on wild rodents important in the maintenance of plague, Yersinia pestis, in California. J Vector Ecol. 2008;33:278–84.

    Article  Google Scholar 

  22. Ferreira TP, Lima IP, Magalhães VDS, Avelar BR, Oliveira G, Scott FB, et al. Development and validation of a bioanalytical method to measure fluazuron in bovine plasma and its application in pharmacokinetic studies. Rev Virtual Quím. 2019;11:1067–79.

    CAS  Article  Google Scholar 

  23. Heyne H, Elliott EGR, Bezuidenhout JD. Rearing and infection techniques for Amblyomma species to be used in heartwater transmission experiments. Onderstepoort J Vet Res. 1987;54:461–71.

    CAS  PubMed  Google Scholar 

  24. Hadani A, Cwilich R, Rechav Y, Dinur Y. Some methods for the breeding of ticks in the laboratory. Refu Vet. 1969;26:87–100.

    Google Scholar 

  25. Ayres M, Ayres J, Ayres DL, Santos AS. BioEstat 5.3: aplicações estatísticas nas áreas das ciências biológicas e médicas. Belém: Sociedade Civil Mamirauá; 2011.

    Google Scholar 

  26. Sampaio IB. Estatística aplicada a experimentação animal. 4th ed. Belo Horizonte: FEPMVZ; 2015.

    Google Scholar 

  27. Heatle JJ, Russell KE. Exotic animal laboratory diagnosis. In: Hokamp J, Chiacchior RG, Matushima ER, editors. Capybaras (Hydrochoerus hydrochaeris). Hoboken: Wiley; 2020. p. 145–54.

    Google Scholar 

  28. Oliveira PR, Calligaris IB, Roma GC, Bechara GH, Pizano MA, Mathias MIC. Potential of the insect growth regulator, fluazuron, in the control of Rhipicephalus sanguineus nymphs (Latreille, 1806) (Acari: Ixodidae): Determination of the LD95 and LD50. Exp Parasitol. 2012;131:35–9.

    Article  Google Scholar 

  29. Calligaris IB, Oliveira PR, Roma GC, Bechara GH, Camargo-Mathias MI. Action of the insect growth regulator fluazuron, the active ingredient of the acaricide Acatak®, in Rhipicephalus sanguineus nymphs (Latreille, 1806) (Acari: Ixodidae). Microsc Res Tech. 2013;76:1177–85.

    CAS  Article  Google Scholar 

  30. Oliveira PR, Calligaris IB, Nunes PH, Bechara GH, Camargo-Mathias MI. Fluazuron-induced morphological changes in Rhipicephalus sanguineus Latreille, 1806 (Acari: Ixodidae) nymphs: An ultra-structural evaluation of the cuticle formation and digestive processes. Acta Trop. 2014;133:45–55.

    Article  Google Scholar 

  31. Allen JR. Tick resistance: basophils in skin reactions of resistant guinea pigs. Int J Parasitol. 1973;3:195–200.

    CAS  Article  Google Scholar 

  32. Wikel SK, Allen JR. Acquired resistance to ticks. I. Passive transfer of resistance. Immunology. 1976;30:311–6.

    CAS  PubMed  PubMed Central  Google Scholar 

  33. Wikel SK. Acquired resistance to ticks. Am J Trop Med Hyg. 1979;28:586–90.

    CAS  Article  Google Scholar 

  34. Brown SJ, Askenase PW. Cutaneous basophil responses and immune resistance of guinea pigs to ticks: passive transfer with peritoneal exudate cells or serum. J Immunol. 1981;127:2163–7.

    CAS  PubMed  Google Scholar 

  35. Szabó MPJ, Mukai LS, Rosa PCS, Bechara GH. Differences in the acquired resistance of dogs, hamsters, and guinea pigs to repeated infestations with adult ticks Rhipicephalus sanguineus (Acari: Ixodidae). Braz J Vet Res Anim Sci. 1995;32:43–50.

    Article  Google Scholar 

  36. Flajs VC, Grabnar I. Ivermectin pharmacokinetics. Slov Vet Res. 2002;39:167–78.

    Google Scholar 

  37. Pereira HFA, Esto MR. Biologia e manejo de capivaras (Hydrochoerus hydrochaeris) no Parque Estadual Alberto Löfgren, São Paulo. Brasil Rev Inst Florest. 2007;19:55–64.

    Google Scholar 

  38. State of Minas Gerais, 2019. Accessed 06 July 2021.

  39. Durães LS, Bitencourth K, Ramalho FR, Nogueira MC, Nunes EDC, Gazêta GS. Biodiversity of potential vectors of rickettsiae and epidemiological mosaic of spotted fever in the State of Paraná. Brazil Public Health Front. 2021;9:161.

    Google Scholar 

Download references


The authors would like to thank Dr. Silvana Gonçalves de Paula for the contributions to improving our paper.


This study was supported by the Foundation to Support Technological Research (Fundação de Apoio à Pesquisa Tecnológica, FAPUR) at the Federal Rural University of Rio de Janeiro, the Office to Coordinate Improvement of Higher Education Personnel (Coordenação de Aperfeiçoamento Pessoal de Nível Superior, CAPES) and the National Council for Scientific and Technological Development (Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq).

Author information

Authors and Affiliations



DAB: Methodology, writing - review and editing, YPC: Methodology, writing - review and editing, VDM: Methodology, MCCA: Methodology, writing - editing, TPF: Methodology, IVB: Methodology, EASL: Methodology, JPF: Methodology, FBS: Funding acquisition, Supervision, writing - review and editing. All the authors read and approved the final manuscript.

Corresponding author

Correspondence to Debora Azevedo Borges.

Ethics declarations

Ethics approval and consent to participate

All the procedures on animals were approved by the Ethics Committee of the Veterinary Institute of the Federal Rural University of Rio de Janeiro (code 575713121; 96044140721 and 7699190418).

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Borges, D.A., Cid, Y.P., Magalhães, V.d. et al. Fluazuron orally administered to guinea pigs: pharmacokinetic and efficacy against Amblyomma sculptum. Parasites Vectors 15, 198 (2022).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:


  • Insect growth regulators
  • Tick control
  • Cavia porcellus
  • Ectoparasites
  • Capybaras
  • Bioavailability