Intranasal clotrimazole spray 1% associated with oral itraconazole for nasal feline sporotrichosis: a case series

Abstract
Feline sporotrichosis is a major clinical problem among cats in Brazil and is also a neglected, but important,
public health issue, due to its zoonotic potential. The nasal clinical form of the disease is particularly challenging,
having treatment refractoriness and clinical signs relapse as common features. This case series study aimed
to preliminarily describe the effects of the azolic antifungal drug, clotrimazole, as a topical 1% solution spray,
together with per os itraconazole on inducing disease remission, as well as treatment tolerability and safety.
Medical records of the Feline Medicine Service from the Universidade Federal Rural do Rio de Janeiro were
reviewed, and 7 feline patients met the inclusion criteria (confirmatory diagnostic reached, available follow-up
records, and use of intranasal clotrimazole 1% solution –1 spray per nostril every 24 hours– as adjunctive therapy
to itraconazole – 100 mg/cat per os every 24 hours). Among these, 4 had a history of treatment refractoriness
done until then. Follow-up records included clinical evaluation, along with complementary tests and owner
reports on tolerability and occurrence of adverse reactions. All patients have undergone clinical remission within
60 days. Tolerability were satisfactory, and adverse reactions were only found on complementary tests (hepatic
enzyme elevation), without clinical repercussion. The intranasal use of 1% clotrimazole solution has shown as
a promising adjunctive therapy to itraconazole for feline nasal sporotrichosis, even in previous refractory cases.
Keywords: azolic antifungal, subcutaneous mycosis, Sporothrix brasiliensis, nasal granuloma.

Resumo
A esporotricose felina é um dos principais problemas clínicos entre os gatos no Brasil. É também um problema
de saúde pública negligenciado, mas importante, devido ao seu potencial zoonótico. A forma clínica nasal da
doença é particularmente desafiadora, sendo a refratariedade ao tratamento e a recidiva dos sinais clínicos
características comuns. Este estudo de série de casos teve como objetivo descrever preliminarmente o efeito
da infusão intranasal do antifúngico azólicos clotrimazol, na forma de solução “spray” a 1%, com itraconazol
dado via oral, na indução da remissão da doença em pacientes felinos, bem como a tolerabilidade e segurança
do tratamento. Os registros médicos do Serviço de Medicina Felina da Universidade Federal Rural do Rio de
Janeiro foram revisados, e 7 pacientes felinos atenderam aos critérios de inclusão (diagnóstico confirmatório
alcançado, prontuários de acompanhamento disponíveis e uso de solução intranasal de clotrimazol 1% –1 borrifada
por narina a cada 24 horas– como terapia adjuvante ao itraconazol –100 mg / gato por via oral a cada 24 horas).
Destes, 4 tinham história de refratariedade ao tratamento realizado até então. Os registros de acompanhamento
incluíram avaliação clínica, realização de testes complementares e relatórios dos responsáveis pelos animais
acerca da tolerabilidade e ocorrência de efeitos adversos. Todos os pacientes apresentaram remissão clínica
em até 60 dias. A tolerabilidade e a segurança foram satisfatórias, sendo encontrados efeitos adversos apenas
em exames complementares (elevação das enzimas hepáticas), sem repercussão clínica. O uso tópico de
solução de clotrimazol a 1% mostrou-se uma promissora terapia adjuvante ao itraconazol dado por via oral
para o tratamento da esporotricose nasal felina, mesmo em casos previamente refratários.
Palavras-chave: antifúngico azólico, micose subcutânea Sporothrix brasiliensis, granuloma nasal.

Introduction
Sporotrichosis is a subcutaneous zoonotic fungal disease that is caused by Sporothrix spp.
and has become endemic in Brazil during the last decades (Gremião et al., 2021). Epidemiologically,
cats play an important role in this disease cycle since their lesions present a high burden of yeast
cells (Souza et al., 2018). Additionally, infected cats may easily transmitte the fungi by scratches
and bite wounds to other cats because of their territorial and predatory behavior, and to humans
due to cat-human bond (Montenegro et al., 2014).
In the southeast region, more specifically in the state of Rio de Janeiro, sporotrichosis has
reached hyperendemic proportions, with Sporothrix brasiliensis as the most prevalent species
(Rodrigues et al., 2020). Many studies have described this species’ features, which is now known
for its impressive adaptation for parasitism, virulence in both feline and human patients, and
widespread resistance to azoles the first-line drugs used for this infection (Nakasu et al., 2021).
In the feline patient, the treatment for nasal sporotrichosis is particularly challenging, with
many cases being refractory to standard therapies (i.e., per os itraconazole ± potassium iodide)
(Nakasu et al., 2021). The reason is not fully understood; however, according to Malik et al. (2004),
this region in the cat is relatively poorly vascularized, which may prevent systemic drugs from
reaching it in appropriate concentrations. Additionally, evidence showed that this fungus can
invade bone and cartilage tissues and infect osteoclasts in this region, which further complicates
the complete healing (Gremião et al., 2015).
Clotrimazole is an azolic antifungal that is highly effective against S. brasiliensis isolates in vitro
(Gagini et al., 2017). In vivo, it has been used topically by intravesical infusion in a cat with cystitis and
candiduria secondary to diabetes mellitus (Toll et al., 2003) and by intranasal infusion in two cats with
nasal aspergillosis (Furrow & Groman, 2009), both with good efficacy. Therefore, this case series aimed
to describe a series of cases where the the azolic antifungal drug clotrimazole were used as a intranasal
solution spray at 1% together with per os itraconazole for treating the nasal form of feline sporotrichosis.

Materials and methods
This case series is based on the medical records of cats presented to the Feline Medicine Service at
the Veterinary Hospital from the Universidade Federal Rural do Rio de Janeiro-UFRRJ (Seropédica-Rio
de Janeiro) between 2018 and 2021 with nasal sporotrichosis (lesions extending from the nasal
bridge to the intern mucosa). Included cases were those with a confirmatory diagnosis that was
reached by fungal culture (± other laboratory tests such as cytology and serology); the veterinarian
in charge prescribed an intranasal infusion of clotrimazole spray (1% clotrimazole in sodium chloride
solution; Grupo TudoDVet Farmácia Veterinária ®
; one spray in each nostril at approximately 1 mL
per nostril, SID) (Figure 1) as adjunctive therapy to per os itraconazole (100 mg/cat PO SID); with
follow-up records of a minimum of 30 days from the beginning of drug usage; and with posttreatment
follow-up evaluation times. In all cases, written consent was obtained from the owner.

The clotrimazole spray intranasal infusion was performed by introducing the applicator tip
through the nostril and pulling the valve one time per nostril, as shown in Figure 1.
The collected data included gender, age, neutering and retroviral status, body weight, lifestyle,
signalment, diagnostic methods used to confirm infection, previous treatments (including drug(s)
utilized and duration), and complementary tests. Cases were considered refractory if the previous
treatment had not induced any clinical improvement for >3 months. Follow-up data were also
collected, including reported adverse reactions by owners, clinical evaluation, and complimentary
exam findings. Patients were considered in clinical remission if clinical signs, such as nasal bridge
bulging, stertor, sneezing, edema, and ulceration, were significantly atenuated within 60 days.

Results
A total of 7 cases met the inclusion criteria, of which 4 cases (cases 1, 3, 6, and 7) had a history of
treatment refractoriness used until then. Patient data regarding age, gender, weight, signalment,
lifestyle, retroviral, and castration status, as well as the performed diagnostic tests, adverse
reactions, and treatment outcomes are shown in Table 1.
This case series patients’ group included 4 males and 3 females. All animals were castrated
and kept strictly indoors except for cats 1 and 6. The mean age and body weight were 5.14 years
old and 4.14 kg, respectively. Diagnostic methods used to confirm infection included fungal
isolation for all seven cases, quantitative serology for anti-SsCBF IgG antibodies on cases 4, 5, and
7 (titers of 1:1600, 1:1600, and 1:12800, respectively; cutoff titer of 1:400) and cytology on cases
1, 2, and 3. The mean previous treatment duration time was 12.2 months (1–48 months). All the
cats have received per os itraconazole (25–100 mg/cat), and potassium iodide (5–50 mg/kg) was
also given in cases 3, 4, 6, and 7. Other therapies included fluconazole (case 3), famciclovir, human
recombinant-interferon, enrofloxacin, N-acetylcysteine (case 5), amoxicillin (case 2), and topical
ketoconazole cream (case 4).
Treatment efficacy was evaluated by clinical remission of lesions and signalment, such as
nasal bridge bulging, ulceration, edema, airway flow obstruction, sneezing, respiratory stertor,
and nasal discharge. Treatment outcomes are presented in Table 1. The mean treatment duration
was 3.4 months (2–6 months). In most patients, clinical sign remission occurred within 60 days,
whereas in only 30 days in case 3 (Figure 2).
Except for salivation following accidental oral administration of clotrimazole, no other adverse
reactions were reported by owners. The complementary tests revealed that 3 patients (cases
3, 4, and 6) showed mild to moderate alanine-aminotransferase elevation (ALT: 94–324 U/L;
reference range: 5–60 U/L) and 2 (cases 4 and 6) showed mild alkaline phosphatase elevations
(ALP: 101–116 UI/L; reference range: >90 UI/L) at some treatment points. However, the clinical signs
of hepatic injury (e.g., vomiting, weight loss, and inappetence) were absent according to these
owners. Other biochemical parameters (such as creatinine, blood urea nitrogen, and albumin)
were normal in all cats, as well as the complete blood count (CBC).
All but one owner reported no difficulty with therapy administration. The owner who found
infusing the drug difficult reported struggles with patient restraints, and on some occasions, the
drug was infused orally instead because of the cat’s reluctance. With this, salivation was observed.
The mean follow-up time after treatment discontinuation was 54 days (range: 16–93 days), during
which no relapses occurred.

Discussion
Sporotrichosis is a major health problem in Brazil’s feline population and has zoonotic implications,
which also configures it into a public health issue. Gremião et al. (2021) stated that early and
successful treatment of feline sick patients is the key to breaking this agent cycle and preventing
new infections. However, refractoriness is a common finding in cats with nasal sporotrichosis,
which makes this specific clinical form very frustrating for both veterinarians and owners. Previous
studies have demonstrated the efficacy of alternative therapies in these refractory cases, such as
the use of cryosurgery and intralesional amphotericin B (Gremião et al., 2009; Souza et al., 2016).
However, these options can be expensive due to the geographic distribution of sporotrichosis
in our country, where most patients come from poor families, therefore prohibitive for many

owners (Gutierrez-Galhardo et al., 2015; Sanchotene et al., 2015). Furthermore, some owners
will not consent to submit their cats to these procedures because of their inherent invasiveness.
However, as revealed in this case series, compounded 1% clotrimazole spray is a cheaper and
non-invasive alternative that may be added in cases with little effect from the standard therapy.
Similarly to itraconazole, this drugs’ mechanism of action consist in the sterol 14a-demethylase
enzyme (CYP51) inhibition, interefering, thus, with the ergosterol (main component of the fungus
plasmatic membrane) synthesis (Ferreira et al., 2020). Gagini et al. (2017) revealed that clotrimazole
is highly efficient against S. brasiliensis isolates in vitro, either alone or associated with itraconazole;
however, in vivo studies were lacking until the present. Other studies have already reported the
successful use of intranasally delivered clotrimazole for fungal rhinitis in cats (Barrs et al., 2012;
Furrow & Groman, 2009; Tomsa et al., 2003). The etiological agent in those was Aspergillus sp.,
with differences regarding therapeutic protocols (i.e., patients were anesthetized and clotrimazole
was infused through a catheter inserted intranasally); however, they revealed that this drug may
be well-tolerated and safe for this route in feline patients.
Nevertheless, the employed clotrimazole solution in at least one of those previous reports
contained isopropanol and propylene glycol, which potentially cause pharyngeal edema and
inflammation. Tomsa et al. (2003) reported local irritation after clotrimazole infusion in one
cat and, therefore, recommended the placement of an enteral feeding tube to prevent it from
stopping eating. However, this was not reported in patients described herein, possibly, due to the
composition of the used clotrimazole solution in these patients, which only contains clotrimazole
in sodium chloride solution, according to the manufacturer. Additionally, differences were found
in the drug administration and volume between our patients and the ones from these studies,
wherein drug delivery was accomplished by infusion of 8–10 mL of clotrimazole solution per nostril in the latter, whereas only 1 spray pressing (approximately 1 mL/nostril) inside the applied
cat nostril in our study.
At the follow-up appointments, generally performed every 30 days after treatment initiation,
blood samples for CBC and serum biochemistry were collected to assess the therapy tolerability.
Some cats showed mild elevations in hepatic enzymes, such as ALT and ALP. Possibly, such
alterations were due to oral itraconazole administration, which is known to cause hepatic injury
(Gremião et al., 2021; Pereira et al., 2010; Reis et al., 2016). However, they were not accompanied
by clinical signs, such as inappetence, vomiting, and weight loss, as expected in hepatotoxicity.
In all these cases, hepatic enzymes were decreased following the institution of hepaprotective
therapy (silymarin at 90 mg/cat PO once a day). Nonetheless, more studies are needed to verify
the issue of hepatotoxicity in topical clotrimazole therapy.
Our case series had median treatment duration of 12.2 months before presentation. This is
considerably longer compared to studies that evaluate other alternative therapies to refractory
sporotrichosis, such as intralesional amphotericin B or cryosurgery (8 and 3.59 months,
respectively) (Gremião et al., 2009; Souza et al., 2016). However, the effectiveness was similar.
This finding is encouraging, as this could mean that 1% clotrimazole spray may be efficient even
in long-lasting refractory cases, which comprise a great portion of feline patients with nasal
sporotrichosis. The authors believe that this is most likely because the topical application of the
drug produces high concentrations within nasal tissues, thus increasing its ability to mitigate the
infection, similar to Sharman and Mansfield (2012) in their review concerning topical therapies
for intranasal mycosis in dogs.
Noteworthy, a significant limitation of this therapy is that the owner must handle the patient
daily to intranasally infuse the drug. This may represent a zoonotic risk, which is even more
significant if the person in charge of drug administration is immunocompromised (e.g., human
immunodeficiency virus-positive and oncologic patients) (Chakrabarti et al., 2015). Additionally,
some cats may not tolerate restraint during drug application, and owners might find it difficult
to adapt the therapy. In this study, only one owner reported struggling with drug administration,
and were accidentally administered orally on some occasions, eliciting salivation. This probably
reflects the bitter taste of the drug since such an event did not happen when it was properly
infused. All the other owners described ease at administration and good acceptance by their cats.
However, careful handling, and probably, the help of a second person is advisable both to ease
the drug infusion procedure and reduce the likelihood of zoonotic transmission, even though the
latter is considered low, as yeast cells burden is drastically decreased once systemic and topical
treatments are adopted (Gremião et al., 2021). The authors recommend discussing the risks with
owners before treatment prescription.
The in vivo utilization of clotrimazol for treating feline sporotrichosis due to S. brasiliensis
has never been described before. In this case series, its intranasal administration daily togheter
with oral itraconazole has shown as a valuable therapeutic option to induce the disease’s clinical
remission. In order to further evaluate the efficacy of this therapy, as well as its safety, adverse
reactions and tolerability, prospective controlled studies are warranted.
In conclusion, the use of 1% clotrimazole solution for intranasal infusion together with oral
itraconazole has determined the clinical remission of feline nasal sporotrichosis in the patients
described and may be viewed as a promising therapy modality to be considered in cases where
the traditional oral therapy alone shows little effect on nasal sporotrichosis treatment.

Acknowledgements
The authors thank the drug’s manufacturer “TudoDVet” for accepting to formulate the drug
and also for providing all information regarding the process.

Ethics statement
All procediments were consented by the animals’ owners.

Financial support
JPS – Received scholarship from MEC (Ministério da Educação). CRGRS – Received scholarship
from CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior). ASS and HJMS – None.

Conflicts of interests
JPS, CRGRS, ASS, e HJMS – No conflict of interest.
Authors’ contributions
JPS, HJMS – Development of methodology; preparation and writing the initial draft. JPS, CRGRS,
ASS a HJMS – Writing, Review and Editing manuscript.

Availability of complementary results
Please, contact the correspondent author for complementary information on this subject.
The study was carried out at the Hospital Veterinário de Pequenos Animais – HVPA, from the
Universidade Federal Rural do Rio de Janeiro, Campus Seropédica, RJ, Brasil.

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