Relative bioavailability and comparative clinical efficacy of different ivermectin oral formulations in lambs

Potential of Streptomyces avermitilis: A Review on Avermectin Production and Its Biocidal Effect

Secondary metabolites produced by the fermentation of Streptomyces avermitilis bacterium are powerful antiparasitic agents used in animal health, agriculture and human infection treatments. Avermectin is a macrocyclic lactone with four structural components (A1, A2, B1, B2), each of them containing a major and a minor subcomponent, out of which avermectin B1a is the most effective parasitic control compound. Avermectin B1a produces two homologue avermectins (B1 and B2) that have been used in agriculture as pesticides and antiparasitic agents, since 1985. It has a great affinity with the Cl-channels of the glutamate receptor, allowing the constant flow of Cl- ions into the nerve cells, causing a phenomenon of hyperpolarization causing death by flaccid paralysis. The purpose of this work was to gather information on the production of avermectins and their biocidal effects, with special emphasis on their role in the control of pests and phytopathogenic diseases. The literature showed that S. avermitilis is an important producer of macrocyclic lactones with biocidal properties. In addition, avermectin contributes to the control of ectoparasites and endoparasites in human health care, veterinary medicine and agriculture. Importantly, avermectin is a compound that is harmless to the host (no side effects), non-target organisms and the environment.

Therapeutic advantages of the combined use of closantel and moxidectin in lambs parasitized with resistant gastrointestinal nematodes

The serious widespread development of nematode resistance has motivated the use of combined anthelmintic formulations. However, the advantages/disadvantages of the combined use of anthelmintics require further scientific characterization. The goals of the current trial were a) to characterize the pharmacokinetics of closantel (CLO) and moxidectin (MXD) administered both subcutaneously (sc) and orally either separately or co-administered (CLO + MXD) to lambs; b) to compare the nematodicidal activity of both molecules given individually or co-administered to lambs infected with resistant nematodes. Seventy (70) Corriedale lambs naturally infected with multiple resistant gastrointestinal nematodes were involved in the pharmacokinetic and efficacy trials. The animals were allocated into six groups (n = 10) and treated with either CLO, MXD, or with the CLO + MXD combined formulation by both the oral and sc routes. Additionally, an untreated control group (n = 10) was included for the efficacy trial. The efficacy was estimated by the faecal egg count reduction test (FECRT). Higher systemic exposure of both CLO and MXD was observed after the sc compared to the oral administration in lambs. The combined administration of CLO + MXD did not markedly alter their disposition kinetics. At 13 days post-treatment, the administration of both molecules as a single active principle reached efficacy levels ranging between 80% (MXDoral), 84% (CLOoral), 85% (CLOsc), and 92% (MXDsc). The combined oral and sc treatments reached 99% efficacy. No adverse effects were observed after the combined treatment of CLO + MXD, and their co-administration did not show any adverse pharmacokinetic interaction. The combined effect of CLO + MXD successfully restored the maximum efficacy levels, which were not reached by the individual active ingredients.

[Development of an ivermectin-containing syrup as an extemporaneous preparation for treatment of scabies in children]

BACKGROUND

Oral ivermectin can be used to treat scabies. Evidence for safe and effective use in young children in individual treatment situations has been developed and published. In order to also ensure a body weight-adapted dosage for children, an ivermectin-containing syrup was developed as an extemporaneous preparation.

MATERIALS AND METHODS

Since ivermectin is not available as a pure substance for the formulation, tablets containing active ingredient were used as a basic material for development. The formulation was designed according to pharmaceutical, regulatory and use-oriented criteria. An HPLC (high-pressure liquid chromatography) method was developed and validated to demonstrate chemical stability. In order to facilitate the practical implementation, information on suitable packaging material and application aids was also developed and the formulation was evaluated.

RESULTS

It has been demonstrated that the final formulation produced in the pharmacy was stable and can be stored for 3 weeks. No concerns were raised regarding the tolerability of the syrup formulation. The physicochemical properties and the taste of the formulation allow the intended use as a well-dosed syrup for children.

CONCLUSION

The developed formulation meets the requirements of the Apothekenbetriebsordnung (Pharmacy Work Rules; Section 7 ApBetrO) and enables an exact, body weight-adapted dosage of oral ivermectin in young children. Studies on human pharmacokinetics or clinical studies to demonstrate tolerability and/or efficacy are not available for the formulation.

Molecular confirmation and anthelmintic efficacy assessment against natural trichurid infections in zoo-housed non-human primates

INTRODUCTION

This study aimed to assess Trichuris species infection and evaluate the anthelmintic efficacy of fenbendazole and ivermectin against natural trichurid infections in non-human primates (NHPs), kept at Mahendra Chaudhury (MC) Zoological Park, Chhatbir, India.

MATERIALS AND METHODS

Molecular confirmation of Trichuris infection was carried out using polymerase chain reaction targeting internal transcribed spacer sequences, and anthelmintic efficacy was assessed by fecal egg count reduction test, respectively.

RESULTS

A 710 base pair product confirmed Trichuris species infection in NHPs. Fenbendazole, 10 mg/kg body weight orally for 5 consecutive days and ivermectin, 100 μg/kg body weight orally for 3 alternate days proved effective and showed a maximum fecal egg reduction of 99.20% and 100% (P < .05) at day 7 post-treatment.

CONCLUSIONS

This study highlighted the molecular confirmation of Trichuris species in non-human primates and its management using fenbendazole and ivermectin.

Pharmacokinetic evaluation of different generic triclabendazole formulations in heifers

AIMS

To assess the comparative drug systemic exposure of a reference (RF) and four test (Test I, Test II, Test III and Test IV) formulations of triclabendazole (TCBZ) in heifers.

METHODS

Thirty Holstein heifers were randomly distributed into five groups (n=6 per group). Animals in the RF group received the reference formulation (Fasinex), and those in the other groups received different commercially available TCBZ formulations (Test I, Test II, Test III and Test IV). All treatments were orally administered at 12 mg/kg bodyweight. The concentrations of TCBZ metabolites in plasma between 0 and 168 hours after treatment were quantified by high-performance liquid chromatography (HPLC).

RESULTS

Triclabendazole sulphoxide (TCBZ.SO) and TCBZ-sulphone (TCBZ.SO₂) were the only analytes recovered in plasma. Only the Test I formulation did not differ from the RF for all pharmacokinetic parameters measured for either metabolite (p>0.8). The TCBZ.SO area under the concentration vs. time curve for Test II formulation (268.9 µg.h/mL) was lower, and for Test III (619.9 µg.h/mL) and Test IV (683.4 µg.h/mL) was higher, than the RF (418.1 µg.h/mL) (p<0.005).

CONCLUSION

Based on the currently available bioequivalence criteria, the only test formulation under evaluation that could be considered equivalent to the RF was the Test I formulation, which demonstrated an equivalent systemic exposure for the active TCBZ.SO metabolite. This comparison of TCBZ pioneer and test formulations in cattle raises awareness of the need for further quality control for drug approval in the veterinary pharmaceutical field in many regions of the world.