Scheduling delegate's interim decisions and invitation for further comment: ACCS/ACMS, November 2016

Scheduling medicines and poisons

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2 February 2017

1.7 Abamectin

Part A - Interim decisions on matters referred to an expert advisory committee (November 2016)

Advisory Committee on Chemicals Scheduling (ACCS #18)

1.7 Abamectin

Referred scheduling proposal

An application was submitted by the Australian Pesticides and Veterinary Medicines Authority (APVMA) to amend the Schedule 5 entry for abamectin to accommodate preparations containing 0.05 per cent or less of abamectin in a gel formulation.

Scheduling application

General application.

The applicant's proposed amendments to the Poisons Standard are as follows:

Schedule 5 - Amend Entry

ABAMECTIN:

  1. in preparations, for internal use for the treatment of animals, containing 1 per cent or less of abamectin; or
  2. in preparations containing 0.05 per cent or less of abamectin formulated as ready to use cockroach bait gel in application syringes containing no more than 100 g of product.

The applicant's reasons for the request are:

  • The product, PestXpert DIY Pest Control Like The Professionals Cockroach Bait, contains 0.5 g/kg (0.05%) abamectin in a preparation for pesticidal use that is not for internal use for the treatment of animals and would therefore be considered a Schedule 6 poison. Sumitomo Chemical Australia Pty Ltd is seeking a new entry in Schedule 5 for preparations containing 0.05% of abamectin, or less.
  • The other active constituent in the product, pyriproxyfen, is included in Appendix B of the Poisons Standard, based on its low toxicity profile, when used as a pesticide.
  • Based on acute toxicity studies using a surrogate formulation with the same abamectin content (0.05%), the product is considered to have low acute oral toxicity (LD50 >5000 mg/kg bw) and low acute dermal toxicity (LD50 >5000 mg/kg bw). The product was a slight eye irritant but not a skin irritant.
  • Given the proposed product formulation, packaging and recommended use pattern, oral exposure is not expected. Nonetheless, if accidental ingestion by a child (20 kg bw) of the product containing 0.05% abamectin from a ready to use syringe was to occur, it would be well under the ARfD for abamectin.
  • Minimal exposure is expected from the application of the ready to use gel formulation available in 10-100 g sealed syringes. Bystander exposure is considered unlikely.
  • The effect of skin sensitisation by the product can be adequately managed through the labelling statements which recommend that applicators wear gloves.
Current scheduling status

Abamectin is currently listed in Schedules 7, 6 and 5 and is also included in Appendix J, Part 2 as follows:

Schedule 7

ABAMECTIN except when included in Schedule 5 or 6.

Schedule 6

ABAMECTIN:

  1. in preparations for pesticidal use containing 4 per cent or less of abamectin except when included in Schedule 5; or
  2. in slow-release plastic matrix ear tags for livestock use containing 1 g or less of abamectin.

Schedule 5

ABAMECTIN in preparations, for internal use for the treatment of animals, containing 1 per cent or less of abamectin.

Appendix J, Part 2 - ABAMECTIN

Condition: 1 (not to be available except to authorised or licensed persons).

Relevant scheduling history

Abamectin has been considered several times by the committee, both on its own, and in combination with other substances.

Abamectin was first considered in November 1984 as avermectin. In November 1984, the Poisons Schedule (Standing) Committee (PSC) considered scheduling of a 1 per cent avermectin B1 (a synonym for abamectin) injection to be used as an antiparasitic agent in animals. Based on toxicity, PSC decided to include this substance in Schedule 7. However, the PSC also noted the intent to only market a sealed container product for use with automated injection equipment and agreed to a Schedule 6 cut-off for such preparations when included in 10 mL or less injections.

In May 1992, the Drugs and Poisons Schedule Standing Committee (NDPSC) agreed to a request to change the name of avermectin B1 in the schedule entries to abamectin, noting that this was the name approved by the Standards Association of Australia (now called Standards Australia).

In August 1994, the NDPSC decided to include emulsifiable concentrate formulations containing abamectin at 18 g/L or less in Schedule 6.

In August 1995, NDPSC agreed to include ≤ 1 per cent abamectin for animal internal use in Schedule 5.

In June 2008, the NDPSC decided also to include slow-release plastic matrix ear tags for livestock use containing 1 g or less of abamectin in Schedule 6.

In October 2009, the NDPSC considered whether preparations for pesticidal use containing 0.0015 per cent or less of abamectin were consistent with the Schedule 5 criteria. It was agreed that although low concentration of abamectin were likely to be less hazardous, because insufficient data had been provided to allay the concern regarding the high acute oral, dermal and inhalation toxicity of abamectin, it was decided that the existing scheduling was appropriate.

Following recommendation of the March 2013 Advisory Committee on Chemicals Scheduling (ACCS), Schedule 6 cut-off for abamectin in preparations for pesticidal use has been increased from 2 per cent to 4 per cent or less of abamectin, except when included in Schedule 5, or in slow-release plastic matrix ear tags for livestock use containing 1 g or less of abamectin.

Australian regulatory information

As an AgVet chemical, abamectin is subject to labelling requirements according to the First Aid Instruction and Safety Directions (FAISD) Handbook.

Substance summary

Structure of abamectin

Figure 1.7: Structure of abamectin

Table 1.7A: Chemical information
Property Abamectin
CAS name Abamectin: mixture of ≥80% abamectin B1a & <20% abamectin B1b
CAS number

Abamectin: 71751-41-2 containing 65195-55-3 (abamectin B1a) and

65195-56-4 (abamectin B1b).

IUPAC and/or common and/or other names

Abamectin: mixture of

(10E,14E,16E)-(1R,4S,5'S,6S,6'R,8R,12S,13S,20R,21R,24S)-6'-[(S)-sec-butyl]-21,24-dihydroxy-5',11,13,22-tetramethyl-2-oxo-(3,7,19-trioxatetracyclo[15.6.1.14,8.020,24]pentacosa-10,14,16,22-tetraene)-6-spiro-2'-(5',6'-dihydro-2'H-pyran)-12-yl 2,6-dideoxy-4-O-(2,6-dideoxy-3-O-methyl-α-L-arabino-hexopyranosyl)-3-O-methyl-α-L-arabino-hexopyranoside

and

(10E,14E,16E)-(1R,4S,5'S,6S,6'R,8R,12S,13S,20R,21R,24S)-21,22-dihydroxy-6'-isopropyl-5',11,13,22-tetramethyl-2-oxo-(3,7,19-trioxatetracyclo[15.6.1.14,8.020,24]pentacosa-10,14,16,22-tetraene)-6-spiro-2'-(5',6'-dihydro-2'H-pyran)-12-yl 2,6-dideoxy-4-O-(2,6-dideoxy-3-O-methyl-α-L-arabino-hexopyranosyl)-3-O-methyl-α-L-arabino-hexopyranoside.

The following toxicology information was extracted from the Office of Chemical Safety (OCS) human health risk assessment technical report for Abamectin, Pyriproxyfen (product name PestXPert DIY Pest Control Like the Professionals Cockroach Bait).

Table 1.7B: Acute toxicity end-points for a formulated product that was considered by the OCS to be an acceptable surrogate to the proposed product containing 0.05% abamectin and 0.5% pyriproxyfen
Toxicity Species Product containing abamectin
(0.05%)
SPF (2015) Classification
Acute oral toxicity LD50 (mg/kg bw) Rat >5000 N/A
Acute dermal toxicity LD50 (mg/kg bw) Rat >5000 N/A
Acute inhalational toxicity LC50 (mg/m3/4h) No data No data N/A
Skin irritation Rabbit Non-irritant N/A
Eye irritation Rabbit Slight irritant Schedule 5
Skin sensitisation (Buehler Method) Guinea pigs Sensitiser
Pre-meeting public submissions

No pre-meeting submissions were received for abamectin.

Summary of ACCS advice to the delegate

The committee advised that Schedule 5 entry for abamectin in the Poisons Standard be amended to include gel formulations containing 0.05 per cent or less of abamectin as follows:

Schedule 5 - Amend Entry

ABAMECTIN:

  1. in preparations, for internal use for the treatment of animals, containing 1 per cent or less of abamectin; or
  2. in gel formulations containing 0.05 per cent or less of abamectin in applicators containing 50 mg or less of abamectin.

The committee also recommended an implementation date of 1 June 2017.

Members agreed that the relevant matters under Section 52E(1) of the Therapeutic Goods Act 1989 included: (a) risks and benefits of the use of a substance; (c) the toxicity of a substance; and (d) the dosage, formulation, labelling, packaging and presentation of a substance.

The reasons for the advice comprised the following:

  • Abamectin is a skin sensitiser.
  • Abamectin at this concentration and in this dose form has an inferred toxicity profile consistent with Schedule 5 factors, based on a surrogate formulation.
  • Products containing abamectin at this concentration and in this dose form should be labelled to ensure the use of appropriate personal protective equipment.
Delegate's considerations

The delegate considered the following in regards to this proposal:

  • Scheduling proposal
  • ACCS advice
  • Public Submissions received
  • Section 52E of the Therapeutic Goods Act 1989
  • Scheduling Policy Framework (SPF 2015)
  • Other relevant information.
Delegate's interim decision

The delegate's interim decision is to amend the Schedule 5 entry for abamectin to include gel formulations containing 0.05 per cent or less of abamectin.

The proposed Schedule entry is as follows:

Schedule 5 - Amend Entry

ABAMECTIN:

  1. in preparations, for internal use for the treatment of animals, containing 1 per cent or less of abamectin; or
  2. in gel formulations containing 0.05 per cent or less of abamectin in applicators containing 50 mg or less of abamectin.

The proposed implementation date is 1 June 2017.

The matters under subsection 52E (1) of the Therapeutic Goods Act 1989 considered relevant by the delegate included: a) the risks and benefits of the use of the substance; c) the toxicity of the substance; and d) the dosage, formulation, labelling, packaging and presentation of a substance.

The reasons for the recommendation comprised the following:

  • The delegate acknowledges the committee's advice.
  • Abamectin is a skin sensitiser.
  • Abamectin at this concentration and in this dose form has an inferred toxicity profile consistent with Schedule 5 factors, based on a surrogate formulation.
  • Products containing abamectin at this concentration and in this dose form should be labelled to ensure the use of appropriate personal protective equipment.
  • Earliest possible implementation date.

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