2.2. Dimethyl sulfoxide (DMSO)

The delegate's final decision under regulation 42ZCZR of the Therapeutic Goods Regulations 1990 (the Regulations) is to amend the current Poisons Standard in relation to dimethyl sulfoxide as follows:

Implementation date: 1 February 2019

Reasons:

The delegate has amended the Schedule 4 proposal in the interim decision to ensure consistency with restrictions that apply to the use of DMSO in listed medicines, and confirms that the reasons for the final decision align with the reasons for the interim decision.

The matters under subsection 52E (1) of the Therapeutic Goods Act 1989 considered relevant by the delegate for the decision include:

1. the risks and benefits of the use of a substance:

   DMSO has a number of therapeutic uses due to its low toxicity, although it is an eye and skin irritant in undiluted form. However, as a carrier or universal solvent that enhances the skin penetration of other substances, DMSO enhances their therapeutic and toxic effects.

2. the purposes for which a substance is to be used and the extent of use of a substance:

   DMSO is widely used as a commercial solvent, and has many applications in agricultural and veterinary products. It is also found in a number of human therapeutic preparations, including for dermal use, at concentrations greater than 10%. The amendment to the Schedule 4 entry allows consistency with restrictions that apply to the use of DMSO in listed medicines. DMSO is prohibited in cosmetic products in the EU (Regulation (EC) No 1223/2009 – Annex II).

   Only non-therapeutic uses of DMSO are covered by the proposed Schedule 6 exemption.

3. the toxicity of a substance:

   DMSO is of low acute toxicity but is considered both a skin and eye irritant at concentrated doses. It is a mild irritant to skin and eyes when diluted (less than 66 percent solutions). DMSO is not considered to be genotoxic or carcinogenic, nor to produce reproductive or developmental toxicities. In experimental animals, very high intravenous doses produced toxic effects in the liver and kidney, but no adverse effects on the liver or kidney have been observed in humans. Long-term oral or dermal administration produces only slight toxicity. The proposed exposure to DMSO is not a health concern.

   DMSO enhanced dermal penetration of other compounds and may thereby enhance toxicity of these compounds.

4. the dosage, formulation, labelling, packaging and presentation of a substance:
   • Schedule 6 products require labelling and packaging in accordance with the Poisons Standard. Labelling of unscheduled products is the responsibility of the manufacturer / supplier.
   • The acute toxicity data supports a cut-off for DMSO in Schedule 6. Although the toxicity data presented by the applicant corresponds to DMSO concentrations of 60% and greater, 10% is a conservative and therefore reasonable estimate to ensure no significant toxicity in exempt preparations.
5. the potential for abuse of a substance:
   • Scheduling history reports abuse in the 1980s but no recent reports and risk appears low.
6. any other matters that the Secretary considers necessary to protect public health:
   • The intention of the Schedule 4 amendment is to align this entry with the requirements of the Therapeutic Goods (Permissible Ingredients) Determination No. 3 of 2018.