Oral Ketamine in Australia: Formulations, Clinical Evidence, and Legal Reality

Oral ketamine is an off-label prescription medicine in Australia, used primarily in chronic pain management and some psychiatric research settings. Unlike esketamine nasal spray, which must be administered under hospital supervision, oral ketamine exists as troches or lozenges, allowing patients to use it outside of clinical settings under medical guidance. However, this convenience comes with significant legal restrictions and clinical uncertainties.

Basic Characteristics of Oral Ketamine: Prodrug Metabolism and Lower Bioavailability

The pharmacokinetic profile of oral ketamine determines its fundamental differences from other administration routes. Oral ketamine undergoes extensive hepatic first-pass metabolism, resulting in a bioavailability of approximately 29%, far lower than the 100% achieved with intravenous injection. This means that after oral administration, lower concentrations of active drug reach the systemic circulation, and onset is slower.

However, first-pass metabolism is not entirely disadvantageous. After oral administration, the primary metabolite norketamine reaches higher plasma concentrations and has a longer elimination time, which may produce sustained therapeutic effects. This pharmacokinetic characteristic explains why oral ketamine has a rational role in chronic pain management.

Clinical Evidence: Key Findings from Australian Research

Safety Data in Chronic Pain Management

A retrospective case series from the Royal Prince Alfred Hospital Pain Management Centre provided initial evidence of the long-term safety of oral/sublingual ketamine. The study included 29 patients with chronic non-malignant pain who received sublingual ketamine troches between 2012 and 2019.

Key findings:

• Doses ranged widely, from 25mg to 600mg (divided doses)
• Treatment duration ranged from 2 months to 89 months
• 59% of patients reduced their use of opioids, gabapentinoids, or benzodiazepines, with 39% completely ceasing at least one analgesic
• 24% reported side effects, but only 7% discontinued due to side effects (sedation)
• No renal impairment, cystitis, or hepatotoxicity was reported

An important conclusion from this study was that “safe” doses may be higher than previously consensus suggested.

Breakthrough Findings in PTSD Treatment

An open-label pilot study by the University of the Sunshine Coast (UniSC) National PTSD Research Centre explored the effects of low-dose oral ketamine on PTSD. The study included 22 participants (aged 22-77), including those with lifelong PTSD and comorbid depression.

Key results:

• 73% of participants experienced more than 50% reduction in PTSD symptoms one week after treatment completion
• 59% maintained this improvement at one month
• Participants reported reductions in depression, stress, suicidal ideation, and improvements in sleep quality, social and occupational functioning
• All participants’ side effects resolved before leaving the study, with fewer side effects than intravenous ketamine

Lead researcher Dr Bonnie Quigley noted the advantage of oral ketamine: “Oral ketamine patients can receive treatment in a doctor’s office, whereas intravenous ketamine requires administration under hospital or clinic supervision.”

Legal Status and Regulatory Requirements

Prescription Controls: Schedule 8 Medicine

Ketamine is a Schedule 8 (S8) controlled medicine in Australia, subject to strict prescription regulation. For treatment-resistant depression, only AHPRA-registered psychiatrists can prescribe esketamine or ketamine. In New South Wales, psychiatrists must apply for approval through SafeScript NSW (the real-time prescription monitoring system).

Dispensing Pathway: Compounding Pharmacies

Oral ketamine is typically prepared as troches or lozenges by compounding pharmacies. Australian compounding pharmacies provide pain management solutions including various ketamine formulations such as topical creams, solutions, and troches. These preparations require a prescription, and most high-strength pain medicines are not available over the counter.

A Cautionary Case

A case from the New South Wales Civil and Administrative Tribunal revealed regulatory risks in oral ketamine prescribing. A doctor was alleged to have prescribed 800mg ketamine troches daily to two patients (Patient M and N), with 300 tablets per dispensing. The doctor argued that oral ketamine has a bioavailability of only 29%, so different therapeutic standards applied, and the dose was “within reported ranges.”

However, the literature relied upon by the Tribunal did not support the doctor’s views on the safety and efficacy of long-term ketamine for chronic pain. This case demonstrates that off-label use of oral ketamine exists in a regulatory grey area, and the appropriateness of prescribing may face strict scrutiny.

Comparing Oral Ketamine with Other Administration Routes

Comparison with Esketamine Nasal Spray

Esketamine nasal spray (Spravato) is the only approved ketamine-based product for TRD and has been PBS-listed since May 2025. Its medication cost is $31.60 per dose (or $7.70 for concession card holders), but it must be self-administered at a registered treatment facility under medical supervision.

The advantage of oral ketamine is that it can be used in a doctor’s office or even at home, without the need for specialised clinic facilities. However, its disadvantage is equally clear: there is no PBS subsidy. While the medication cost is low (generic ketamine at approximately $5-20 per dose), the clinical costs of prescribing and monitoring are borne by the patient.

Comparison with Intravenous Ketamine

Intravenous ketamine has 100% bioavailability and rapid onset, but must be administered under hospital or clinic supervision. Oral ketamine, while slower in onset and with lower peak concentrations, offers greater clinical accessibility, particularly for patients requiring daily or intermittent dosing regimens.

Conclusion

Oral ketamine in Australia is an off-label prescription medicine, prepared as troches or lozenges by compounding pharmacies. Australian research shows it demonstrates good safety and efficacy in chronic pain and PTSD treatment, with fewer side effects than intravenous ketamine. However, its legal status is a Schedule 8 controlled medicine, requiring prescription by specialist doctors, and in NSW, approval through SafeScript. For patients seeking treatment, discussing the suitability of oral ketamine with a pain specialist or psychiatrist is the only legal pathway.