The rise of ‘Vitamin K’ (AKA Ketamine) misuse: what GPs need to know about going down the ‘K-hole’

When I think about vitamin K my immediate reaction is ‘important micronutrient and crucial for reversing warfarin’. But this blog is about a very different type of vitamin K, namely ‘Vitamin K’ AKA Ketamine.  Talk to Frank duly informs me it also goes by a variety of other names including ‘K’, ‘special K’ and ‘super K’. My appraisal is due soon, so there is the usual brain-wracking to drag out a few PUNS and DENS…then the February BJGP dropped through my letterbox and I very nearly skipped over the clinical practice review on ‘Ketamine misuse: an update for primary care’ (BJGP 2023; 73 (727): 87-89). Ketamine misuse? Is this really something common that I need to be aware of? Well, it turns out yes, I probably do. A Big DEN.

My teenage son clearly feels I’m very much drifting into the ‘old fart’ stage of life - the eye rolling whenever we try to discuss anything he considers outside my ‘dad’ remit, and liberal use of urban slang that is sometimes indecipherable…’ man, he was really dusty’ (Eh? I’m sorry, what?). But when it comes to the patterns of drug misuse in teenagers and young adults he is probably absolutely right - I really am behind the times, and I feel woefully naive on this subject.

So what are the drugs being used by teenagers and young adults? The latest ONS stats on drug misuse were published in December 2022. COVID and the reduction in opportunities for socialising has inevitably skewed the data somewhat, but it was no surprise that cannabis remains the most common drug used with 16.2% of adults aged 16-24 reporting use in the last year. But the one that stuck out for me was ketamine misuse, which was rising steeply before the pandemic, and levels of use have been maintained since with ~3.2% of 16-24-year-olds having reported use in the past year. This rate is similar (in this age group) to nitrous oxide and powder cocaine use (~4%) and much higher than both amphetamines and ecstasy use (~1%). 

So this data suggests ~1:30 of our 16-24-year-old population will have used ketamine in the last year, and whilst many will only use this infrequently the ONS data suggests >40% of those misusing drugs will do so on at least a monthly basis. All in all, it feels like I need to be a bit more aware of ketamine use and how it may present to us in General Practice, and this BJGP review article gave an excellent summary.

Ketamine has been used in both veterinary and medical practice for many years, and can be useful in acute settings owing to its anaesthetic and sedative properties, with a lower risk of respiratory depression. It started becoming a drug of misuse during the 1990s dance scene, giving powerful dissociative experiences, and is generally snorted giving a relatively quick onset of action in ~15 minutes. It inhibits the NMDA receptor giving a psychosis-like state, and the inhibition of catecholamine uptake gives rise to associated tachycardia and hypertension. Acute effects include anaesthesia, impaired motor function (e.g. ataxia), depersonalisation and hallucinations. High doses produce profound detachment from reality, known as the ‘K-hole’. Other effects include GI disturbance with nausea and vomiting, upper abdo pain (thought due to bile duct dilation) and colicky pain (known as ‘K-cramps’.…you can see a thread with the terminology here). As with all drugs that affect the NMDA receptor ketamine can affect memory and cognition, and can also cause depression. The risks of death from acute toxicity are very low, with most deaths due to reckless behaviour whilst on the drug (especially as it is often taken with other drugs, notably alcohol together with which deaths are reported) and the associated anaesthetic effects meaning injury may not be noticed. 

Somewhat conversely there has been interest in a nasal form of ketamine, Esketamine, as an acute-onset antidepressant. I was somewhat taken aback when I heard about this a few years ago, given the risks of this drug, and it all felt a bit ‘oxycontin-ish’. It was licensed in Europe for treatment-resistant depression in 2019, but ‘grave concerns’ have been raised about the lack of evidence and potential risk profile (BMJ 2019;367:l7069) and NICE have recently recommended against it’s use (TA 894 Dec 2022), although it is available in private clinics. 

So, for those of us less familiar with ketamine, I guess we won’t be surprised at many of those side effects - asking about potential drug misuse in the context of young people with depression, hallucinations or cognitive issues would be standard practice, although maybe we need to be a bit more specific and ask about ketamine. But tachycardia or hypertension or recurrent abdo pains/GI symptoms? I’m not sure I would necessarily think about drug misuse, and certainly not ketamine. And what about recurrent cystitis? That certainly would not cross my radar, however, this is now a well-recognised complication of recurrent ketamine use. It can cause ulcerative cystitis giving rise to bladder pain, lower urinary tract symptoms, non-visible haematuria and sterile pyuria. 

So, lots of useful learning points for me, especially the association with recurrent sterile cystitis. DEN on ‘Vitamin K’ misuse - Done.