Does opioid and ketamine “codependence” exist?

Dear Sir, There are several case reports of ketamine dependence in the literature. Furthermore, recent research has shown the therapeutic use of ketamine beyond anesthesia in opioid-dependent patients for reducing perioperative pain [1] and to reduce opioid withdrawal symptoms.[2] A recent case report demonstrated successful use of opioid receptor antagonist naltrexone for ketamine dependence.[3] Taken together, these intuitively raise the possibility of pharmacodynamic proximity between opioid and ketamine beyond common risk factors. We here present a case of opioid and ketamine codependence in a health worker. Moreover, we raise the possibility that ketamine dependence might be in part determined by past opioid dependence in particular. A 36-year-old married male hailing from rural Jharkhand, India, working as an operation theater (OT) attendant in a private hospital presented with complaints of using ketamine injections for 3 years and low mood, decreased interest in work, and interaction for 6 months. His history revealed regular use of injection pentazocine for 2 years before he started using ketamine injections regularly. He met a road traffic accident 5 years back and underwent a surgical procedure for the fracture of right lower limb bones. After surgery, he was prescribed injection pentazocine for pain for some days. However, after it was stopped under the supervision of treating doctor, he started feeling uneasiness and low mood. Due to easy availability of injection pentazocine in OT, he continued taking it on his own, which gradually kept on increasing in frequency and within 3 months he started taking it on everyday pattern. He continued taking it only 1 ampoule per day. He was taking this injection intravenously in upper limbs. As he was taking only 1 ampoule per day, he could continue taking it without others' noticing it. Gradually, his veins of upper limb started getting fibrosed and 1 day this came to the notice of other OT personnel. He decided to completely stop it, but failed every time as he used to feel low mood and poor interest in work on cessation of use of injection. Meanwhile, he came to know about ketamine which happened to be commonly used during surgical procedures in OT where he used to work. Gradually, he started taking intramuscular ketamine injections in upper limbs, instead of injection pentazocine. He would take around 1.0–1.5 ml (50 mg/ml) and the maximum reported dose was 2.0 ml. After taking ketamine injections, he used to feel better and regain his interest in work. In addition, he used to feel that he was flying in the air and every object became clearer. His concentration powers and interest in work increased. These effects were short lasting for 5–10 min, but he used to feel difficulty in recollecting events that would have occurred during that period. Neither his present illness nor history revealed the use of any other psychoactive substance including tobacco and caffeine. He kept taking ketamine on a regular basis till he was persuaded to consult at our deaddiction center. He was admitted in deaddiction center of our institute and considering his prior history of opioid dependence, tablet naltrexone (50 mg/day) was started after detoxification. Motivational enhancement therapy was done. After discussion with the patient and their family members, naltrexone was chosen for long-term treatment. There was a significant reduction in craving on visual analog scale and improvement in physical and psychological symptoms within 2 weeks. Relapse prevention session was taken regularly during ward stay. Our case displays ketamine and opioid “codependence” in a health worker. Chemically, ketamine is an ary-cyclohexylamine compound, a close relative of phencyclidine and it produces psychotropic effects when used in a dose range from 25 to 200 mg. It acts principally on the N-methyl-D-aspartate subtype of the glutamate receptor.[4] In addition, ketamine has opioidergic effects (mu- and sigma-opiate agonism) contributing to its analgesic properties and stimulant-like properties by enhancing monoaminergic transmission (dopamine, norepinephrine, and serotonin) through inhibition of reuptake pumps.[5] This case raises the possibility of opioid and ketamine “codependence” and illustrates that patients of opioid dependence are vulnerable to subsequent ketamine dependence. This vulnerability may persist even after cessation of opioids. Considering easy access to these substances, healthcare workers are the most vulnerable for ketamine dependence. More research is required to look into this association. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Abstract licence: CC BY-NC-SA

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