Ketamine hydrochloride is a safe and rapid-acting non-opioid, lipid soluble anaesthetic with a short elimination halflife that is used for medical and veterinary purposes. It produces a state of "dissociative anaesthesia", probably from action on N-methyl-D-aspartate (NMDA) receptors. The psychotropic effects of ketamine range from dissociation and depersonalization to psychotic experiences and include a sensation of feeling light, body distortion, absence of time sense, novel experiences of cosmic oneness and out-of-body experiences. Abuse of ketamine has been reported, the typical abuser being an individual who uses multiple drugs and has some contact with medical agencies. This case demonstrates the effects of large doses of ketamine in a person with polysubstance abuse. The case also highlights development of significant tolerance to ketamine without prominent withdrawal symptoms. Caution in use of ketamine is reiterated in light of its abuse liability.

Objective: To study unusual psychiatric manifestation of vitamin B12 deficiency and related issues.Method: A case study of 52‐year‐old female and review of relevant literature.Results: Complete remission of psychiatric symptoms without recurrence for the next 4 years with vitamin B12 as the only specific therapy instituted.Conclusion: Importance of B12 estimation and replacement in patients with varied psychiatric manifestations.

A 16-year-old boy developed fever, generalized rigidity, leukocytosis, and increased serum transaminase and creatine kinase levels while receiving treatment with olanzapine and lithium. When both drugs were discontinued, his fever and rigidity subsided and biochemical irregularities spontaneously returned to normal, without any complications. Classic neuroleptic malignant syndrome (NMS) was diagnosed. Concomitant administration of lithium with olanzapine may place patients at risk for NMS. Clinicians need to be aware of this rare but potentially fatal side effect in patients of all ages, and especially in adolescents receiving both drugs.

The abuse of cough syrups containing antihistamines and codeine is being increasingly noted. The abuse of antihistamines alone has also been reported. The use of antihistamines alone or in combination with other substances of abuse may predispose individuals to develop psychiatric symptoms or syndromes as a part of intoxication, withdrawal or as co-morbid conditions. We present two case reports to highlight the occurrence of co-morbid psychopathology in association with antihistamine abuse and dependence.Case I used high doses of pheniramine for about 2 years and became suspicious of his wife; he even doubted the paternity of his yet-to-be-born child. The associated behavioural abnormalities suggested that he was acting out on the delusion. He also had seizures associated with the intake of a high dose of pheniramine. Case II had multiple substance use, and dependence on alcohol and pheniramine. He demonstrated abnormal behaviour suggestive of psychosis and organic brain syndrome that persisted for a few days and remitted on discontinuation of the substances. These two cases demonstrate the occurrence of psychotic syndromes associated with heavy pheniramine use. The psychopathology can vary from an independent psychotic syndrome to an organic brain syndrome-like disorder.

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