A 31-year-old male educated up to 10th standard, shopkeeper by profession, belonging to middle socio-economic strata in an urban area with no prior psychiatric history was brought by his wife to the psychiatry outpatient department with the complaints of incoherent speech, garbled sentences, paranoid ideation regarding his family (plotting against him and conspiring to steal his belongings), listening to voices (auditory hallucinations), and shouting at people who were not around since the last 2 days. These symptoms were associated with intermittent insomnia and a desire to stay in isolation and darkness.
The symptoms started about 4 weeks after he was put on INH 300 mg/day, rifampicin 600 mg/day, ethambutol 800 mg/day, and pyrazinamide 1,500 mg/day for pulmonary TB and pyridoxine (vitamin B6) 20 mg/day for prophylaxis against neuropathy by the prescribing physician. There was no history of recent ingestion of any psychoactive substances. His brother had a distant history of social anxiety disorder/social phobia, and his sister had a positive past history of bulimia nervosa in her teenage years that resolved after 4 months of treatment.
The physical examination was unremarkable, and the vital signs were stable, and testing including a complete blood count, chest X-ray, and urine toxicology screening were all within the normal ranges. A thyroid function test initially showed a marginally low thyroid-stimulating hormone with normal triiodothyronine and thyroxine. A computed tomography scan of the head showed no abnormality. Due to the absence of any other eminent cause of this behavior change, an initial diagnosis of drug-induced psychosis due to INH was contemplated.
Thereafter, all the antitubercular therapy was stopped by the prescribing physician. Although he responded minimally after INH was stopped, the auditory hallucinations, shouting, and the paranoid ideation still persisted. Subsequently, the patient was put on tablet olanzapine 10 mg/day and tablet lorazepam 2 mg/day by the treating psychiatrist. Rifampicin, pyrazinamide, and ethambutol were successively reintroduced, to monitor a possible relapse of symptoms. INH was not reintroduced as it was the most likely offending drug taken into consideration for the symptoms and was subsequently replaced with tablet levofloxacin 750 mg/day by the treating physician to complete the antitubercular treatment regimen as per the standard treatment guidelines. Eventually, the patient became asymptomatic after taking olanzapine for a period of 15 days.
The patient did not require olanzapine and lorazepam 7 weeks after his visit to the treating physician and also agreed for follow-ups. He remained asymptomatic at the subsequent follow-up visits to the hospital.
The Brief Psychiatric Rating Scale (BPRS) is a commonly employed scale that is used to establish the possible presence and severity of various psychiatric disorders. The BPRS score was evaluated to be 47 in this patient as per the treating psychiatrist on the 5th day, thereby determining the severity as moderate.
The causality assessment of the adverse drug reaction came out to be possible for this case using the Naranjo Causality Assessment Scale. The case was reported to the adverse drug reaction monitoring center under the Pharmacovigilance Programme of India (PvPI).