Azithromycin/benzonatate/methocarbamol

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An event is serious (based on the ICH definition) when the patient outcome is:

• * death

• * life-threatening

• * hospitalisation

• * disability

• * congenital anomaly

• * other medically important event

A 43-year-old man developed catatonia following treatment with azithromycin, benzonatate and methocarbamol. He additionally developed confusion and auditory hallucinations following treatment with benzonatate, and it was suspected that he might have taken more methocarbamol than what he was prescribed in his state of confusion [not all routes and dosages stated; durations of treatments to reactions onsets not clearly stated].

The man presented to hospital with headache and fever. COVID-19 was suspected; however, since he did not meet criteria for testing, he was discharged with a recommendation for home quarantine. After 9 days, he re-presented with fever and shortness of breath. Therefore, COVID-19 nasopharyngeal swab PCR was performed, and he was discharged with a prescription for oral azithromycin for 5 days: 500mg on day 1, followed by 250mg on days 2−5, benzonatate as required for cough and salbutamol [albuterol]. However, after 3 days, he presented with complaints of upper back pain and spasms. He also reported anxiety and insomnia due to his concerns of COVID-19. He was informed about his previous COVID-19 PCR being negative. He stated that he had been compliant with the azithromycin; he was encouraged to complete the course. His back pain was believed to be musculoskeletal, resulting from persistent coughing. He was discharged with a prescription for methocarbamol 750mg, four times a day for 7 days. However, after 4 days, (i.e. 2 days after completing his course of azithromycin) his wife informed his physician that she was concerned about her husband acting strangely since the test for COVID-19. He had been talking to himself, not showering and not eating or drinking properly. He would frequently stare at the wall, and he was sweating and shaking without a fever. Therefore, he was hospitalised for work-up and treatment of his altered mental status. Repeat COVID-19 PCR was found positive. The psychiatry team was consulted on hospital day 2, at which time, he was observed to be alert and oriented to person, time and place. However, he exhibited delayed verbal responses, difficulty resisting gravity in all limbs, profound muscle rigidity and profuse diaphoresis. He was extremely weak. The subsequent morning (hospital day 3), his nurse found him resting in an abnormal position, with his arms in a decorticate position and his feet hovering above the bed, in a state of catatonia.

The man was administered lorazepam in preparation for further diagnostic tests. Thirty minutes later, was sitting up and conversing with his roommate. His sweating subsided. He asked for something to drink and informed his nurse that he had been hearing voices. He continued receiving lorazepam, and by hospital day 5, his condition stabilised. He exhibited no further signs of catatonia. He remained nonrigid and conversant, eating and drinking adequately. Lorazepam was gradually tapered by the day of discharge (hospital day 10), by which time, he was speaking fluently and moving all extremities without difficulty. Psychosis was not evidenced. On psychiatric evaluation 4 days post discharge, he reported no difficulty with movement or speech, and no psychosis; however, he reported experiencing difficulty sleeping. The dose of lorazepam was decreased further. On evaluation 6 days post discharge, he continued to experience sleep disturbance, as well as anhedonia and sadness. His wife stated that his condition improved, but his mood did not recover completely, as he needed encouragement to engage in conversation and his occupation. After further psychiatric follow-up, he continued receiving lorazepam for residual psychomotor retardation, and melatonin for insomnia. The brief phase of psychosis was attributed to COVID-19-related anxiety, and it was also believed to have contributed to the development of catatonia. The auditory hallucinations and confusion were attributed to benzonatate, and it was believed that he might have taken more methocarbamol than what he was prescribed in his state of confusion. The development of catatonia was attributed to azithromycin, with benzonatate and methocarbamol being contributing factors.