Baclofen :: Multiple pharmacies comparison.

Baclofen, a derivative of [gamma]-aminobutyric acid, is used for symptomatic relief of skeletal muscle spasm and spasticity, particularly in patients with multiple sclerosis. (1) Although its exact mechanism is not fully understood, its main effects at the spinal end of upper motor neurons are thought to cause muscle relaxation. Adverse effects of baclofen at usual doses include drowsiness, headache, dizziness, and, occasionally, orthostatic hypotension. (2) Intentional or accidental overdose of this drug can cause profound central nervous system depression, including coma, hypotonia, respiratory depression, seizures, and cardiovascular effects such as bradycardia. Because baclofen is a commonly used antispasticity agent and its use as a recreational drug has been reported, (3) clinicians should be ever vigilant for patients who may have overdosed on this medication. We report a case of surreptitious baclofen intoxication in a patient with seizures and coma.

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Case Report
A 48-year-old, 80-kg man was transferred from a community hospital and admitted to the general intensive care unit of a referral tertiary care teaching hospital after members of his family found him at home unresponsive and having a grand mal seizure. The patient had no history of seizure disorder and had been seen awake and responsive approximately 2 to 2 1/2 hours before the seizure. When found, he was apneic and incontinent of both bladder and bowel. He reportedly had vomited. Emergency responders intubated him at his home.
Initial testing upon arrival at the community hospital included a basic metabolic panel (including serum electrolytes and creatinine), complete blood cell count, and liver function tests (including transaminases, albumin, bilirubin, and serum ammonia); all results were within the reference range. Computed tomography of the head showed no evidence of hemorrhage or other abnormality. A urine toxicology screen was positive for tetrahydrocannabinol and benzodiazepines (however, emergency medical personnel had administered diazepam because of continuing seizure activity) and negative for amphetamines, cocaine, barbiturates, and opioids. Blood alcohol level was zero. Vital signs upon admission were within the reference range except for blood pressures, which ranged from 174 to 207 mm Hg systolic and 99 to 119 mm Hg diastolic. These values decreased over the next several hours to normal without treatment.
The patient’s medical history was significant for a previous back injury for which he had taken pain medications long-term, specifically morphine in the past year, but he had reportedly stopped taking this drug about 1 month before the admission. He was not taking any other known medications at the time of hospitalization. He also had a history of alcohol abuse (he reportedly had quit drinking 8 years earlier). He received no treatment for suspected drug overdose at the outlying hospital.
Upon transfer to the intensive care unit at the referral hospital, approximately 8 hours after the onset of the seizure, the patient was nonresponsive to verbal stimuli and manifested a decerebrate posture upon deep pain stimuli. Vital signs were normal, including blood pressure 130/70 mm Hg, heart rate 75/min, and temperature 37.2[degrees]C. His pupils were 3 mm in diameter and unresponsive to light. Pulses were 1/4 bilaterally with coolness in the lower extremities. The Babinski sign was negative, and the rest of a physical examination revealed no other abnormalities. The patient had no clonus. The results of repeat laboratory studies in the intensive care unit were within the reference range, including normal serum levels of sodium, creatinine, and thyroid-stimulating hormone. Results of the initial arterial blood gas analysis of samples obtained while the patient was receiving intermittent mechanical ventilation (fraction of inspired oxygen 0.60, positive end-expiratory pressure 5 cm [H.sub.2]0, respirations 12/min) were pH 7.40, [Pco.sub.2] 38 mm Hg, [Po.sub.2] 180 mm Hg, bicarbonate 23.3 mmol/L, and oxygen saturation 94%. All other laboratory values were within the reference range. Electroencephalography showed a burst-suppression pattern. The results of a computed tomography angiogram of the head and a lumbar puncture did not indicate any abnormalities.
At this point, detailed questioning of the patient’s family members and investigation of his medical records were undertaken to determine if he had access to or was exposed to any toxic substance. These inquiries revealed that in the past year he had been prescribed the muscle relaxant baclofen. On the basis of this new information, approximately 12 hours after admission to the intensive care unit and 16 hours after the onset of the seizure, a serum sample was sent to a reference laboratory for determination of the baclofen level. No specific treatment for baclofen overdose, including use of activated charcoal, was initiated.
About 24 hours later, movement of the patient’s extremities (left greater than right) was noted; the movement was determined to be nonpurposeful. Forty-eight hours later, the patient had a dramatic improvement in consciousness. He became alert and awake with his eyes opened. He was able to follow commands and was extubated about 12 hours later. Upon questioning, he revealed that he had attempted suicide by taking an entire bottle (unknown total quantity) of baclofen. He was eventually transferred to the inpatient psychiatric ward for treatment of major depression. The results of the serum assay for baclofen, which was received about 1 week after the patient’s transfer to the psychiatric unit, was 1.2 [micro]g/mL (reference serum level for treatment of spasticity is 0.08-0.4 [micro]g/mL). (2)