Pharmacist Impact on Posttraumatic Seizure Prophylaxis
Pharmacist Impact on Posttraumatic Seizure Prophylaxis
Phenytoin is the most commonly administered antiepileptic agent for the prevention of early (<= 7 days) posttraumatic seizures. Use of the agent, however, requires strict monitoring due to its narrow target range and nonlinear pharmacokinetics. The impact of a clinical pharmacist participating in the care of patients with head injury on posttraumatic seizure prophylaxis with regard to phenytoin dosing and monitoring, cost avoidance, and patient outcome, was measured retrospectively. Parameters from time periods before (BP) and after (AP) a clinical pharmacist participated in patient care were compared. The average number of days that phenytoin was given was 13.4 (BP) and 7.6 (AP), and the duration of phenytoin prophylaxis was 7 days or less in 35% and 65% of patients, respectively. The average number of phenytoin levels drawn from each patient was 10.3 (BP) and 3.4 (AP). Seizures occurred in 4.7% (BP) and 1.5% (AP) of patients. A cost savings of approximately $28,000 was observed for the AP group. A clinical pharmacist reduced the use of posttraumatic seizure prophylaxis and associated costs without jeopardizing patient outcomes.
Phenytoin is one of the most commonly administered antiepileptic agents given to patients in the neuroscience intensive care unit because of its availability in both parenteral (phenytoin and fosphenytoin) and oral-enteral formulations. A full understanding of its pharmacokinetic characteristics is necessary to optimize its therapeutic effects while avoiding adverse effects and excess costs to the patient and institution. Phenytoin has a narrow target range (10-20 µg/ml total phenytoin concentration, 1-2 µg/ml unbound phenytoin concentration), and its concentration is affected by altered protein binding and metabolic changes associated with head injury. Vigilant clinical and laboratory monitoring of phenytoin is required because of the agent's significant acute and chronic side effects and because seizure occurrence after head injury may increase morbidity.
Seven days of phenytoin or carbamazepine is recommended for posttraumatic seizure prophylaxis in high-risk patients with head injury. Patients are considered high risk if they have a Glasgow Coma Scale (GCS) score of less than 10, cortical contusion, depressed skull fracture, subdural hematoma, epidural hematoma, intracerebral hematoma, penetrating head wound, and/or seizure within 24 hours of injury. Due to the physical state of such patients, seizures and signs and symptoms of toxicity are difficult to detect. Therefore, maintaining target trough phenytoin concentrations is the most common goal for monitoring posttraumatic seizure prophylaxis.
Posttraumatic seizure prophylaxis with phenytoin is the standard of care for patients with head injury at the neuroscience intensive care unit at our medical center. In October 1996, a clinical pharmacist joined the health care team. Before the pharmacist's involvement, patients with head injury received phenytoin for posttraumatic seizure prophylaxis for 3 days to more than 30 days. Loading doses of phenytoin were not based on patient weight, and mini-loading doses were given with or without adjustments in maintenance dosages. Phenytoin levels were drawn without regard to time of the last dose, severe hypoalbuminemic states were not considered when calculating appropriate dosages, and free phenytoin levels were seldom drawn. In addition, before the participation of the clinical pharmacist, patients were seldom switched from intravenous to oral phenytoin during their intensive care unit stays. These observations, which were made by the clinical pharmacist, resulted in pharmacy-conducted education sessions for physicians and nurses as well as suggested guidelines, consistent with published recommendations, for phenytoin dosing, monitoring, and duration of therapy for posttraumatic seizure prophylaxis.
In today's team-based approach to patient care, clinical pharmacists make a significant contribution to the multidisciplinary health care team. This study evaluated the impact of a clinical pharmacist's involvement on post-traumatic seizure prophylaxis in patients with head injury, with regard to phenytoin dosing and monitoring, cost avoidance, and patient outcome.
Phenytoin is the most commonly administered antiepileptic agent for the prevention of early (<= 7 days) posttraumatic seizures. Use of the agent, however, requires strict monitoring due to its narrow target range and nonlinear pharmacokinetics. The impact of a clinical pharmacist participating in the care of patients with head injury on posttraumatic seizure prophylaxis with regard to phenytoin dosing and monitoring, cost avoidance, and patient outcome, was measured retrospectively. Parameters from time periods before (BP) and after (AP) a clinical pharmacist participated in patient care were compared. The average number of days that phenytoin was given was 13.4 (BP) and 7.6 (AP), and the duration of phenytoin prophylaxis was 7 days or less in 35% and 65% of patients, respectively. The average number of phenytoin levels drawn from each patient was 10.3 (BP) and 3.4 (AP). Seizures occurred in 4.7% (BP) and 1.5% (AP) of patients. A cost savings of approximately $28,000 was observed for the AP group. A clinical pharmacist reduced the use of posttraumatic seizure prophylaxis and associated costs without jeopardizing patient outcomes.
Phenytoin is one of the most commonly administered antiepileptic agents given to patients in the neuroscience intensive care unit because of its availability in both parenteral (phenytoin and fosphenytoin) and oral-enteral formulations. A full understanding of its pharmacokinetic characteristics is necessary to optimize its therapeutic effects while avoiding adverse effects and excess costs to the patient and institution. Phenytoin has a narrow target range (10-20 µg/ml total phenytoin concentration, 1-2 µg/ml unbound phenytoin concentration), and its concentration is affected by altered protein binding and metabolic changes associated with head injury. Vigilant clinical and laboratory monitoring of phenytoin is required because of the agent's significant acute and chronic side effects and because seizure occurrence after head injury may increase morbidity.
Seven days of phenytoin or carbamazepine is recommended for posttraumatic seizure prophylaxis in high-risk patients with head injury. Patients are considered high risk if they have a Glasgow Coma Scale (GCS) score of less than 10, cortical contusion, depressed skull fracture, subdural hematoma, epidural hematoma, intracerebral hematoma, penetrating head wound, and/or seizure within 24 hours of injury. Due to the physical state of such patients, seizures and signs and symptoms of toxicity are difficult to detect. Therefore, maintaining target trough phenytoin concentrations is the most common goal for monitoring posttraumatic seizure prophylaxis.
Posttraumatic seizure prophylaxis with phenytoin is the standard of care for patients with head injury at the neuroscience intensive care unit at our medical center. In October 1996, a clinical pharmacist joined the health care team. Before the pharmacist's involvement, patients with head injury received phenytoin for posttraumatic seizure prophylaxis for 3 days to more than 30 days. Loading doses of phenytoin were not based on patient weight, and mini-loading doses were given with or without adjustments in maintenance dosages. Phenytoin levels were drawn without regard to time of the last dose, severe hypoalbuminemic states were not considered when calculating appropriate dosages, and free phenytoin levels were seldom drawn. In addition, before the participation of the clinical pharmacist, patients were seldom switched from intravenous to oral phenytoin during their intensive care unit stays. These observations, which were made by the clinical pharmacist, resulted in pharmacy-conducted education sessions for physicians and nurses as well as suggested guidelines, consistent with published recommendations, for phenytoin dosing, monitoring, and duration of therapy for posttraumatic seizure prophylaxis.
In today's team-based approach to patient care, clinical pharmacists make a significant contribution to the multidisciplinary health care team. This study evaluated the impact of a clinical pharmacist's involvement on post-traumatic seizure prophylaxis in patients with head injury, with regard to phenytoin dosing and monitoring, cost avoidance, and patient outcome.
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