Unusual idiosyncratic reactions to carbamazepine

Causality, Severity, and Avoidability of Adverse Drug Reactions in Hospitalized Children: A Prospective Cohort Study

BACKGROUND

 Adverse drug reactions are an important cause of morbidity and mortality in all patients. Information regarding adverse drug reactions in the pediatric age group, especially with regard to the drugs involved and the clinical presentations is scanty. The aim of our study is to determine the incidence of adverse drug reactions and to study their features in terms of causality, type, severity, avoidability, drugs implicated and their clinical presentations.

METHODS

 The study was carried out on patients admitted to the pediatric ward and the pediatric intensive care unit over a one-year period (January 1, 2013 to December 31, 2013). Patients either presenting with or developing an adverse drug reaction in the hospital were included in the study.

RESULTS

 The incidence rate for adverse drug reaction causing hospital admission was 1.79% (95% CI 1.48, 2.16) whereas it was 1.23% (95% CI 0.97, 1.53) for children exposed to a drug during their hospital stay. Type B (bizarre or idiosyncratic type) was seen in 114 (62.6%) of the ADRs whereas 53 (29.1%) were of type A (augmented pharmacologic effect). Severe ADRs were seen in 25 (13.7%) of the total ADRs. ADR was responsible for the death of two patients. 15.4% were rated as avoidable. Anti-microbials were the most common group responsible for ADRs (43.4%), followed by drugs acting on the immune system (15.9%) and drugs acting on the nervous system (14.3%). The most common ADRs were metabolic (29.3%) followed by neurological (17.6%).

CONCLUSIONS

 Adverse drug reactions can occur in a substantial proportion of hospitalized patients with some of them being severe and potentially avoidable. Awareness among physicians should be encouraged regarding monitoring, documentation and notification of adverse drug reactions.

Drug-induced movement disorders

Parkinsonism, tremor, chorea-ballismus, dystonia, tardive dyskinesia, myoclonus, tics and akathisia can be induced by many drugs. The drugs that are most frequently implicated in movement disorders are antipsychotics, calcium antagonists, orthopramides and substituted benzamides (e.g. metoclopramide, sulpiride, clebopride, domperidone), CNS stimulants, antidepressants, anticonvulsants, antiparkinsonian drugs and lithium. It is possible for a single drug to induce 2 or more types of movement disorders in the same patient. Movement disorders are not always reversible after drug withdrawal.

Carbamazepine-induced tics

A variety of movement disorders are known to occur in association with carbamazepine (CBZ) therapy in adults and children, but development of tics has been described infrequently and only in patients with underlying Tourette's syndrome or other movement disorders. We report 3 children with epilepsy who developed facial motor tics after initiation of CBZ for complex partial seizures. All 3 had documented CBZ blood levels in the therapeutic range at the time, and none had other symptoms or signs of clinical intoxication. Neurologic examinations were normal in 2 and showed developmental delay of expressive language in the third. Brain imaging was normal in all. After development of the tics in 2, CBZ was continued at the same or higher dose, and the tics abated and then ceased spontaneously < or = 6 months. In the third child, the tics ceased after CBZ discontinuation. These cases demonstrate that CBZ can induce simple motor tics in children. These idiosyncratic reactions may be transient and do not always necessitate drug discontinuation.