McKenna's Pharmacology for Nursing, 2e

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P A R T 4  Drugs acting on the central and peripheral nervous systems

Drug therapy across the lifespan

BOX 23.2

Antiseizure agents CHILDREN

seizures as well as the lifestyle changes and drug effects that they may need to cope with. PREGNANCY AND BREASTFEEDING Most of these drugs have been associated with fetal abnormalities in animal studies. Some of them are clearly associated with predictable congenital effects in humans. Women of childbearing age should be encouraged to use contraceptives while taking these drugs. If a pregnancy does occur, or if a woman taking one of these drugs desires to become pregnant, the importance of the drug to the mother should be weighed against the potential risk to the fetus. Stopping an antiepileptic can precipitate seizures that could cause anoxia and its related problems for the mother and the baby. Women who are breastfeeding should be encouraged to find another way of feeding the baby to avoid the sedating and central nervous system (CNS) effects that the drugs can have on the infant. OLDER ADULTS Older people may be more susceptible to the adverse effects of these drugs. Dosages of all of these drugs may need to be reduced, and the person should be monitored very closely for toxic effects and to provide safety measures if CNS effects do occur. People with renal or hepatic impairment should be monitored very closely. Baseline renal and liver function tests should be done and dosages adjusted as appropriate. Serum levels of the drug should be monitored closely in such cases to prevent serious adverse effects. The older person should also be encouraged to wear or carry Medic-Alert identification in case there is an emergency and they are not able to communicate information about the drug or disorder.

Antiepileptic drugs can have an impact on a child’s learning and social development. Children may also be more sensitive to the sedating effects of some of these drugs. Children should be monitored very closely and often require a switch to a different agent or dosage adjustments based on their response. Newborns (1 to 10 days of age) respond best to intramuscular phenobarbitone if an antiepileptic is needed. Older children (2 months to 6 years of age) absorb and metabolise many of these drugs more quickly than adults do and require a larger dosage per kilogram to maintain therapeutic levels. Careful calculation of drug dosage using both weight and age are important in helping the child to receive the best therapeutic effect with the least toxicity. After the age of 10 to 14 years, many of these drugs can be given in the standard adult dose. Parents of children receiving these drugs should receive consistent support and education about the seizure disorder and the medications being used to treat it. Many communities have local support groups that can offer lots of educational materials and support programs. It is a very frightening experience to watch your child have a tonic– clonic seizure and parents should be supported with this Adults using these drugs should be under regular care and should be monitored routinely for adverse effects. They should be encouraged to carry or wear a Medic- Alert identification to alert emergency personnel that antiepileptic drugs are being taken. Adults also need education and support to deal with the old stigma of in mind. ADULTS

■■ TABLE 23.1 Antiepileptic drug therapy grouped by seizure class

Cultural considerations

BOX 23.3

Altered metabolism of antiseizure agents Because of differences in liver enzyme functioning among Arabs and Asians, people in these ethnic groups may not metabolise antiseizure agents in the same way as people in other ethnic groups.They may require not only lower doses to achieve the same therapeutic effects, but also frequent dose adjustment. Nurses and midwives need to be aware that the therapeutic range for people in these ethnic groups may differ from standard norms and that these people may be more apt to show adverse or toxic reactions to antiepileptic drugs at lower doses. As with all medications, the lowest possible dose should be used. Serum drug levels should be closely monitored and titrated carefully and slowly to achieve the maximum benefits with the fewest adverse effects.

Generalised seizures (except status epilepticus)

Seizures

Status epilepticus

Carbamazepine Carbamazepine Diazepam Clonazepam Clonazepam Lorazepam Gabapentin Ethosuximide Midazolam Lacosamide Lamotrigine Phenobarbitone Lamotrigine Levetiracetam Phenytoin Levetiracetam Oxcarbazepine Propofol Oxcarbazepine Phenytoin Phenytoin Sodium valproate Pregabalin Topiramate Sodium valproate Vigabatrin Tiagabine Zonisamide

Topiramate Zonisamide

Adpted from Aschenbrenner, D. S. &Venable, S. J. (2008). DrugTherapy in Nursing (3rd edn). Philadelphia: Lippincott Williams &Wilkins, p. 331.