A Practitioner’s Guide to Prescribing Ethosuximide for Adults with Intellectual Disabilities

Abstract

We developed this ethosuximide guideline using drug prescribing ­information and reviewing the available literature on relevant neuropsychiatric disorders in populations without intellectual disabilities because of the dearth of available literature on the population with intellectual disabilities. This guideline includes indications; contraindications; assessments prior to and during treatment; dosing with particular focus on dosing modifications required by drug–drug interactions, personal characteristics; and adverse drug reactions. The procedures contained in this guideline may not fully account for all of the possible risks of treatment in this population because of the limited studies available; thus, there will be a need to periodically update this guideline as new information becomes available. Nevertheless, we believe that this guideline provides a useful resource for clinicians who treat epilepsy in adult individuals with intellectual ­disabilities. An ethosuximide drug utilization review that summarizes this guideline is described.

Appendix Drug Utilization Review: Ethosuximide

DRUG UTILIZATION REVIEW CRITERIA				CRITERIA MET ETHOSUXIMIDE FOR ADULTS WITH IDs
				YES	NO	NA
1) Indication: Check one of the following indications for use
‫	Absence epilepsy (petit mal).
‫	Other: Specify_________________________. When ethosuximide is used for off-label indications, the chart specifically includes an explanatory note (Y___ N___).
To meet indication criteria, at least one indication is present and documented.				‫	‫
2) Dose:_____
	The initial antiepileptic dose was ≤ 500 mg/day (Y__, N___) unless recommended otherwise by a consultant with expertise in the area (Y__).			‫	‫	‫
	The maximum antiepileptic dosage was ≤ 1,500 mg/day (Y__, N___) unless recommended otherwise by a consultant with expertise in the area (Y__).			‫	‫	‫
	Taking phenytoin__, carbamazepine__, phenobarbital__, or primidone__. The chart documents the interaction (Y___ N___). The dosage of ethosuximide may need to be increased when an inducer is added and the discontinuation of the inducer may need to be followed by a decrease in ethosuximide dosage.			‫	‫	‫
	Taking other inducers___________________________. The chart documents the interaction (Y___ N___). The dosage of ethosuximide may need to be increased when an inducer is added and the discontinuation of the inducer may need to be followed by a decrease in ethosuximide dosage.			‫	‫	‫
	Taking potent CYP3A inhibitors: For example, ketoconazole__, itraconazole__, fluconazole___, erythromycin___, fluoxetine___, fluvoxamine___, clarithromycin___, diltiazem___, or other________ or isoniazid__. The chart documents the interaction (Y___ N___). The ethosuximide dosage may need to be decreased when an inhibitor is added and the discontinuation of the inhibitor may need to be followed by an increase in ethosuximide dosage.			‫	‫	‫
To meet dose criteria, all are Yes or NA.				‫	‫
3) Relative contraindications: Check any present.
‫	Pregnancy or breast feeding.
‫	Hepatic or renal impairment.
If any of the above are checked, the rationale is documented in the chart to meet relative contraindication criteria. If none are present, check NA.				‫	‫	‫
4) Baseline monitoring studies:
‫	CBC.
‫	Liver function tests.
‫	Serum creatinine and BUN.
‫	Serum concentrations of concomitantly administered antiepileptics, which are usually followed with therapeutic drug monitoring.
Answer Yes or No. If information is not applicable, check NA.				‫	‫	‫
5) Monthly monitoring studies:
‫	Ethosuximide levels are monitored at least every month for 3 months, and then every 6 months thereafter.
Answer Yes or No. If information is not applicable, check NA.				‫	‫	‫
6) Semiannual monitoring studies:
‫	Ethosuximide levels.
Answer Yes or No. If information is not applicable, check NA.				‫	‫	‫
7) Discontinuation:
	Ethosuximide is or was withdrawn slowly to minimize the potential of increased seizure frequency. Abrupt withdrawal was justified by a major medical reason.			‫	‫	‫
8) Adverse drug reactions (ADRs) due to ethosuximide: Check left boxes to indicate which ADRs are present.
8.1) Common ADRs:
‫	CNS symptoms: Drowsiness, lethargy, euphoria, dizziness, headache, or hiccup.	‫	Gastrointestinal: Nausea, vomiting, or anorexia.
8.2) Relatively uncommon ADRs:
‫	Psychiatric symptoms: Restlessness, agitation, anxiety, aggressiveness, inability to concentrate, or psychotic behavior.	‫	Parkinson-like symptoms or photophobia.
‫	Systemic lupus erythematosus or pseudolymphomas.	‫	Transitory leukopenia.
‫	Other_____________	‫	Other_____________
8.3) Potentially lethal ADRs:
‫	Stevens–Johnson syndrome/toxic epidermal necrolysis or hypersensitivity syndrome.	‫	Agranulocytosis or aplastic anemia.
‫	Suicidal ideation or behavior.
Answer Yes (intervention or benefit/risk discussion after ADRs developed) or No (neither intervention nor benefit/risk discussion after ADRs developed) or NA (no abnormality developed).				‫	‫	‫