A Case Report of Accidental Intoxication following Ingestion of Foxglove Confused with Borage: High Digoxinemia without Major Complications

Abstract

Foxglove (Digitalis purpurea L.) leaves are frequently confused with borage (Borago officinalis L.), which is traditionally used as a food ingredient. Due to the presence of the cardiac glycosides, mostly digitoxin, foxglove leaves are poisonous to human and may be fatal if ingested. A 55-year-old Caucasian woman complaining weakness, fatigue, nausea, and vomiting was admitted to the Emergency Department. Her symptoms started following consumption of a home-made savory pie with 5 leaves from a plant bought in a garden nursery as borage. Digoxinemia was high (10.4 μg/L). The patient was admitted to the cardiac intensive care unit for electrocardiographic monitoring. Two days after admission, a single episode of advanced atrioventricular (AV) block was recorded by telemetry, followed by a second-degree AV block episode. Plasma samples at day 11 were analysed by LC-MS spectrometry, and gitoxin was identified suggesting that this compound may be responsible for the clinical toxicity rather than digoxin. In the case of Digitalis spp. poisoning, laboratory data should be interpreted according to the clinical picture and method of analysis used since a variety of glycosides, which are chemically similar to the cardioactive glycosides but without or with fewer cardiac effects, may be incorrectly recognized as digoxin by the test, giving misleading results.

Figure 1

(a) Two fresh leaves belonging to a plant responsible for the intoxication. Samples were deposited at the Poison Centre of Niguarda Hospital, Milan, Italy. The leaves were subjected to macro and microscopic analyses suitable for the identification by a botanist. Then, the leaves were dried and used for phytochemical analyses. (b) Plant during flowering.

Figure 2

(a) Telemetry recordings showing sinus rhythm with a single episode of advanced AV block (two consecutive P waves not followed by a QRS complex—arrows) followed by second-degree AV block episode. Note diffuse ST segment depression with down-up sloping typical of digitalis intoxication. (b) Telemetry recordings showing bigeminal ventricular ectopic beats and a run of accelerated idioventricular rhythm (8 beats at 72 bpm). Reduction of the intoxication signs.

Figure 3

Graphical representation of potassium and digoxin serum levels measured in the study patient from day 0 up to day 12.

Figure 4

Plasma analysis by LC-MS. (a) Plasma profile with peak (A) corresponding to a glycoside unidentified; (b) authentic standard of gitoxin, which allowed to identify the compound in plasma sample; (c) fragmentation of gitoxin with typical fragment at 743 m/z; and (d) fragmentation of unknown compound with a fragment at 779 m/z.