Is there a risk of allergic cross-reactivity between methylprednisolone and prednisolone?/nA patien

Fråga: Is there a risk of allergic cross-reactivity between methylprednisolone and prednisolone? A patient with myasthenia gravis was treated with i.v. 6-methylprednisolone (Solu-Medrol) 8 years ago due to a myasthenic exacerbation. She got difficulties breathing and was referred to the intensive care unit. The episode was interpreted as a hypersensitivity reaction to Solu-Medrol. She now has a nephrotic syndrome and treatment with oral prednisolone is considered.

Sammanfattning: Systemic allergic reactions to glucocorticoids have been described. Allergologic tests are insensitive. There is a pattern of cross-reactivity in contact dermatitis, but it is uncertain to which extent this is true for type-I reactions.

Svar: The question of hypersensitivity cross-reactivity between different glucocorticoids has been answered before (1,2), but both questions concerned patients reacting to intraarticular depot preparations. Most of the literature on cross-reactivity deals with contact dermatitis (i.e. delayed hypersensitivity reactions) and the extrapolation of these findings to type I (i.e. allergic or anaphylactic) reactions is questionable.

One of the lessons from contact dermatitis is that even though the hypersensitivity reaction is often due to other constituents of the preparation, when there is a hypersensitivity to a glucocorticoid, the substitutions at carbon 6 and 9 in the steroid skeleton determine the degree of cross-reactivity (3). According to this, a patient hypersensitive to prednisolone might tolerate 6-methylprednisolone. Since betamethasone, which has no methyl on carbon 6 and has a fluorine atom at carbon 9 and a methyl in beta-position on carbon 16 (4), a cross-reaction might be even less likely between betamethasone and methylprednisolone, if extrapolation from Wilkinson´s et al. (3) findings in type IV hypersensitivity is valid for type I hypersensitivity. However allergic cross-reactivity has been described between prednisolone and dexamethasone (the 16-alpha-isomer of betamethasone). Prick testing has been described to be negative in four cases of anaphylaxia to i.v. prednisolone hemisuccinate and intracutaneus testing was only positive in three of these cases (5). Thus allergologic investigation might not be able to exclude hypersensitivity, but may confirm it.

It is not uncommon for myasthenia gravis patients to initially worsen on glucocorticoid treatment and high-dose treatment may even precipitate myasthenic crisis (6). Upon scrutinizing old medical records, it was found that the respiratory distress was treated with neostigmin and not adrenaline and thus must have been interpreted as a myasthenic crisis rather than anaphylactic shock.

In this case there is probably not a problem of glucocorticoid allergy. Since there has been some concern, it is probably wise to monitor the patient closely and to have adrenaline handy.