Amlodipine-induced petechial rash

• Reported to be only occurring in 1 – 2% of individuals taking amlodipine
• The likely mechanism is an increase in capillary hydrostatic pressure with dihydropyridines, which selectively relax the precapillary sphincter. The increased hydrostatic pressure causes a few red blood cells to migrate to extravascular space giving the appearance of petechial rash.
• Amlodipine is also a common drug that causes fixed drug eruption, where the eruption can appear within a day to a few weeks of ingesting the causative drug and can occur on any part of the skin or mucous membranes (frequently hands, feet, tongue, penis or perianal areas)
• The site of eruption is fixed, occurring within hours of ingesting the causative drug at exactly the same site.
• Oral challenge is accepted and safe practice to confirm the diagnosis of amlodipine-induced fixed drug eruption.
• Management option would be to withdraw the offending drug, thus facilitating absorption of exuded red cells and resolution to be expeceted over a few weeks time.
• Topical corticosteroids may help reduce the intensity of the reaction.

References:

1. UpToDate. Amlodipine: Drug Information. http://www.uptodate.com.ezp.imu.edu.my/contents/amlodipine-drug-information?source=search_result&search=amlodipine&selectedTitle=1~109
2. ADR Report. Amlodipine-induced petechial rash. http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2011;volume=57;issue=4;spage=341;epage=342;aulast=Murthy
3. Anne Lee and JoDrug-induced skin reactions. http://www.pharmpress.com/files/docs/ADRe2Ch05.pdf