Drugs most commonly implicated are penicillin, sulphonamides and thiazide diuretics. Methamphetamine and other sympathomimetics can cause a cerebral vasculitis alongside polyarteritis nodosa like systemic features. With other drugs,there is presence of skin vasculitis with palpable petechiae or purpura. Biopsy of these lesions reveal inflammation of the small vessels, termed leukocytoclastic vasculitis, which is most prominent in postcapillary venules. At least three out of five criteria yields sensitivity and specificity of 71 and 84%:

Age > 16
Use of possible triggering drug in relation to symptoms
Palpable purpura
Maculopapular rash
Skin biopsy showing neutrophils around vesselIgA vasculitis (formerly known as Henoch–Schonlein purpura). Systemic vasculitis due to tissue deposition of IgA-containing immune complexes. Biopsy of lesions shows inflammation of small vessels. It is considered a form of hypersensitivity vasculitis but is distinguished by prominent deposits of IgA. This is the most common vasculitis in children. Presence of three or more criteria yielded sensitivity of 87% while less than two criteria yielded hypersensitivity vasculitis in 74%:

Palpable purpura (usually of buttocks and legs)
Bowel angina
GI bleed
Hematuria
Onset < 20 years
No new medicationsEssential cryoglobulinemic vasculitis. Most often due to hepatitis C infection, immune complexes of cryoglobulins – proteins that consists of immunoglobulins and complement and precipitate in the cold while dissolving upon rewarming – are deposited in walls of capillaries, venules, or arterioles. Therefore, complement will be low with histology showing vessel inflammation with immune deposits. Other/ungrouped
Vasculitis secondary to connective tissue disorders. Usually secondary to systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), relapsing polychondritis, Behçets disease, and other connective tissue disorders. Vasculitis secondary to viral infection.
Eletriptan, sold under the brand name Relpax and used in the form of eletriptan hydrobromide, is a second generation triptan medication intended for treatment of migraine headaches. It is used as an abortive medication, blocking a migraine attack which is already in progress. Eletriptan is marketed and manufactured by Pfizer Inc.

Approval and availability
Eletriptan was approved by the US Food and Drug Administration (FDA) on December 26, 2002, for the acute treatment of migraine with or without aura in adults. It is available only by prescription in the United States and Canada. It is not intended for the prophylactic therapy of migraine or for use in the management of hemiplegic or basilar migraine. It is available in 20 mg and 40 mg strengths. Eletriptan was covered by U.S. Patent no. 5545644 and U.S. Patent  no. 6110940;  both now expired. Mechanism of action
Eletriptan is believed to reduce swelling of the blood vessels surrounding the brain. This swelling is associated with the head pain of a migraine attack. Eletriptan blocks the release of substances from nerve endings that cause more pain and other symptoms like nausea, and sensitivity to light and sound. It is thought that these actions contribute to relief of symptoms by eletriptan. Eletriptan is a serotonin receptor agonist, specifically an agonist of certain 5-HT1 family receptors. Eletriptan binds with high affinity to the 5-HT[1B, 1D, 1F] receptors. It has a modest affinity to the 5-HT[1A, 1E, 2B, 7] receptors, and little to no affinity at the 5-HT[2A, 2C, 3, 4, 5A, 6] receptors.