What are the doses of methylprednisolone, acetaminophen, and antihistamines as pretreatment medications before rituximab injection in an adult patient with pemphigus vulgaris?

Premedication Doses for Rituximab in Pemphigus Vulgaris

For adult patients with pemphigus vulgaris receiving rituximab, premedicate with methylprednisolone 100 mg intravenously (or equivalent) 30 minutes prior to each infusion, along with acetaminophen and an antihistamine before each infusion. 1

Specific Dosing Regimen

Corticosteroid Premedication

• Methylprednisolone 100 mg IV administered 30 minutes before rituximab infusion 1
• This is the FDA-approved dose specifically for RA, GPA, MPA, and pemphigus vulgaris patients 1

Antipyretic (Acetaminophen)

• Acetaminophen 650-1000 mg orally 2
• Should be given before each rituximab infusion 1
• The ESMO guidelines for rituximab specifically recommend paracetamol (acetaminophen) as the antipyretic component 2

Antihistamine

• Diphenhydramine 25-50 mg (oral or IV) or equivalent 2
• Alternative: any H1 antihistamine at standard dosing 1
• Should be administered before each infusion 1

Timing and Administration

The premedication sequence should follow this order:

• Administer methylprednisolone 100 mg IV 30 minutes prior to rituximab 1
• Give acetaminophen and antihistamine before each infusion (timing can overlap with corticosteroid administration) 1

Rationale for Premedication

Rituximab carries a 77% incidence of infusion reactions on first administration, with 10% being severe reactions 2. The premedication regimen significantly reduces these risks:

• The combination of antipyretic and antihistamine is mandatory for all rituximab infusions 2
• Corticosteroid premedication is specifically required for pemphigus vulgaris patients per FDA labeling 1
• This differs from oncology indications where corticosteroids plus antihistamines showed superior protection compared to antihistamines alone (reducing grade 3-4 reactions from 4.7% to 1% with cetuximab) 2

Important Clinical Considerations

A slow initial infusion rate is essential in addition to premedication to minimize cytokine release syndrome 2. The infusion reactions are typically related to cytokine release from B lymphocytes rather than true IgE-mediated allergy 2.

The premedication doses remain consistent for all rituximab infusions in pemphigus vulgaris, including the initial 1000 mg doses given 2 weeks apart, the 500 mg maintenance doses at month 12 and every 6 months thereafter, and the 1000 mg relapse treatment doses 1.