Can promethazine be administered intramuscularly (IM) in the deltoid muscle?

Promethazine Intramuscular Administration in the Deltoid Muscle

Promethazine should not be administered intramuscularly in the deltoid muscle. The preferred parenteral route for promethazine is deep intramuscular injection, but specifically in larger muscle groups like the vastus lateralis (thigh) rather than the deltoid. 1

Administration Guidelines for Promethazine

FDA-Approved Administration Routes

• Promethazine hydrochloride injection can cause severe chemical irritation and tissue damage regardless of administration route 1
• The FDA drug label specifically states that the preferred parenteral route for promethazine is deep intramuscular injection, without specifying the deltoid as an appropriate site 1
• Subcutaneous injection is contraindicated due to risk of tissue necrosis 1
• Intra-arterial injection is absolutely contraindicated due to severe arteriospasm risk and possible gangrene 1

Risks of Deltoid Administration

• Adverse reactions including burning, pain, thrombophlebitis, tissue necrosis, and gangrene can occur with inadvertent perivascular extravasation, unintentional intra-arterial injection, and intraneuronal or perineuronal infiltration 2
• The deltoid muscle is relatively small and has proximity to important neurovascular structures, increasing risk of complications 3
• Intramuscular injections in the deltoid have been shown to be inferior to other sites for certain medications, suggesting potential bioavailability issues 4

Preferred Intramuscular Injection Sites

Vastus Lateralis (Thigh)

• The middle of the vastus lateralis is considered an appropriate site for intramuscular injections due to low risk of vascular or nerve damage 3
• This site is distant from major blood vessels and nerves, making it safer for medications that can cause tissue irritation 3

Ventrogluteal Site

• The ventrogluteal site is another appropriate alternative for intramuscular administration of medications like promethazine 5
• This site provides adequate muscle mass for deep intramuscular injection while minimizing risk to major neurovascular structures 5

Special Considerations

Clinical Context

• For anaphylaxis management, when epinephrine is administered intramuscularly, the anterolateral thigh (vastus lateralis) produces higher and more rapid peak plasma levels compared with injections administered intramuscularly or subcutaneously in the arm (deltoid) 2
• This pharmacokinetic principle may apply to other medications as well, suggesting potential absorption differences between deltoid and larger muscle groups 2

Medication-Specific Guidelines

• Some medications have specific administration site recommendations in their package inserts 5
• For promethazine specifically, the FDA label does not recommend the deltoid as an injection site, focusing instead on deep intramuscular injection without specifying the exact muscle 1

Practical Recommendations

• When administering promethazine intramuscularly, use the vastus lateralis (thigh) or ventrogluteal site rather than the deltoid 1, 3, 5
• Ensure proper technique with deep intramuscular injection to minimize risk of tissue damage 1
• The standard adult dose of promethazine for allergic conditions is 25 mg intramuscularly 1
• For sedation in hospitalized adults, 25-50 mg may be administered intramuscularly 1
• For nausea and vomiting control, 12.5-25 mg is recommended, not to be repeated more frequently than every four hours 1

In conclusion, based on the FDA drug labeling and clinical evidence, promethazine should not be administered intramuscularly in the deltoid muscle due to safety concerns and risk of tissue damage. The vastus lateralis or ventrogluteal sites are preferred for intramuscular administration of this medication.