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You can submit questions regarding selected Merck products for a response from a medical professional. Your question can be submitted online or by telephone. Please select your preferred method of communication below.



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PAH for Injection


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Please do not use this information request to submit an adverse event.
If you wish to report an adverse event with a specific Merck product,
please call the Merck National Service Center at any time at 1-800-672-6372.



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The searchable database may not contain all of the available information on a particular topic. If you cannot find the information you need by searching the online database, please submit a medical question or call the Merck National Service Center by phone at 1-800-672-6372 for immediate assistance.

This service is provided to health care practitioners licensed to practice in the United States. The information provided through this service is for informational purposes and is not intended to promote the use of any product. The information also should not be considered medical advice regarding a specific patient or patient type.

Each health care professional who uses this service retains sole responsibility for decisions regarding patient care. Please review the relevant package insert for important safety information, dosing instructions, and other data before prescribing any medications discussed through this service.

Reporting an Adverse Event or Product Quality Complaint

If there is an emergency or you wish to report and adverse event or product quality complaint with a specific Merck product, please call the Merck National Service Center at any time at:


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