A Phase 4 interventional study of Acetaminophen 1000mg PO and IV Acetaminophen 1000mg in Pelvic Pain, sponsored by Montefiore Medical Center. Not yet recruiting at 1 site in United States. Open to female participants aged 16 Years to 50 Years. Per ClinicalTrials.gov, last updated 2026-09-23.
Sponsored by Montefiore Medical Center · Phase 4, Interventional, and Treatment
The investigator team proposes a randomized, double-blind, double-dummy comparative effectiveness trial conducted in two urban emergency departments (EDs) in the Bronx, New York. This study is designed to determine the relative efficacy of IV acetaminophen compared to PO acetaminophen in treating pelvic pain. This design focuses on the early onset of action and short-term efficacy, which may better capture potential differences between IV and PO acetaminophen in the acute ED setting.
An estimated 70% of Emergency Department (ED) visits involve pain as a complaint. Although ED practice has shifted away from routine opioid prescribing, uncertainty remains regarding optimal selection among commonly used non-opioid analgesics such as nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen. Medication selection varies by pain etiology, and among patients presenting with musculoskeletal pain, opioids (40.7%), acetaminophen (37.8%), and NSAIDs (22.6%) remain the most frequently administered medications in the ED.
Pain in women has been comparatively understudied. Pelvic pain is common among women of childbearing age, and chronic pelvic pain affects up to 24% of women overall. In nonpregnant women, NSAIDs are widely considered first-line therapy for both acute and chronic pelvic pain. In pregnant women and in those attempting to conceive, NSAIDs are typically avoided. Observational studies have associated NSAID use around the time of conception or prior to 20 weeks' gestation with an increased risk of miscarriage, while acetaminophen has not shown a similar association. NSAID exposure in early pregnancy has also been linked to congenital anomalies.
Guidelines recommend limiting opioid use during pregnancy and in women of childbearing age. Opioid exposure has been associated with congenital anomalies and with poorer maternal and neonatal outcomes. As a result, opioids are generally avoided as first-line therapy for pelvic pain in patients who are pregnant or may be pregnant.
Therefore, it is routine to ascertain pregnancy status prior to administering NSAIDs or opioids to women of childbearing age for an informed decision making discussion. Acetaminophen, in contrast, is generally considered safe in pregnancy and can be administered without delay while awaiting pregnancy testing. Acetaminophen is associated with relatively mild side effects, which may vary by route of administration.
Pharmacokinetic studies demonstrate that intravenous acetaminophen achieves higher peak plasma concentrations and faster central nervous system penetration than oral administration. Outside the ED, IV acetaminophen has been associated with faster onset of meaningful pain relief and reduced opioid use in some surgical populations. Whether these pharmacologic advantages translate into clinically meaningful improvements in acute pelvic pain management in the Emergency Department for patients of childbearing potential with pelvic pain is unclear.
The investigator team hypothesizes that among women aged 16-50 presenting to the emergency department with pelvic pain, patients receiving intravenous acetaminophen will achieve a greater improvement in the numeric rating scale (NRS) pain score at 30 minutes compared with oral acetaminophen.
375 studies on the registry are indexed under Pelvic Pain; 89 are open to participants now.
This study's planned enrollment of 140 is above the median of 60 across 277 interventional studies indexed under Pelvic Pain.
Browse Pelvic Pain studies →Montefiore Medical Center is the lead sponsor of 416 studies on the registry; 69 are open to participants now.
Of its 87 completed or terminated interventional studies of FDA-regulated products, 76 (87%) have results posted.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Oral Acetaminophen 1000mg + IV placebo Oral Acetaminophen 1000mg No additional analgesics will be administered prior to two hours unless clinically indicated. Rescue analgesia may be administered at any time at the discretion of the treating clinician.
Drug: Acetaminophen 1000mg PO · Other: IV Placebo
Intravenous Acetaminophen + PO placebo IV Acetaminophen 1000mg No additional analgesics will be administered prior to two hours unless clinically indicated. Rescue analgesia may be administered at any time at the discretion of the treating clinician.
Drug: IV Acetaminophen 1000mg · Other: PO Placebo
Oral Acetaminophen 1000mg
Intravenous Acetaminophen 1000mg
IV placebo administration
Oral placebo administration
Mean Change in Numeric Rating Scale (NRS) score
Mean Change in NRS score will be assessed at 30 minutes post-treatment. The NRS is a patient self-assessment pain scale that instructs patients to use a facial grimace scale ranging from 0-10 rating to express pain intensity, wherein 0 is "No pain" and 10 is "Worst pain possible," such that higher scores are indicative of greater pain intensity. For purposes of the primary outcome change in NRS score from baseline will be assessed. Results will be summarized by study arm using descriptive statistics.
Time frame: From baseline to 30 minutes following medication administration
Pain Intensity
Participants will be asked to serially assess their current level of pain intensity as either "Severe," "Moderate," "Mild," or "None." Categorical assessments of pain intensity will be summarized by study arm at each prespecified timepoint.
Time frame: 0-, 5-, 10-, 15-, 30-, 45-, 60- and 120-minutes following medication administration
Time to Clinically Meaningful Reduction in Pain
Time to clinically meaningful pain reduction as assessed by the Numerical Rating Scale (NRS). The NRS is a pain scale that uses a 0-10 rating to measure pain intensity, where 0 is "No pain" and 10 is "Worst pain possible." Clinically meaningful pain reduction will be defined as achieving a reduction in NRS score of ≥1.3 from baseline. Results will be summarized by study arm using basic descriptive statistics.
Time frame: Within 2 hours after medication administration
Use of Rescue Medications
The number/percentage of patients requiring rescue analgesia of any type within 120 minutes will be summarized by study arm using basic descriptive statistics.
Time frame: Within 2 hours following medication administration
Patient Global Impression of Change (PGI-C) Score
Effectiveness of treatment will be evaluated using the PGI-C scale. The PGI-C scale is a 7-point self-reported scale used to assess the patient's perception of change in condition/health status following treatment. Patients will provide a single response as to their self-perception of change in condition/health status on a scale ranging from 1 ("Very much improved") to 7 ("Very much worse)" with 4 representing "No change" as the midpoint. Lower scores are indicative of an improved self-assessment of condition following treatment. Scores will be summarized by study arm using descriptive statistics.
Time frame: 30- and 120-minutes following medication administration
Treatment-Related Adverse Events (TRAEs)
All treatment-related adverse events occurring within 2 hours of medication administration will be recorded and summarized by study arm.
Time frame: Within 2 hours following medication administration
Emergency Department (ED) Disposition
ED disposition will be summarized at 2 hours. Patients will be categorized as either having been admitted, discharged, or status yet to be determined. Categorical data will be summarized by study arm.
Time frame: At 2 hours following medication administration
Length of Stay (LOS)
Length of stay will be determined based on the time interval between arrival in the ED and disposition determination. Mean LOS will be summarized by study arm.
Time frame: Less than 24 hours following medication administration
Patient Satisfaction
Patient satisfaction will be determined by asking patients whether they would prefer the same medication which was administered during the study if they returned to the ED with the same condition. The number/percentage of patients who prefer the same medication will be summarized by study arm.
Time frame: At 2 hours following medication administration
Plan to share: No
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Studies of the drug tested here: Acetaminophen