Endometrial Breakdown Triggers the Dysmenorrhea Cascade
Falling progesterone destabilizes the endometrium at menses onset.
- Menses: Cycle phase (Day 1 onset)
- Progesterone drop: Trigger (Late luteal phase)
- Lysosome release: Tissue event (Membrane breakdown)
- ~50–90%: Affected women (Report dysmenorrhea)
Why shedding starts the pain pathway
Placeholder: falling hormones destabilize endometrial cell membranes, freeing arachidonic acid.
Arachidonic Acid to Prostaglandin via COX Enzymes
COX-1 and COX-2 convert arachidonic acid into PGF2α and PGE2.
- COX-1/COX-2: Key enzyme (Cyclooxygenase)
- PGF2α: Main mediator (Vasoconstrictor)
- Arachidonic acid: Precursor (Membrane phospholipid)
- Day 1–2: Peak levels (Of menstruation)
Synthesis pathway placeholder
Placeholder: phospholipase A2 frees arachidonic acid, COX oxidizes it into prostaglandin precursors.
Prostaglandins Drive Hypercontractile Uterine Spasm
High PGF2α causes sustained myometrial contraction and ischemia.
- >150 mmHg: Pressure rise (Vs. ~80 normal)
- >4–5/10min: Contraction freq (Hypercontractility)
- Uterine ischemia: Result (Reduced blood flow)
- Cramping pain: Symptom (Pelvic/lower back)
Spasm mechanism placeholder
Placeholder: prostaglandins bind myometrial receptors, driving vasoconstriction and painful contractions.
NSAIDs Inhibit COX to Cut Prostaglandin Output
NSAIDs block the COX active site, reducing new prostaglandin synthesis.
- NSAIDs: Drug class (Ibuprofen, naproxen)
- COX active site: Target (Competitive inhibition)
- ↓PG synthesis: Effect (Not existing PG)
- ~30–60 min: Onset (Oral absorption)
Blockade mechanism placeholder
Placeholder: NSAIDs occupy the COX enzyme pocket, preventing further arachidonic acid conversion.
Why Early Dosing Improves Pain Relief Outcomes
Dosing before pain onset blocks synthesis before prostaglandins accumulate.
- Pre-onset: Best timing (1–2 days before)
- Lower relief: Late dosing (PG already high)
- ~70–90%: Relief rate (With early NSAID use)
- Scheduled dosing: Strategy (Not as-needed only)
Timing dependence placeholder
Placeholder: earlier NSAID timing prevents the prostaglandin surge rather than reversing it.
Placeholder: start NSAIDs before pain begins for the strongest relief effect.