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Progestin

Norethindrone Acetate (often combined with Estradiol in brands like Lopreeza) is a hormone therapy used primarily by postmenopausal women. It helps treat hot flashes, vaginal dryness, and can help prevent bone loss (osteoporosis). Because it contains hormones, it carries serious warnings regarding risks of blood clots, stroke, heart attack, and certain cancers.

How it worksThis medication works by mimicking the action of progesterone, a natural hormone in the body, by binding to progesterone receptors.

Brand names:AYGESTIN, NORLUTIN, NORLUTATE, ORIAHNN (COPACKAGED)

Used for
Moderate to severe hot flashes (vasomotor symptoms) due to menopausePrevention of bone loss (osteoporosis) after menopauseModerate to severe vaginal and vulvar dryness due to menopause
Conditions
Menopause-related symptomsPostmenopausal osteoporosis
Class
HormoneProgestinEstrogenReproductive systemCardiovascular systemSkeletal system

How to take

FormsOral tablet
RoutesOral

One tablet is taken once daily. It is recommended to use the lowest effective dose for the shortest time possible to meet treatment goals.

When using Lopreeza for vaginal dryness alone, doctors may suggest topical vaginal products instead. For osteoporosis prevention, it should only be used by women at significant risk, and other non-hormone options should be considered.

Key warnings

This drug carries a boxed warning because it may increase the risk of serious cardiovascular issues (like blood clots, stroke, and heart attack), breast cancer, endometrial cancer, and possibly dementia. It should not be used to prevent heart disease or dementia.

  • ·This drug carries a boxed warning because it may increase the risk of serious cardiovascular issues (like blood clots, stroke, and heart attack), breast cancer, endometrial cancer, and possibly dementia. It should not be used to prevent heart disease or dementia.
  • ·Increased risk of blood clots, stroke, and heart attack.
  • ·Increased risk of gallbladder disease.
  • ·Stop use immediately if you experience severe high calcium, loss of vision, severe high triglycerides, or jaundice.
  • ·Monitor thyroid function if you are also taking thyroid replacement medicine.

Do not use if

  • ·Undiagnosed abnormal vaginal bleeding
  • ·Known or suspected history of breast cancer
  • ·Known or suspected estrogen-dependent tumors
  • ·Active blood clots (DVT or PE) or a history of them
  • ·Active heart disease (stroke or heart attack) or a history of them
  • ·Liver disease or impairment
  • ·Certain blood clotting disorders (like protein C or S deficiency)
  • ·Known pregnancy

Side effects

Common

Back painHeadacheNauseaDiarrheaInsomniaWeight gainBreast painEmotional changes

Serious

  • ·Blood clots (DVT or PE)
  • ·Stroke
  • ·Heart attack (MI)
  • ·Gallbladder disease
  • ·Breast cancer
  • ·Endometrial cancer
  • ·Severe vision changes
  • ·Jaundice (yellowing of skin/eyes)

Seek help if

  • ·Sudden loss of vision
  • ·Severe headache
  • ·Chest pain or signs of heart attack
  • ·Signs of stroke
  • ·Pain, swelling, or redness in a leg
  • ·Yellowing of skin or eyes

Interactions

  • ·Certain medications that affect liver enzymes (CYP3A4) can change how the body processes these hormones.
  • ·Inducers like St. John's wort, phenobarbital, carbamazepine, and rifampin may make the medicine less effective.
  • ·Inhibitors like erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and grapefruit juice may increase hormone levels and lead to more side effects.
  • ·Known interacting drugs include Crinone, Desogen, Danocrine, Nor-QD, Provera, Slynd, Ovulen, Korlym, Delalutin, and Megace.
FoodTaking Lopreeza 1 mg/0.5 mg with food does not change how the body absorbs the estradiol.

Special populations

PregnancyDo not use this medication if you are pregnant. While there is little evidence of increased birth defect risks from accidental early use, it is not intended for use during pregnancy.

BreastfeedingDo not use this medication while breastfeeding. Estrogen can decrease the amount and quality of breast milk, and hormones can be found in the milk of nursing women.

PediatricThis medicine is not for use in children.

GeriatricThere is not enough information to determine how women over 65 respond differently than younger women, but studies have shown an increased risk of stroke and invasive breast cancer in women over 65 using certain estrogen/progestin combinations.

Talk to your doctor

Monitor

  • ·Thyroid function
  • ·Blood pressure
  • ·Vision changes
  • ·Signs of blood clots
  • ·Gallbladder symptoms
  • ·Vaginal bleeding

Questions to ask

  • ·Am I at risk for blood clots or stroke?
  • ·Is this the lowest effective dose for my symptoms?
  • ·Should I use a topical cream instead of a tablet for vaginal dryness?
  • ·How will this affect my bone density?

Pharmacokinetics

OnsetNorethinrone reaches peak levels in 0.5 to 1.5 hours; Estradiol reaches peak levels in 5 to 8 hours.
BioavailabilityEstradiol oral bioavailability is 53% compared to a combination oral solution.
MetabolismEstradiol is partially metabolized by cytochrome P450 3A4 (CYP3A4).

Practical

OverdoseAn overdose may cause nausea, vomiting, breast tenderness, stomach pain, sleepiness, fatigue, or withdrawal bleeding. Treatment involves stopping the medication and managing symptoms.

Ingredients

Allergens

lactose

Inactive

lactose monohydratestarch (corn)copovidonetalcmagnesium stearatehypromellosetriacetinhydroxypropylcellulose

Educational summary derived from FDA labeling, AI-assisted. Not medical advice — consult a healthcare professional. Updated 2026-04-25.