How to write a prescription for Lo Loestrin Fe (norethindrone acetate and ethinyl estradiol)?

How to Write a Prescription for Lo Loestrin Fe

Write Lo Loestrin Fe as: norethindrone acetate 1 mg/ethinyl estradiol 10 mcg (24 active tablets) + ethinyl estradiol 10 mcg (2 tablets) + ferrous fumarate 75 mg (2 tablets); take 1 tablet orally daily at the same time for 28 days, then start new pack immediately.

Prescription Components

Drug Name and Formulation

• Brand name: Lo Loestrin Fe
• Generic components: Norethindrone acetate/ethinyl estradiol with ferrous fumarate 1
• Specific dosing regimen: 24/2/2 formulation (24 active hormone tablets, 2 estrogen-only tablets, 2 iron tablets) 2

Standard Prescription Format

Rx: Lo Loestrin Fe

• Dispense: #28 tablets per pack (specify number of packs, typically 3-12 months)
• Sig: Take 1 tablet by mouth daily at the same time each day for 28 days, then start new pack immediately without interruption
• Refills: As appropriate (typically 11 refills for annual supply)

Key Prescribing Details

Dosing instructions:

• One tablet daily at the same time every day 1
• The 24/4 regimen provides better follicular suppression during the hormone-free interval compared to traditional 21/7 regimens 3, 2
• No pill-free interval between packs—start new pack immediately after completing 28-day cycle 2

Patient age considerations:

• Approved for women ≥15 years of age for contraception 1
• Safety and efficacy not established in pre-menarchal patients 1

Baseline Requirements Before Prescribing

Mandatory screening:

• Confirm pregnancy status (negative pregnancy test) 1
• Measure baseline blood pressure 1
• Assess for absolute contraindications 1

Absolute contraindications to document absence of:

• Active or history of thromboembolic disease (DVT, PE, stroke, MI) 1
• Breast cancer or estrogen-sensitive malignancies 1
• Undiagnosed abnormal uterine bleeding 1
• Hepatic disease or hepatic tumors 1
• Pregnancy 1
• Age ≥35 years with smoking history 1
• Uncontrolled hypertension 1

Clinical Pearls for Lo Loestrin Fe

Advantages of this formulation:

• The 24-day active regimen reduces breakthrough bleeding compared to 21-day regimens with the same hormone combination 2
• Significantly fewer intracyclic bleeding days (0.95 vs 1.63 days) and fewer withdrawal bleeding days (2.66 vs 3.88 days) compared to 21-day norethindrone acetate/ethinyl estradiol formulations 2
• Better cycle control with 78.6% of women experiencing regular withdrawal bleeding in Cycle 1 3

Important counseling points:

• Nearly half of women may not experience withdrawal bleeding by Cycle 13, which is expected and not concerning if pregnancy is ruled out 3
• The ferrous fumarate tablets (last 2 tablets) have no therapeutic contraceptive benefit but help maintain daily pill-taking routine 3
• Extended active hormone duration provides better suppression of follicular development, beneficial for menstrual-related symptoms like dysmenorrhea or heavy bleeding 3

Monitoring Requirements

Ongoing assessment:

• Monitor blood pressure at follow-up visits 1
• Assess for changes in health status, particularly cardiovascular or thromboembolic symptoms 1
• Evaluate breakthrough bleeding patterns and patient satisfaction 2

Drug Interactions to Document

Major interactions requiring alternative contraception or dose adjustment:

• Antibiotics (rifampin, rifabutin) significantly reduce efficacy 1
• Anticonvulsants (carbamazepine, phenytoin, topiramate, barbiturates) 1
• HIV protease inhibitors (ritonavir, nelfinavir) 1
• St. John's wort 1
• Hepatitis C antivirals (particularly sofosbuvir/velpatasvir/voxilaprevir combinations) 4

Common Pitfalls to Avoid

• Do not prescribe without confirming negative pregnancy status and blood pressure measurement 1
• Do not overlook cardiovascular risk factors, particularly in women ≥35 years who smoke 1
• Do not dismiss absence of withdrawal bleeding as treatment failure—this is expected with extended regimens 3
• Do not forget to counsel about backup contraception during the first 7 days of initial use 2