Birth Control Patch Available in Canada
The combined hormonal contraceptive patch available in Canada is Ortho Evra (also known as Evra), which contains norelgestromin 0.6 mg and ethinyl estradiol 0.75 mg, delivering approximately 150 μg norelgestromin and 35 μg ethinyl estradiol daily. 1, 2, 3
Product Details
The patch is a 20 cm² (approximately 1.75 × 1.75 inch) transdermal system that was approved in Canada shortly after its US approval in November 2001 3. It can be applied to:
- Abdomen
- Upper torso (excluding breasts)
- Upper outer arm
- Buttocks
Dosing Regimen
The standard regimen involves:
- One patch applied weekly for 3 consecutive weeks
- One patch-free week (week 4) during which withdrawal bleeding typically occurs
- Each patch is worn continuously for 7 days before replacement 1, 2
Efficacy and Safety Considerations
Typical use failure rate is 9%, similar to combined oral contraceptives 1. However, efficacy may be reduced in women weighing more than 198 pounds (90 kg), with perfect-use failure rates of 0.9% versus 0.3% in lighter women 1.
Important Safety Warning
The patch delivers 1.6 times higher estrogen exposure compared to low-dose combined oral contraceptives 1, 2. This has led to concerns about venous thromboembolism (VTE) risk:
- Studies suggest a possible 1.2 to 2.2-fold increased VTE risk compared to 20-35 μg combined oral contraceptives 2
- The absolute VTE risk remains low, but this should be factored into contraceptive counseling 4
- Other combined hormonal methods may be safer first-line choices, particularly for patients with any VTE risk factors 2
Side Effects
Side effects are comparable to other combined hormonal contraceptives, with additional patch-specific issues 1:
- Breast tenderness
- Headaches
- Nausea
- Breakthrough bleeding
- Application site reactions (hyperpigmentation, contact dermatitis, irritation)
- Patch dislodgement
Clinical Considerations
The patch offers a simpler weekly regimen compared to daily pills, which theoretically improves adherence. However, observational data in adolescents showed only 57% continuation at 1 year with the patch versus 76% with pills 2, suggesting that ease of use alone does not guarantee better outcomes.
Given the higher estrogen exposure and potential VTE risk, the patch should be reserved for patients who specifically prefer this delivery method and have no contraindications to combined hormonal contraception 2. Patients should be counseled about the VTE risk and alternative options including lower-dose combined oral contraceptives, the vaginal ring, or long-acting reversible contraceptives.