Progesterone Only Injectable

Question 1

What are the 3 methods of progestogen only contraception?

Answer 1

Progestogen-only method of contraception:

1. Progestogen-only pill
2. Progestogen-only implant
3. Progestogen-only injection

Question 2

Briefly describe the mechanism of action of the progestogen-only injection

Answer 2

• Progestogen-only injectables (depot medroxyprogesterone acetate and norethisterone enantate) prevent pregnancy by the inhibition of ovulation and thickening of the cervical mucus, thereby presenting a barrier for sperm penetration.
• In addition, changes to the endometrium make it an unfavourable environment for implantation.

Question 3

What is the most common regime for progesterone-only injection?

Answer 3

• Three progestogen-only injectables are currently available in the UK however Depo-Provera® is the most commonly used progestogen-only injectable and is licensed for long-term use.
• It is given every 12 weeks by deep intramuscular injection.

Question 4

What are the indications for the progesterone-only injection?

Answer 4

• Contraception for women in whom estrogen-containing contraceptives are contraindicated

Question 5

What are the advantages of the progesterone-only injection?

Answer 5

• Very effective
• Users do not have to think about contraception for as long as the injection lasts
• Sex need not be interrupted to use contraception
• Can be used when breastfeeding
• No known interactions with any medications (including liver enzyme-inducing drugs)
• May reduce heavy painful periods and help with premenstrual symptoms
• Can be used in situations where combined hormonal contraceptives are not recommended
• Can be used by women with a BMI greater than 35 kg/m²
• May reduce the risk of ovarian and endometrial cancer

Question 6

What are the disadvantages of progesterone-only injection?

Answer 6

• It is not rapidly reversible→ after stopping use of progestogen-only injectables
  
  • There could be a delay of up to 1 year in the return of normal fertility.
  • Menstruation can take several months to return to normal.
• Does not protect against STIs
• Adverse effects including unscheduled bleeding and weight changes may occur

Question 7

What are the side effects of the progesterone-only injections?

Answer 7

• Menstrual irregularities
• Weight gain
• Injection site reaction e.g. pain, abscess and scarring

Question 8

What are the risks of the progesterone-only injection?

Answer 8

• Breast cancer
• Effect on bone minderal density (BMD)

Question 9

What is the efficacy of the progesterone-only injection?

Answer 9

• Used perfectly→ 0.2% of women will conceive within the first year of use due to method failure
• Used typically→ 6% of women will conceive within the first year of use due to method failure or user failure

Question 10

What contra-indications are associated with progesterone-only injection?

Answer 10

• Acute porphyrias
• Breast cancer
• Genital cancer
• History during pregnancy of idiopathic jaundice
• History of thromboembolism
• Undiagnosed vaginal bleeding

Question 11

Briefly describe the assessment for progesterone-only injection

Answer 11

• Check the UK Medical Eligibility Criteria
• Check the woman’s cervical screening history to ensure that she has attended routine screening appointments
• Assess the woman’s risk of osteoporosis