The Injectable Contraceptives contain synthetic female hormones. When administered intramuscularly of subcutaneously, these are slowly released into the blood stream and provide protection from pregnancy for a long duration.
There are two main types of injectable contraceptives:
1) Progestogen-only Injectables (POI), containing only synthetic progesterone. They are of two types:
a) Depot MedroxyProgesterone Acetate (DMPA) – 3 monthly Injection. This can be given through:
• Intramuscular route (DMPA-IM) or
• Subcutaneous route (DMPA-SC).
b) Norethisterone enanthate (NET-EN) – 2 monthly Injection.
2) Combined Injectable Contraceptive (CIC): containing estrogen (usually ethinylestradiol) and progesterone; need monthly injection.
Under the National Family Planning program, only DMPA injectable contraceptives (both IM and SC formulations) have been added to the basket of choice at present.
Intramuscular DMPA is available as:
• Single dose vial with disposable syringe and needle or
• Prefilled syringe with needle
Subcutaneous DMPA is available as a Prefilled auto disable syringe (Uni-ject system; where squeezing the bulb pushes the fluid through the needle)
Composition of DMPA-IM and DMPA-SC
17 alfa – hydroxyprogesterone derivative of progestin, known as ‘medroxyprogesterone acetate’
Mechanism of action:
Both Subcutaneous-MPA and Intramuscular-MPA have similar mechanism of action. They act by:
1. Inhibiting ovulation - by suppressing mid cycle peaks of LH and FSH
2. Thickening of cervical mucus - due to depletion of oestrogen. The thick mucus prevents sperm penetration into the upper reproductive tract.
3. Thinning of endometrial lining - due to high progesterone and depleted oestrogen, making it unfavourable for implantation of fertilized ovum.
Failure rate:
0.3 Per HWY
Storage of DMPA vials:
At temperature between 15⁰C to 30⁰ C in a dry, dust free place.
Do not expose to extreme heat and cold.
Do not keep the injection vials in the refrigerator/freezer
Keep in a cupboard away from direct sunlight.
Dose:
150 mg for IM-DMPA
104 mg for SC-DMPA
The formulation for subcutaneous injection provides slower and more sustained absorption of the progestin than intramuscular MPA. This enables a 30 percent lower dose of progestin via s/c route
Route of administration:
Intramuscular for DMPA-IM
Sub-cutaneous for DMPA-SC
• Subcutaneous MPA is available as a single dose in prefilled auto disable injection device (Uniject system).
• This Uniject system has a thermoformed plastic reservoir with ultra-thin needle attached. It is designed for single use and immediate disposal as it has a one-way valve and collapsible reservoir that cannot be re-filled.
Site of injection:
• For IM injection: the preferred site is the deltoid muscle. Otherwise gluteal muscle or outer-anterior thigh may also be used. Do not massage the injection site.
• For SC injection: the site used is the
o Outer anterior portion of thigh
o Abdomen (below umbilicus) or
o Upper outer portion of arm.
Post injection instructions:
• Instruct her not to massage or apply hot fomentation to the injection site as the drug needs to stay there for a long time and release very slowly for the next three months.
• Instruct her to come after 90 days for a repeat injection and give her the scheduled date.
• Hand over the DMPA Client Card to her after explaining its content to her.
• Inform the client that the effect of injection is
o Immediate if given between ‘day one’ to ‘day seven’ of her menstrual cycle
o A backup contraceptive method (e.g. condom) should be used for 7 days, if given after day 7 of the cycle
Follow up of defaulters:
A defaulter is a client who does not return for the next injection on the scheduled date but comes for it within the grace period (grace period is 2 weeks earlier and up to 4 weeks later from the scheduled date).
• Give DMPA, no back up is required
Follow up of drop outs:
A dropout is a DMPA client who comes for the next injection after the grace period of 4 weeks is over i.e. more than 4 months have passed since she took her last injection
• Rule out pregnancy
• If not pregnant, give DMPA Injection
• Advise back up method (e.g. Condom) for next 7 days
The use of progestogen-only contraceptive has no adverse effect on the quantity, quality and composition of breast milk as well as duration of lactation, once breast feeding has been established.
Therefore, WHO recommends the use of DMPA after 6 weeks post-partum, if a woman is fully or partially breast feeding
Advantages of DMPA
Contraceptive benefits:
• May be used by women at any age or parity.
• Safe, highly effective and long term contraception – Acts for 3 months with a grace period of 4 weeks.
• Convenient and easy to use (does not require daily routine or additional supplies).
• Completely reversible: 7-10 months from date of last injection
• A private and confidential method.
• Does not interfere with sexual intercourse.
• Pelvic examination not required prior to use.
• Suitable for women in whom oestrogen containing contraceptive is contraindicated.
• Suitable for breast feeding women (after 6 weeks postpartum) as it does not affect quantity, quality and composition of breast milk.
Non contraceptive benefits:
• May decrease menstrual cramps and reduce pre-menstrual syndrome
• Improves anaemia by reducing menstrual blood loss due to menstrual changes such as amenorrhea.
• Reduces the symptoms of endometriosis.
• Decreases benign breast disease and ovarian cyst.
• Helps prevent uterine tumours (fibroids).
• Reduces the incidence of symptomatic pelvic inflammatory disease (PID).
• Protect against endometrial cancer and possibly ovarian cancer.
• Reduces sickle-cell crises in women with sickle cell anaemia.
• Protects against ectopic pregnancy (since ovulation does not occur).
• Minimal drug interactions – no demonstrable interaction has been found between DMPA and antibiotics/enzyme-inducing drugs.
Limitations of DMPA
• It does not protect against STI/RTI and HIV infection.
• Once taken its action cannot be stopped immediately.
• It causes changes in the menstrual cycle and bleeding
• It has to be repeated every three months.
• Return of fertility takes 7-10 months from date of last injection (Average 4-6 months after 3 months effectivity of last injection is over).
Switching from MPA- SC to MPA- IM or Vice Versa
As the active ingredient in the IM and SC is identical, it is safe to switch back and forth between IM and SC every three months with the same level of contraceptive protection.
This switching is safe and it does not decrease effectiveness. If switching is necessary, the injection of the alternate mode should be administered on the due date and duly recorded
However, MPA-SC should not be used for IM administration and similarly MPA-IM should not be used for MPA-SC administration.
References:
1. GOI March 2016. Reference Manual for Injectable Contraceptive (DMPA). Family Planning Division Ministry of Health and Family Welfare. New Delhi
2. GOI December 2016. Supplement for Medroxy Progesterone Acetate – subcutaneous (MPA – SC). Family Planning Division Ministry of Health and Family Welfare. New Delhi
3. Park K. Demography and family planning. In: Park K. Park's Textbook of Preventive and Social Medicine, 24th ed. Jabalpur, India: Banarsidas Bhanot Publishers, 2017; pp. 525-52.
4. Chapter 1-contraceptives; In: Mastering Practicals – Community Medicine. 2nd ed. Eds. Tiwari P, Tiwari S. Lippincott Williams & Wilkins; Wolters Kluwer, New Delhi