Progestogen Only Injectables
Progestogen only injectables (POI) are widely used in the UK in the form of DMPA (depo medroxyprogesterone acetate) and NET-EN (norethisterone enantate); both are long-acting progestogens. DMPA can be given as a deep intramuscular injection (Depo-Provera 150mg medroxyprogesterone acetate) or as a subcutaneous injection (Sayana Press 104mg medroxyprogesterone acetate). NET-EN is rarely used in the UK. It comes in an intramuscular injection (Noristerat 200mg) and has limited licensing indications.
POI is a highly effective long acting contraception, with failure rate of approximately 0.2% in the first year of use. With typical use, however, failure rate increases to approximately 6%. POI contraception, like CHC, prevents ovulation. It also interferes with cervical mucus production and endometrial proliferation.
As NET-EN is rarely used in the UK, the following guidance, based on FSRH guidance, concerns DMPA (unless stated).