Progestogen-only pill potx

68

There are five varieties of progestogen-only pill (POP) available

(Table 8): four are of the old type that variably inhibit ovulation,

while the fifth, Cerazette, is a primarily anovulant product. The

latter is very different and therefore is mainly dealt with at the

end of this section. Unless otherwise stated the abbreviation

POP will refer to the four old-type POPs.

Mechanism of action and maintenance of

effectiveness

The mechanism of action is complex because of variable inter￾actions between the administered progestogen and the endoge￾nous activity of the woman’s ovary. Outside of lactation (when

Progestogen-only pill

Product Constituents Course of

treatment

Table 8

Available POPs

Noriday 350 µg norethisterone 28 tablets

Micronor 350 µg norethisterone 28 tablets

Femulen 500 µg etynodiol diacetate 28 tablets

Norgeston 30 µg levonorgestrel 35 tablets

Cerazette 75 µg desogestrel 28 tablets

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