formulations

Last reviewed 01/2018

Two varieties exist:

• monophasic / fixed pill
• multiphasic / varying dose pill

The pattern of usage of the fixed pill depends on the exact preparation. In the most common regimen, pills are first taken on day 5 of a cycle and continued for 21 days. The tablets then either are discontinued for 7 days, or a placebo is taken for 7 days, during which time, withdrawal bleeding may sometimes occur. It is recommended that the pill is taken at the same time each day - usually bedtime - and if omitted, taken the next morning. The patient should be warned that ovulation may not be inhibited in the first cycle of treatment.

Multiphasic preparations contain tablets with varying amounts of oestrogen and progesterone. They aim to simulate a more natural hormonal pattern. The oestrogen content increases from 30 mcg ethinyloestradiol in the first six days to 40 mcg for the next five days, then back to 30 mcg for ten days. The progestogen - levonorgestrel - is increased from 50 mcg to 75 mg to 100 mcg in three stages. It was hoped that variable dose pills would be less likely to cause thromboembolism, but this is yet to be established.