Alternatively, longer durations of active hormone, designed to minimize the number of withdrawal episodes, have similar eicacy and safety proiles as more traditional administration (Edelman, 2014). These extended-cycle products produce a 13-week cycle, that is, 12 weeks of hormone use, followed by a week for withdrawal menses. The product Amethyst provides continuous active hormone pills for 365 days each year. Such extended or continuous regimens may be especially suited for women with significant menstrual symptoms (Mendoza, 2014).
For general initiation, women ideally begin COCs on the first day of a menstrual cycle. In such cases, a supplementary contraceptive method is unnecessary. With the more traditional "Sunday start," women begin pills on the irst Sunday that follows menses onset, and an additional method is needed for 1 week to prevent conception. If menses begin on a Sunday, then pills are begun that day and no supplemental method is required. Alternatively, with the "quick start" method, COCs are started on any day, commonly the day prescribed, regardless of cycle timing. An additional method is used during the first week (Westhof, 2002, 2007b). If the woman is unknowingly already pregnant during quick start initiation, COCs are not teratogenic (Lammer, 1986; Rothman, 1978; Savolainen, 1981). However, a missed menses following COC initiation should prompt pregnancy testing. Similar same-day initiation can be implemented with the contraceptive vaginal ring or patch (Murthy, 2005; Schafer, 2006).
For maximum eiciency, pills are best taken at the same time each day. If one dose is missed, the missed pill is taken immediately; the scheduled dose for that day is taken on time; and then daily pills are continued. If two or more doses are missed, the most recent missed pill is taken immediately; the scheduled dose for that day is taken on time; and an efective barrier technique used for 7 days while daily pills are then continued (Curtis, 2016a). If withdrawal bleeding fails to occur during the pill-free interval, a woman should continue her pills but seek attention to exclude pregnancy.
With initiation of COCs, spotting or bleeding is common.
It does not relect contraceptive failure and typically resolves within one to three cycles. If unscheduled bleeding persists, those with bleeding during the first part of a pill pack may beneit from an increase in the estrogen dose, whereas those with bleeding during the second part may improve with a higher progestin dose (Nelson, 2011).
Some drugs decrease COC efectiveness, and choosing another contraceptive method is preferable. However, if a COC is selected for concurrent use in these instances, a preparation containing a minimum of 30 �g ethinyl estradiol is ideally chosen. Conversely, some COCs interfere with the actions of certain drugs (see Table 38-2).
In obese women, COCs are efective (Lopez, 2016). Some studies point to lowered hormone bioavailability, but over all eicacy remains high (Nakajima', 2016; Westhof, 2010;
Yamazaki, 2015). With the transdermal patch method, how ever, evidence is more robust that obesity may alter pharmaco kinetics and lower eicacy, as discussed on page 692.