ORAL CONTRACEPTIVES AND ANTIBIOTICS

15 May

The concern regarding oral contraceptives and  antibiotics is essentially theoretical, owing  to the action  of broad-spectrum antibiotics, which  reduce the gut flora bac- teria and  thus  may result  in decreased absorption of estrogen. This could  lead to a possible reduction in the efficacy of oral contraceptives, although pharmacokinetic studies suggest that  serum levels of estrogen are unaffected by antibiotics such  as tetracycline, doxycycline, and  others  (52,53). Nevertheless, there  have  been  very few reports in the  literature of pregnancies associated with  the  use  of antibiotics

in conjunction with  oral  contraceptives (54,55). Existing  reports have  focused on tetracycline, and  the  incidence was  1.2 to  1.4 pregnancies/100  woman years  of use  of  the  oral  contraceptive.  These  data   are  no  greater than   the  background failure  rate  of oral contraceptives (54,55).

NEWER FORMS OF CONTRACEPTIVES

Recently,  newer forms  of contraceptives have  been  developed, such  as contracep- tive patches, vaginal rings,  and  injectable  combination hormones. Each of these  is designed to suppress ovulation and in this regard will lower the ovarian production of androgens. As of yet, these  formulations have not been studied in the treatment of acne.  The contraceptive patch  (Ortho  Evra)  contains 20 mg of ethinyl estradiol and  150 mg of the  progestin, norelgestromin. The  patch  is worn  for three  weeks and  removed for  one  week,  during which   time  menstrual bleeding will  occur. The advantages of this  formulation are  better  patient compliance, dosing that  is not affected  by gastrointestinal disturbances, and  more  consistent serum levels of estrogen serum levels  compared to oral dosing (56). The vaginal ring  (NuvaRing) is a contraceptive vaginal ring  that  releases 15 mg of ethinyl estradiol and  120 mg of the  progestin, etonogestrel. It is placed within the  vagina for three  weeks  and removed for one  week.  In one study, the incidence of irregular bleeding was  less compared with  an oral combination contraceptive (57). An injectable  combination of estradiol cypionate and  medroxyprogesterone acetate  (Lunelle)  has been devel- oped.  This is given as a monthly contraceptive injection. Contraceptive efficacy was shown to be comparable to a triphasic oral contraceptive containing ethinyl estra- diol and  norethindrone (Ortho  7/7/7) (58).

APPROACH TO HORMONAL THERAPY IN FEMALE ACNE

Hormonal therapy is an excellent  option for treatment of women whose acne is not responding to  conventional therapy. If there  are  signs  of hyperandrogenism, an endocrine evaluation is indicated, consisting of tests  such  as DHEAS,  total-  and free-testosterone, and  an  LH/FSH ratio.  Although hyperandrogenism is an  indi- cation  for  hormonal therapy, women with  normal serum androgen levels  also respond well to treatment. The mainstays of hormonal therapy include oral contra- ceptives and  spironolactone. Other   agents to  choose  from  include cyproterone acetate,  flutamide, and  glucocorticoids. Hormonal agents work  best  as part  of a combination  regimen  including  topical   retinoids or  topical   or  oral  antibiotics depending upon the severity of the acne. In some women, the additional of hormo- nal therapy has improved acne to the point  where subsequent treatment with  iso- tretinoin was no longer  necessary. As more is learned about  the hormones involved in acne,  their  source  of production and  the  mechanisms by which  they  influence sebaceous gland growth and  sebum production, new  opportunities will  arise  for the development of novel  therapies aimed at the hormonal aspects of acne.

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