The effect of triphasic oral contraceptives on plasma lipids and lipoproteins

Effects of oral contraceptives on metabolic parameters in adult premenopausal women: a meta-analysis

OBJECTIVE

To estimate the effect of oral contraceptives (OC) containing different progestins on parameters of lipid and carbohydrate metabolism through a systematic review and meta-analysis.

PATIENTS AND METHODS

Premenopausal women aged 18 or older, who received oral contraceptives containing chlormadinone, cyproterone, drospirenone, levonorgestrel, desogestrel, dienogest, gestodene or norgestimate, for at least 3 months. Outcome variables were changes in plasma lipids, BMI, insulin resistance and plasma glucose. We searched MEDLINE and EMBASE for randomized trials and estimated the pooled within-group change in each outcome variable using a random-effects model. We performed subgroup analyses by study duration (<12 months vs ≥12 months) and polycystic ovary syndrome (PCOS) status.

RESULTS

Eighty-two clinical trials fulfilled the inclusion criteria. All progestins (except dienogest) increased plasma TG, ranging from 12.1 mg/dL for levonorgestrel (P < 0.001) to 35.1 mg/dL for chlormadinone (P < 0.001). Most progestins also increased HDLc, with the largest effect observed for chlormadinone (+9.6 mg/dL, P < 0.001) and drospirenone (+7.4 mg/dL, P < 0.001). Meanwhile, levonorgestrel decreased HDLc by 4.4 mg/dL (P < 0.001). Levonorgestrel (+6.8 mg/dL, P < 0.001) and norgestimate (+11.5 mg/dL, P = 0.003) increased LDLc, while dienogest decreased it (-7.7 mg/dL, P = 0.04). Cyproterone slightly reduced plasma glucose. None of the progestins affected BMI or HOMA-IR. Similar results were observed in subgroups defined by PCOS or study duration.

CONCLUSION

Most progestins increase both TG and HDLc, their effect on LDLc varies widely. OC have minor or no effects on BMI, HOMA-IR and glycemia. The antiandrogen progestins dienogest and cyproterone displayed the most favorable metabolic profile, while levonorgestrel displayed the least favorable.

Oral contraceptives and the management of hyperandrogenism-polycystic ovary syndrome in adolescents

Appropriate management of polycystic ovary syndrome in adolescents depends on recognizing the syndrome, which can have a variety of presenting complaints and must be differentiated from other causes of hyperandrogenism, as well as not dismissed as "normal adolescence." Oral contraceptives have long been considered the first line of treatment by obstetrician/gynecologists and have many advantages in treating the aspects of PCOS that are most bothersome to teens. Because of the potential risk for cardiovascular disease, early diagnosis and management may be helpful in minimizing the risk of the early metabolic correlates of adult disease.

Triphasic oral contraceptives: review and comparison of various regimens

OBJECTIVE

To review and compare the risk-benefit profile of triphasic oral contraceptives with that of low-dose monophasic oral contraceptives.

DESIGN

Literature on currently marketed triphasics and monophasics.

PATIENT(S)

Healthy women of reproductive age.

MAIN OUTCOME MEASURE(S)

Comparison of the rationale for development, composition, mechanism, efficacy, menstrual cycle control, side effects, health benefits, and risk-benefit profile.

RESULT(S)

All triphasics contain ethinyl estradiol (0.025-0.040 mg/d) and one of several progestins in doses (0.05-1.0 mg/d) related to their relative potencies, which are substantially lower overall (total dose) than those in monophasics. The triphasics are highly efficacious. In general, menstrual cycle control and side effects are similar in both types, but triphasics containing the newer progestins (desogestrel, gestodene, and norgestimate) have better cycle control and a reduced incidence of androgenic side effects compared with those with norethindrone or levonorgestrel. Both triphasics and monophasics have minimal effects on carbohydrate and lipid metabolism and hemostasis parameters, and therefore comparable low risks of coronary heart disease. The health benefits of triphasics and monophasics are similar and include decreased incidence of unwanted and ectopic pregnancies, ovarian cysts, endometrial and ovarian cancers, benign breast disease, and acute pelvic inflammatory disease; less menstrual blood loss and iron deficiency anemia; and lower frequency of irregular bleeding and menorrhagia.

CONCLUSION(S)

The risk-benefit profiles of both triphasics and monophasics are favorable and similar.

Comparison of the lipoprotein, carbohydrate, and hemostatic effects of phasic oral contraceptives containing desogestrel or levonorgestrel

Desogestrel (DSG) is a less-androgenic progestogen than levonorgestrel (LNG). This difference in androgenicity may be responsible for observed differences in metabolic effects between oral contraceptive (OC) formulations containing almost equivalent estrogen doses but with either DSG or LNG as a progestogen. To test the hypothesis, a prospective 9-month randomized comparison of plasma lipids, glucose, insulin, hemostasis, and sex hormone binding globulin (SHBG) was conducted in 66 healthy women using phasic formulations of OCs containing either DSG (DSG-OC) or LNG (LNG-OC). The study results showed that SHBG increased 3-fold with DSG-OC and 2-fold with LNG-OC. DSG-OC increased HDL-C, HDL(2)-C and HDL(3)-C; LDL-C decreased transiently. LNG-OC decreased HDL(2)-C and increased HDL(3)-C; HDL-C was unchanged and LDL-C decreased transiently. Both formulations increased VLDL-C and triglycerides, more with DSG-OC, but apolipoprotein B levels increased equally. Apo A-I and A-II increased more with DSG-OC than with LNG-OC. Neither formulation altered Lp(a) or fasting glucose and insulin levels. Postprandially, both formulations decreased glucose and increased insulin responses, but to an equivalent degree. Both OCs slightly enhanced procoagulant and profibrinolytic parameters to the same extent except for internally compensating decreases in Factor V and protein S with DSG-OC. In summary, at almost equivalent estrogen doses, a phasic OC containing DSG compared with LNG has a less androgenic effect on lipoproteins and SHBG, similar effects on hemostatic parameters with lower protein S and factor V activity and equivalent effects on carbohydrate metabolism. The lipoprotein, SHBG, and protein S and factor V differences are likely due to the lesser androgenicity of DSG allowing for a greater expression of the dose of estrogen.

Update on androgenicity

The development of a new generation of progestins deemed less androgenic than their earlier counterparts has led to a number of misconceptions regarding their possible benefits in combination oral contraceptives. All combination oral contraceptives are beneficial for treating such androgenic conditions as acne and hirsutism. The only expressed androgenic effect of some first- and second-generation combined oral contraceptives are changes in plasma lipid and lipoprotein levels. However, the overall effect of today's low-dose oral contraceptives is largely lipid neutral, and human and monkey studies have shown that oral contraceptive use is associated with reduced, not increased, atherosclerosis rates. Myocardial infarction rates are not increased among oral contraceptive users, except among those who are heavy smokers.

The role of triphasic levonorgestrel in oral contraception: a review of metabolic and hemostatic effects

Epidemiological studies suggesting a possible association between the use of combined oral contraceptives and an increased risk of cardiovascular disease have led to extensive investigations into the effect of oral contraceptives on lipid and carbohydrate metabolism, and on hemostasis. Since this association was originally suggested, the steroid dose in oral contraceptives has been significantly reduced and new progestogens have been developed. Also, triphasic formulations have been introduced which offer a well-balanced estrogen/progestogen ratio, allowing a further reduction in the progestogen dose per cycle, and thus helping to minimize unwanted metabolic and hemostatic effects. The metabolic interactions of triphasic levonorgestrel, the first triphasic formulation to be introduced, have received particular attention. Lipid metabolism appears to be largely unaffected by triphasic levonorgestrel, most studies reporting no significant change in high- (HDL-C) or low-density lipoprotein-cholesterol (LDL-C) levels. Several studies have reported a decrease in the lipoprotein subfraction HDL2-C levels, but in most cases measurements of the LDL-C/HDL-C and apolipoprotein A-1/B ratios reveal no clinically significant effects. Concerning lipids, most studies suggest that triphasic levonorgestrel has less metabolic impact than the monophasic formulation. In common with all currently available oral contraceptives, triphasic levonorgestrel appears to have some effect on carbohydrate metabolism. The study results vary, however; some investigators have found an impairment of glucose tolerance, whereas others have not detected any significant effect. Compared with lipid and carbohydrate metabolism, fewer studies have investigated the effect of triphasic levonorgestrel on hemostasis. In common with all estrogen-containing oral contraceptives, levonorgestrel appears to stimulate some procoagulant activity, elevating the levels of factors VII and X, and fibrinogen. However, the effect of triphasic levonorgestrel appears to be balanced, with most studies reporting a corresponding increase in anti-coagulant-fibrinolytic activity. Although most of the studies reviewed here reported some statistically significant metabolic interactions, many authors comment that the changes are probably not clinically relevant in terms of an altered risk of cardiovascular disease. The true risk of vascular disease associated with modern low-dose oral contraceptives remains to be confirmed when sufficient epidemiological data eventually become available.

The androgenicity of progestins

All steroid hormones are structurally similar, but relatively minor differences cause profound alterations in biochemical activity. The 21-carbon series (pregnane nucleus) includes the corticoids and the true progestins (e.g., medroxyprogesterone acetate). The 19-carbon series (androstane nucleus) includes all the androgens, among them the progestins used in most oral and parenteral contraceptives. The removal of carbon 19 from testosterone changes the major hormonal effect from androgenic to progestogenic, but these "19-nor" steroids retain varying degrees of androgenic activity. (They can also have limited estrogenic activity, but this is insignificant at the low doses used for contraception.) Some of the 19-nortestosterone progestins are metabolized to other compounds (e.g., norethynodrel, ethynodiol diacetate, and lynestrenol to norethindrone), and some (levonorgestrel, desogestrel) are active unchanged. The lingering androgenic effects of 19-nor progestins are dose-related, opposed by estrogen, and are manifested metabolically (e.g., glucose tolerance, lipoprotein synthesis) and symptomatically (e.g., acne, weight gain). The effect of 19-nortestosterones on lipoproteins prompted the development of less androgenic compounds, but the obvious benefit of the new progestins (desogestrel, gestodene, norgestimate) is a reduction in the symptoms associated with the androgenicity of the older compounds. Mitigation of androgenic effects on lipoprotein and carbohydrate metabolism could have long-term benefits, especially for women who are at risk of arteriosclerotic vascular disease; however, these effects remain to be epidemiologically demonstrated.

Efficacy and safety of a monophasic and a triphasic oral contraceptive containing norgestimate

Both monophasic and triphasic formulations of ethinyl estradiol plus norgestimate, a progestin with marked progesterone-receptor affinity and minimal androgen-receptor affinity, have been evaluated in numerous clinical studies designed to determine if norgestimate's receptor-binding profile provides enhanced safety without a reduction in efficacy. To date clinical trials have shown that both formulations of ethinyl estradiol/norgestimate offer contraceptive efficacy equivalent to that of other oral contraceptives. Monophasic ethinyl estradiol/norgestimate was associated with an incidence of breakthrough bleeding and spotting similar to that of monophasic ethinyl estradiol/norgestrel and an incidence of amenorrhea less than that of ethinyl estradiol/norgestrel. Cycle control with triphasic ethinyl estradiol/norgestimate was similar to that with monophasic ethinyl estradiol/norgestimate. Weight gain and elevated blood pressure were insignificant in clinical trials with both fixed-dose and phasic ethinyl estradiol/norgestimate formulations. Perhaps of greatest importance, both monophasic and triphasic ethinyl estradiol/norgestimate formulations consistently showed favorable impact on metabolic parameters, including elevations in serum high-density lipoprotein cholesterol, and reductions in the low-density lipoprotein/high-density lipoprotein ratio, the parameter considered most sensitive for atherosclerotic risk. Both monophasic and triphasic ethinyl estradiol/norgestimate formulations were associated with minimal and clinically neutral effects on carbohydrate metabolism.

Prospective evaluation of insulin resistance and lipid metabolism in women receiving oral contraceptives

OBJECTIVES

It has been suggested that normal women receiving oral contraceptives (OC) may develop a series of metabolic side-effects which relate to the risk of cardiovascular disease. These metabolic disturbances include changes in glucose and insulin metabolism, raised serum lipid and lipoprotein concentrations and elevated blood pressure. All these changes indicate that OC might cause insulin resistance. We have prospectively examined the effect of OC on insulin resistance and lipid metabolism including Lp(a) values.

PATIENTS

The study group comprised 13 normally menstruating Chinese women.

DESIGN

The study subjects were given a combined triphasic oral contraceptive which was administered on a 21-day on, 7-day off medication cyclic regimen, the first pill being administered on day 5 from the beginning of menses. The metabolic investigations were carried out during luteal phase before OC and again the third week of the third month of OC administration.

MEASUREMENTS

Metabolic evaluation including insulin secretion and insulin-mediated glucose uptake were evaluated by oral glucose tolerance test and the modification of insulin suppression test. Fasting triglyceride, cholesterol, HDL-cholesterol and Lp(a) concentrations were also measured.

RESULTS

The plasma glucose and insulin responses during a 75-g oral glucose challenge increased significantly (P < 0.05 and P < 0.03, respectively). The steady-state plasma glucose (SSPG) concentrations achieved during constant infusion of glucose, insulin and somatostatin increased significantly after 3 cycles of OC administration (glucose 7.5 +/- 0.8 vs 12.4 +/- 0.7 mmol/l, P < 0.001) while the steady-state plasma insulin (SSPI) concentrations were relatively similar (410 +/- 14 vs 391 +/- 7 pmol/l, NS). Plasma triglyceride levels increased significantly (0.81 +/- 0.12 vs 1.09 +/- 0.19 mmol/l, P < 0.03) following OC administration. Fasting plasma cholesterol, HDL cholesterol and calculated LDL cholesterol concentrations did not change as compared with baseline values, nor did the ratio of total cholesterol to HDL cholesterol. The Lp(a) concentrations did not change during the administration of OC (81 +/- 25 vs 71 +/- 21 mg/l, NS).

CONCLUSIONS

These data indicated that intake of OC for 3 cycles induced glucose intolerance, hyperinsulinaemia and insulin resistance in normal menstruating Chinese women. These changes occurred in association with elevated plasma triglyceride concentrations and no alteration in Lp(a) or other lipid values.

The metabolic impact of oral contraceptives

The hormonal components of oral contraceptives exert major effects on plasma lipoprotein metabolism. Estrogens may increase production of plasma triglycerides, leading to increased levels of very low-density lipoproteins, but they may also reduce levels of cholesterol-enriched and potentially atherogenic intermediate- and low-density lipoproteins. Furthermore, estrogens increase levels of high-density lipoproteins (HDLs), particularly the HDL2 subspecies, an effect linked to reduced mortality rates from cardiovascular disease in postmenopausal women receiving hormone replacement therapy. All combination oral contraceptives in use in the United States tend to raise levels of plasma triglycerides, low-density lipoprotein, and HDL3 to varying degrees. In contrast, changes in HDL and HDL2 reflect the combined effects of estrogen dose and relative androgenicity of the progestin component. Although in general, the lipoprotein changes are greater in magnitude with higher dose oral contraceptive preparations, they can be significant in lower dose preparations as well. Oral contraceptives also affect carbohydrate metabolism, primarily through the activity of progestin. Studies have demonstrated insulin resistance, rises in plasma insulin, and relative glucose intolerance by means of curve analysis of glucose tolerance tests. These effects are far less pronounced with lower dose preparations and with formulations using the newer progestins.

The safety of oral contraceptives: epidemiologic insights from the first 30 years

Because oral contraceptives are used by tens of millions of healthy women, their safety for short-term and long-term use is an important issue that has been examined in a large number of epidemiologic studies. These studies have become more rigorous and have increased in size and analytic sophistication over the years. Although breast cancer remains the most important safety concern, the bulk of recent data suggests that oral contraceptives have no overall impact on a woman's risk of developing this disease. The results are less clear on the risk of cervical cancer and its precursors because of methodologic problems. However, the newer oral contraceptive formulations no longer appear to be associated with an increased risk of myocardial infarction or stroke.

Cyclic fluctuations in human serum lipid and apolipoprotein levels during the normal menstrual cycle: comparison with changes occurring during oral contraceptive therapy

The influence of menstrual cycle phases and hormonal contraception on serum lipid and apolipoprotein (apo) levels was investigated in a group of normally menstruating young women. The study period covered a normal menstrual cycle (pretherapy), the fourth cycle of treatment with a triphasic oral contraceptive (OC) preparation, and the cycle immediately following interruption of therapy (cycle 5, posttherapy). Cycle phases were defined on the basis of serum hormone levels and basal body temperature determinations. Significant differences in cholesterol (free and esterified) levels were observed during the menstrual phase of both the normal menstrual cycle (lower) and the OC cycle (higher), when compared with the other phases. Triglycerides, which were higher under OCs, fluctuated similarly throughout the two cycles, but phase differences did not reach statistical significance. Apo AI and apo B were both higher under OCs, and apo B followed a trend similar to cholesterol during the two cycles. During the first month after discontinuation of OCs, cholesterol levels returned progressively to baseline values, while triglycerides were only partially decreased. We conclude that cyclic fluctuations in lipid levels do occur under the influence of both endogenous and exogenous sex hormones.