suppression of the midcycle lh surge by a low-dose mestranol-lynestrenol oral combination

SUPPRESSION OF THE MIDCYCLE LH SURGE BY A LOW-DOSE MESTRANOL-LYNESTRENOL ORAL COMBINATION

K. Thomas, M.D. J. Ferin, M.D.

Physiology of Human Reproduction Research Unit Department of Obstretrics and Gynecology

University Hospital B - 3000 Louvain, Belgium

ABSTRACT

In a group of nine ovulating women receiving a low-dose mestranol-lynestrenol combination, the daily fluctuations of plasma LH concentration were measured by radioimmunoassey. In each woman a pre-treatment control cycle was investigated basing the occurrence of ovulation on the biphasic nature of the basal body temperature, the typical midcycle LH surge and the urinary pregnanediol excretion.

The daily administration of 0.040 mg mestranol- 1.0 mg lynestrenol produced in all volunteers a complete suppression of the midcycle LH surge. In half of the cases the basal LH pattern showed unstable and slightly elevated levels. Administration of 0.040 mg mestranol alone produced a strong stimulating effect on LH secretion. On the other hand, administration of 1.0 mg lynestrenol alone produced the suppression of the LH discharge without changing the basal values.

Research supported by the Ford Foundation, Grant no. 660 - 0425

Accepted for publication May 8, 1972

JULY 1972 VOL. 6 NO. ' I 1

CONTRACEPTION

INTRODUCTION

The contraceptive effect of estro-progestational combinations is attributed mainly to the inhibition of hypophyseal secretion of luteinizing and follicle-stimulating hormo- nes. It is at any rate one of the contraceptive mechanisms of lynestrenol and mestranol combinations used in the following doses: 0.150 mg of mestranol and 5.0 mg of lynestrenol (1, 2) 0.075 mg of mestranol and 2.5 mg of lynestrenol (2, 3, 4) 0.100 mg of mestranol and 0.5 mg of lynestrenol (5).

Following the discovery of a positive correlation between the dose of estrogen and the risk of thrombo-embolism (6) the general trend was to lower the daily dose of estrogen in the combined treatment. A new combination containing 0.040 mg of mestranol and 1.0 mg of lynestrenol was prepared. The question then arose as to whether the reduction of the dose of estrogen would not modify the major contraceptive mechanism of the combination.

The purpose of the present report is to offer an answer to this question, by studying the influence of the low-level mestranol-lynestrenol combination on plasma LH concentrations and comparing the results to those obtained by the administration of each of the two components separately.

MATERIAL AND METHODS

A group of nine healthy women, aged 20 -36 and demonstrating regular menstrual cycles was selected for this study. In each woman several consecutive cycles were explored, the first cycle being the control cycle. During this control cycle the occurrence of ovulation was based on (a) the biphasic pattern of the basal body temperature, (b) the typical midcycle plasma LH surge and (c) the levels of urinary pregnanediol. In the subjects LYV, HCH, MMA and CMR the control cycle did not immediately precede the treated cycle.

In four of the women the first cycle following the period of treatment was also explored for the basal body temperature and the midcycle LH surge. Details of these clinical and biological profiles are summarized in table I.

At the completion of the control cycle and beginning on the fifth day after the onset of the menses, two subjects (CPA and LFR) received a daily dose of 0.100 m~] mestranol and 1.0 mg lynestrenol for 21 days. The seven remaining subjects were given a daily dose of only 0.040 mg mestranol and 1.0 mg lynestrenol for 22 days beginning on day one of the cycle. Following a 6 day interval without medication three of these subjects (LYV, HCH, MMA) received the same dosage for an additional 22 days.

In an independent experiment one of the volunteers (CMY) received a daily dose of 0.040 mg mestranol for 31 days, starting on day one of the cycle. On day 32 of the cycle a dose of 0.080 mg and on day 33 a dose of 0.120 mg mestranol was given. On day 36 a dose of 10 mg progesterone was administered. This experiment is scheduled in Fig. 8. Another volunteer received a daily dose of 1.0 mg lynestrenol for 25 days beginning on day five of the cycle. This experiment is shown in Fig. 9.

The basal body temperature was recorded in all subjects throughout the whole study. All blood samples were collected in tubes containing powdered heparin at a concentration of 25 to 35 units of anticoagulant per ml of blood. Daily blood samples were obtained by venipuncture at 11.0 a.m. (-+ 1 hour) and immediately centrifuged. Plasma was frozen and stored at - 20 ° C prior to assay.

Plasma LH levels were measured using the dioxane radioimmunoassay method (7).

2 JULY 1972 VOL. 6 NO. I

CONTRACEPTION

T A B L E 1 - CLINICAL AND BIOLOGICAL DATA OF THE CONTROL CYCLES

Length Age of Cycles Volunteers [Years) (Days)

Control Cycle Before Treatment Control Cycle After Treatment

Plasma LH Pregnane- Plasma LH Basal Body Midcycle diol Basal Body Midcycle Length of

Temperature Surge mg/24 h Temperature Surge the Cycle

CPA (Fig.l) 21 30- 32 biphasic normal

LFR (Fig.2) 20 32- 35 biphasic normal

LYV (Fig.3) 27 29- 31 biphasic normal

HCH (Fig.4) 36 28- 30 biphasic normal

MMA (Fig.5) 24 28- 30 biphasic excessive

CMR (fig.6) 22 33- 36 biphasic normal

CMY (Fig.7) 26 29- 30 biphasic normal

HMI (no Fig.) 27 30 - 31 biphasic no control

RTH (no Fig.) 26 26- 32 biphasic normal

no data no data no data no data

no data no data no data no data

2.4 biphasic normal normal

2.9 no data no data no data


3.1 biphasic normal .normal

2.4 biphasic normal normal


no data biphasic no data normal

T A B L E I I - CLINICAL AND BIOLOGICAL DATA DURING THE TREATED CYCLE

Steroids Administered Plasma LH

Lynes- Basal Body Pregnane Break- With Volunteers Mestranol trenol Temperature Basal Midcycle diol Through Drawal

mg/day rag/day Levels Surge mg/24h Bleeding Bleeding

CPA (fig. 1 ) 0.100 1.0 hyperthermic stable suppressed no data 0 -H-

LFR (fig. 2) 0.100 1,0 hyperthermic stable suppressed no data 0 -H-

LYV (Fig. 3) 0.040 1,0 hyperthermic unstable suppressed 0.2 + - - 1 st cycle LYV (Fig. 3) 0.040 1,0 hyperthermic elevated suppressed 3.4 + + 2nd cycle unstable HCH (Fig. 4) 0.040 1.0 hyperthermic elevated suppressed 0.8 0 0 1 ste cycle unstable HCH (Fig. 4) 0.040 1.0 hyperthermic elevated suppressed 0.5 0 0 2nd cycle unstable MMA (Fig. 5) 0.040 1.0 hyperthermic stable suppressed 0,8 0 4:- 1 ste cycle MMA (Fig. 5) 0.040 1.0 hyperthermic stable suppressed 0.3 + 0 2rid cycle CMR (Fig. 6) 0.040 1.0 hypertherrnic unstable suppressed 0.3 + -IF

CMY (Fig. 7) 0.040 1.0 hyperthermic stable suppressed 0.8 + -H-

HMI (no Fig,) 0.040 1.0 hyperthermic stable suppressed 0.3 0 -IF

RTH (no Fig.) 0.040 1.0 hyperthermic elevated suppressed 0.1 + + unstable

.1ULY 1972 VOL. 6 NO. 1 O=absent; + = m i l d ; ++=moderate,~

C O N T R A C E P T I O N

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6 J U L Y 1972 V O L . 6 N O . I

CONTRACEPTION

The specificity of the anti-HCG used in measuring LH has been previously been described by demonstrating its non-reactivity with other glycoproteinsincluding HFSH and HTSH (8). The standard used throughout this study was the 2nd I RP-HMG. Determinations were carried out i n triplicate and the mean value of LH was expressed as milli- international units (mlU) of equivalents of the 2nd IRP-HMG per ml of plasma. In order to eliminate interassay errors all samples from each volunteer were measured in the same assay set.

Urinary pregnanediol was determined by the method described by BONGIOVANNI and CLAYTON (9) and slightly modified. With this method the 24-hour pregnanediol excretion for a normal corpus luteum function varies between 1.5 and 5 mg. The 24-hour urine samples were collected on day 21 (+- 2 days) of the cycle.

RESULTS

a) Pre-treatment control cycles (Table I and Figs. 1 - 7)

All nine subjects demonstrated a thermal shift at midcycle followed by a luteal phase ranging from 11 to 15 days. In seven of the eight cycles, where LH levels were measured, a normal midcycle LH peak was found (mean peak value: 81 mlU/ml), whereas for the remaining volunteer MMA (Fig. 5) an excessive LH peak was observed. Beside the midcycle LH peak small LH elevations were observed, but not comparable to the normal midcycle LH surge. In the six subjects in whom the 24-hour pregnanediol excretion was determined, the values found around day 21 were compatible with a normal corpus luteum function. As judged by these criteria all control cycles were ovulatory.

b) Mestranol-lynestrenol treated cycles (Table II and Figs. 1 - 7)

In all treated cycles the steroid combination had a hyperthermic-monophasic effect on the basal body temperature.

The typical midcycle LH surge was suppressed in all 12 treated cycles. Neither during the first nor the second half of the treated cycle were discharges comparable to normal midcycle peaks observed.

In six of the 12 treated cycles the basal LH levels were unaffected by the treatment, when compared with the basal levels of the control cycles. In two cYcles (LYV, lste treated cycle, and CMR) the basal values were characterized by a marked instability and in four cycles (LYV 2nd treated cycle, HCH and RTH) this instability was combined with a slight elevation of the basal LH concentrations. The three volunteers (LYV, HCH, MMA) who received treatment during two consecutive periods, showed similar LH pattern during the first and second course of treatment. In none of the treated cycles was a defined depression of the basal LH concentrations observed. The LH patterns were influenced in the same manner if 0.100 mg or 0.040 mg mestranol was combined to 1.0 mg lynestrenol.

JULY 1972 VOL. 6 NO. 1 7


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In all treated cycles, in which pregnanediol excretion was measured, the amounts found during the second half of the treated cycles were below values characteristic for a luteal phase, except for one (LYV 2nd treated cycle). Mild break-through bleeding occurred during 6 of the 12 periods of treatment and withdrawal bleeding was absent in two subjects.

c) Post-treatment control cycles (Table I and Figs. 3, 6, 7)

In the four explored subjects the basal body temperatures were biphasic and the length of the cycle normal. The LH determination performed in three of these subjects revealed the re-appearance of the midcycle LH surge during the first post-treatment cycle.

d) The mestranol treated cycle (Fig. 8)

During the administration of a daily dose of 0.040 mg mestranol LH levels rose within 10 days up to 54 m lU/ml of plasma and persistently high LH concentrations were measured, which reached midcycle LH peak values (90 mlU/ml) with the-increasing mestranol dose. After the intra-muscular injection of 10 mg progesterone an additional rise was observed attaining levels of 121 mlU/ml of plasma. This completely disturbed LH secretion was immediately followed by an ovulatory cycle, where a normal midcycle LH surge was measured. During the treated cycle basal body temperature remained hypo- thermic-monophasic.

e) The lynestrenol treated cycle (Fig. 9)

During the daily administra'tion of 1.0 mg lynestrenol no midcycle LH discharge was observed and the basal LH levels were unaffected by the treatment. The basal body temperature had a hyperthermic- monophasic pattern.

DISCUSSION

There is no doubt that the low-dose combination of mestranol-lynestrenol investigated in the present study is equally as capable of suppressing the LH midcycle discharge as the high-dose combinations of the same compounds currently used for oral contraception.

Bearing in mind the prominent role attributed to the midcycle LH surge in the maturation of the ovocyte, ovulation and the subsequent formation of the corpus luteum, it is therefore probable that the preparation investigated will also possess a highly effective contraceptive quality.

However, the limited number of cases observed imposes some reservation, and a much larger number of observations would be necessary in order to form a definite opinion. It must be noted, furthermore, that only the first and second courses of treatment were investigated. Up til l now, however, no observation has been carried out that would prove any reduction with time in the contraceptive action of these combinations.

The fact that a urinary pregnanediol level corresponding to a post-ovulatory phase

JULY 1972 VOL. 6 NO. 1 9


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12 J U L Y 1972 VOL. 6 NO. 1

CONTRACEPTION

was found in one case probably does not diminish the contraceptive efficacy of the drug. Indeed, similar observations were made at the beginning of the era of oral contraception (10,11) with various combinations of proven contraceptive efficacy. It is possible that a short LH discharge occurred between two measurements made 24 hours apart, but carefully timed dissection of the normal midcycle LH discharge has demonstrated that it always lasted longer than 24 hours (12). Furthermore, a blood progesterone pattern compatible with a post-ovulatory phase, was observed without the midcycle discharge of LH during daily administration of 0.5 mg of chlormadinone acetate (13). What takes place in the ovary in such cases is not known.

In half of the treated cycles the basal LH levels were unstable and/or slightly elevated. Th.ese patterns are not usually observed during administrations of estro- progestational combinations (14,15) and even depression of LH concentrations to below normal follicular phase levels has been reported (16). Therefore it was of interest to explore the LH pattern during the administration of each of the two components separately.

With a daily dose of 1.0 mg of lynestrenol, complete inhibition of the midcycle LH discharge was observed. This is not surprising since even lower doses of lynestrenol are capable of producing identical results (17). Only at a dose-level of 0.100 mg per day is this effect no longer observed ( 14,15).

On the other hand, mestranol in a daily dose of 0.04 mg produced a strong stimulating effect on LH secretion. With the progressive increase of the dose of mestranol LH concentrations reached values identical with midcycle LH peaks. An additional release of LH was observed following the administration of progesterone. Results suggesting a trigger effect of progesterone have already been described (14, 18).

It is now generally accepted that estrogens do have a trigger effect on the release of LH in woman (19). However, the conditions for and the development of this release are far from clear. Neither the dosage nor the duration of the treatment seem to play a decisive role. The stimulating effect on LH release of low-level estrogen doses observed in this study confirms earlier data (20,21). But higher dosage levels may also be effective in this respect (21,22). It must be noted, however, that starting estrogen treatment on day 1 of the cycle instead of day 5 seems to be more effective, in suppressing gonadotropin release (15,21). It is probable that the type of hypothalamo-hypophyseal response to estrogen administration is conditioned by the basal hormonal state of the subject. In the ovary, 0.150 mg of mestranol inhibits corpus luteum formation, whereas with 0.075 mg this inhibition is not always observed (23).

Finally, this study confirms earlier observations showing that the hypothalamo- hypophyseal axis quickly resumes its normal function after cessation of the therapy.

JULY 1972 VOL. 6 NO. 1 13

CONTRACEPTION

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14 J U L Y 1972 VOL. 6 NO. 1

CONTRACEPTION

REFERENCES

1. LAURITZEN, C., in Research on Steroids (C. Cassano, Editor) II Pensiero Scientifio, Roma, 1966, vol. 2, p. 421-430.

2. SCHMIDT-ELMENDORFF, H. and KOPERA, H. The effect of various antiovulatory compounds on the FSH, LH and "total gonadotrophin" excretion during the menstrual cycle. Excerpta Med, Internat Congr Series n ° 133 : 1049o1055 (1967).

3. KELLER, M. Hormonausscheidungen unter und nach Behandlung mit Lyndiol 2.5. Gynaecologia 163 : 187-198 (1967).

4. ACHTARI, H., LEMARCHAND-BERAUD, Th. and CURCHOD, A. Plasma LH and FSH concentrations in women during and after interruption of contraceptive treatment. Acta endocr (Kbh) suppl 155:169 (1971).

5. SCHMIDT-ELMENDORFF, H., KAISER, E. and KOPERA, H. The effect of 0.5 mg lynestrenol with and without 0.1 mg mestranol on the FSH, LH, oestrogen and pregnanediol excretion during the menstrual cycle. Acta endocr (Kbh) suppl 119: 152 (1967).

6. INMAN, W.H.W., VESSEY, M.P., WESTERHOLM, B. and ENGELUND, A. Thrombo-embolic disease and the steroidal content of oral contraceptives A report to the committee on safety of drugs. Brit Med J 2 : 203-209 (1970).

7. THOMAS, K. and FERIN, J. A new rapid radioimmunoassay for HCG (LH, ICSH) in plasma using dioxan. J Clin Endocr 28 : 1667-1670 (1968).

8. THOMAS, K., NASH, D. and FERIN, J. Chemical precipitation techniques for the radioimmunologic quantitation of gonadotrophins with special reference to the organic solvent dioxane. Acta endocr (Kbh) 63, suppl 142:279-299 (1969).

9. BONGIOVANNI, A.M. and CLAYTON, G.W. A simplified method for the routine determination of pregnanediol and pregnanefriol in urine. Bull Johns Hopkins Hosp 94 : 180-186 (1954).

10.

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GOLDZIEHER, J.W., MOSES, L.E. and ELLIS, L.T. Study of norethindrone in contraception. JAMA 180 : 359-361 (1962).

NEVINNY-STICKEL, J. Inhibition of ovulation determined by estimation of pregnanediol excretion. Int J Fertil 9 : 57-67 (1964).

12. THOMAS, K., WALCKIERS, R. and FERIN, J. Biphasic pattern of LH midcycle discharge. J. Clin Endocr 30 : 269-272 (1970).

13. JAFFE, R.B., MIDGLEY, A.R., GOEBELSMANN, U. and SNYDER, D.L. Regulation of human gonadotropins. IX. Effects of administration of low-dose chlormadinone acetate upon serum luteinizing hormone, follicle stimulating hormone, progesterone and urinary pregnanediol. Gynec Invest 1 : 169-178 (1970).

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CONTRACEPTION

14.

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FERIN, J. and THOMAS, K. Influence des progestatifs sur le LH plasmatique. Bull Acad Suisse Sc Med 25 : 287-295 (1969).

THOMAS, K., NASH, D. and FERIN, J., in Proceedings of the International Seminar on Maternal Mortality, Family Planning and Biology of Reproduction (B.N. Puran- dare and C.L. Jhaveri, Editors) Karnatak Orion Press, Bombay, 1969, p. 122-128.

ROSS, G.T., ODELL, W.D. and RAYFORD, P.L. Oral contraceptives and luteinizing hormone. Lancet 2 : 1255-1256 (1966).

THOMAS, K., PIZARRO, M. and FERIN, J. Effects of administration of low-dose lynestrenol on plasma LH and progesterone levels (unpublished data).

ODELL, W.D. and SWERDLOFF, R.S. Progestogen-induced luteinizing and follicle- stimulating hormone surge in postmenopausal women : a simulated ovulatory peak. Proc N A S 61 : 529-536 (1968).

VANDE WlELE, R.L., BOGUMIL, J., DYRENFURTH, I., FERIN, M., JEWELEWlCZ, R., WARREN, IVI., RIZKALLAH, T. and MIKHAIL, G.,Mechanisms regulating the menstrual cycle in women, Recent Progress in Hormone Research 26 : 63- 103 (1970).

JAFFE, R.B. and MIDGLEY, A.R., Jr. Current status of human gonadotropin radioimmunoassay. Obstet Gynec Survey 24 : 200-213 (1969).

STEVENS, V.C., GOLDZIEHER, J.W. and VORYS, N. Effect of mestranol and chlormadinone acetate on urinary excretion of FSH and LH. Amer J Obst Gynec 102 : 95-105 (1968).

YEN, S.S,C. and TSAI, C.C. The biphasic pattern in the feedback action of ethinyl- estradiol on the release of pituitary FSH and LH. J Clin Endocr 33 : 882-887 (1971).

BOTELLA-LLUSIA, J., in I ' lnhibition de I'Ovulation (A. Netter, Editor) Masson, Paris, 1970, p. 141-156.

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suppression of the midcycle lh surge by a low-dose mestranol-lynestrenol oral combination

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