Oral Contraceptives

ORAL CONTRACEPTIVES Presented by: Pauline Teo Pharmacy Department, Hospital Miri

8th July, 2009

OUTLINE         

Contraceptive methods Menstrual cycle Mechanisms of action Type of OCPs Non-contraception benefits of OCPs Adverse effects Contraindications Drug interactions Counseling

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CONTRACEPTION METHODS     

Oral contraceptives Hormonal methods Mechanical/Barrier methods Natural methods Sterilization Emergency contraception Oral contraceptives

Combined oral contraceptives (COC)

Progestin-only pills (mini-pill)

Emergency contraception

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THE MENSTRUAL CYCLE

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THE ESTROGENS Estrogens

Natural • estradiol • estrone • estriol

Semi-synthetic • ethinyl estradiol

Synthetic • mestranol

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THE PROGESTOGENS 

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Progesterone – most important natural progestogens Examples of Progestogen:  Medroxyprogesterone, Dyhydrogesterone, Gestodene, Levonorgestrel, Cyproterone acetate, Desogestrel, Drospirenone, Norethisterone, Norgestimate 6

ORAL CONTRACEPTIVES: Mechanisms of action 

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Estrogen  inhibit secretion of FSH & thus preventing the development of a dominant follicle Progestogen  suppress LH & thus prevent ovulation  cause atrophy of endometrium  alter fallopian tube secretion  thicken cervical mucus which interferes with sperm transport 7

MECHANISMS OF ACTION Suppress ovulation Reduce sperm transport in upper genital tract (fallopian tubes) Change endometrium making implantation less likely

Thicken cervical mucus (preventing sperm penetration)

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COMBINED ORAL CONTRACEPTIVES (COC)   

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Estrogen + Progestogen Estrogen content: 20-40 ug 21 days of active (hormone-containing) pills followed by either 7 days of placebo pills or instructions of not to take pills for 7 days Menstrual bleeding usually begins 1 to 4 days after cessation of a 21-day cycle of COCs or during placebo tablets of 28-day pack

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COC (con’t) COC

Monophasic

Biphasic

Triphasic

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COC (con’t) 

Monophasic: contain a fixed ratio of estrogen & progestin given daily for 21 days

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Eg:  Marvelon®, Regulon® (Desogestrel 150ug, EE 30ug)  Microgynon 30®, Nordette®, Rigevidon® (Levonogestrel 150ug, EE 30ug)  Diane 35®, Estelle-35® (Cryproterone acetate 2mg, EE 35ug)  Meliane® (Gestodene 75ug, EE 20ug)  Mercilon®, Novynette® (Desogestrel 150ug, EE 20ug)  Loette® (Levonogestrel 100ug, EE 20ug)  Gynera®, Minulet® (Gestodene 75ug, EE 30ug)  Yasmin® (Drospirenone 3mg, EE 30ug)

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COC (con’t) 

Biphasic: contain a fixed dose of estrogen (days 1-21) with a lower progestin dose on days 1 to 10 than on days 11 to 21  1st half: the progestin/estrogen ratio is lower to allow the endometrium to thicken as it normally does.  2nd half: the progestin/estrogen ratio is higher to allow normal shedding of the lining of the uterus to occur

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COC (con’t) 

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Triphasic: have constant or changing estrogen concentrations and varying progestin concentrations throughout the cycle Eg:  Trinordiol®  6 brown tabs (EE 30ug, Levonogestrel 50ug) + 5 white tabs (EE 40ug, Levonogestrel 75ug) + 10 yellow tabs (EE 30ug, Levonogestrel 125ug)

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PROGESTIN-ONLY PILLS   

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Contain no estrogen Given for 28 days continuously A good choice in lactating women  efficacy is increased as a result of the combined effect of prolactin-induced suppression of ovulation  does not adversely affect milk volume & infant growth Alternative for those who are unable to take estrogens Less effective than COC Eg: Noriday® (norethisterone 0.35mg)

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EMERGENCY CONTRACEPTION 

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Used only when there is an episode of unprotected sex or there is potential contraceptive failure Synonyms: “morning-after pill”, “post-coital contraception” Should be taken within 72 hours If vomiting occurs within 2 hours after drug intake, dose should be repeated 15

EMERGENCY CONTRACEPTION (con’t) 

Progestogen only emergency contraception (POEC)  0.75mg levonorgestrel (Madonna®, Postinor-2®)  2nd dose: 12 hours later (not >16 hours)  1.5mg levonorgestrel (Escapelle®)  s/e: nausea (20%), vomiting (5%) 16

NON-CONTRACEPTION BENEFITS OF OCPs         

Improves menstrual disorders ↓ in dysmenorrhea prevent ectopic pregnancy ↓ risk of pelvic infection ↓ in functional ovarian cysts ↓ risk of loss of bone density ↓ incidence of ovarian cancer ↓ incidence of endometrial cancer Improvement in acne & hirsutism

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ADVERSE EFFECTS          

Breakthrough bleeding/ spotting Amenorrhea Nausea, vomiting, anorexia Breast tenderness Headache Depression Weight gain Change in BP Acne Chloasma 18

CONTRAINDICATIONS           

Smokers aged ≥ 35 years Hypertension Myocardial infarct Stroke Thrombosis Severe migraine Poorly controlled diabetes Severe obesity Gall bladder disease or liver tumours Known or suspected pregnancy Unexplained vaginal bleeding 19

DRUG INTERACTIONS 

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↓ effectiveness of OCP  Rifampicin  Antifungal  Barbiturates  Phenytoin  Certain antibiotics  Activated charcoal  Laxatives  St John’s wort Requirement for oral antidiabetics & insulin can change The actions of TCAs, theophylline, diazepam are potentiated by OCP 20

COUNSELING     

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Daily, same time each day Take with food or immediately after food If you vomit within 4 hours of taking pill, repeat the dose Start 1st day of menstrual cycle  protection starts from the very 1st pill Start on other time in menstrual cycle  must use a different form of contraception for 7 days (COC) or 48 hours (POP) Do not protect against STDs (eg: HIV/AIDS) If you miss 2 or more menstrual periods, should check for pregnancy If you become sick and have severe diarrhea or vomiting for several days, you should use another method of contraception until you next period 21

IF COCs ARE MISSED  

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A pill is regarded as missed if it is >12hours late If you forget to take 1 pill, take it as soon as you remember, even if it means taking 2 pills on 1 day. Missed 2 or more pills Take a pill at once: - If 7 or more pills left, take the rest of the pills as usual - If < 7 pills left, take the rest of the pills as usual and omit the pill-free interval Additional contraceptive for the next 7 days 22

IF POPs ARE MISSED     

A pill is regarded as missed if it is >3 hours late The missed pill should be taken as soon as one remembers The next pill should be taken at the usual time Avoid sexual activity If sexual activity cannot be avoided, use additional contraception for 48 hours. 23

REFERENCES      

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Milton SW Lum 2003. Contraception. Malaysia: Kuala Lumpur Blackburn RD, Cunkelman JA & Zlidar VM 2000. Oral ContraceptivesAn Update. Population Reports: Series A, Number 9 Zlidar VM 2000. Helping Women Use the Pill. Population Reports: Series A, Number 10 MyHEALTH for life. Reproductive Health: Family Planning. Adapted from http://www.myhealth.gov.my British National Formulary (BNF), Issue 54, September 2007. RPS Publishing MedlinePlus Drug Information: Estrogen and Progestin (Oral Contraceptives). American Society of Health-System Pharmacists, Inc. Adapted from http://www.nlm.nih.gov/medlineplus/druginfo/ meds/a601050.html [27 April 2009] Roberts H 2008. Combined oral contraceptives: Issues for current users. BPJ:12:21-29.

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