ORAL CONTRACEPTIVES
HOW ORAL CONTRACEPTIVES WORK
Combined pills (including phased pills)
increase the levels of oestrogen and
progesterone in the body, which
interferes with the production by the
pituitary gland of two
g o n a d o t r o p h i n
h o r m o n e s
called follicle-stimulating
hormone (FSH) and luteinizing
hormone (LH). This action in turn
prevents ovulation.
The progesterone-only pill (the
minipill) works partly by making the
mucus that lines the inside of the
cervix (neck of the uterus) so thick
that it is impenetrable to sperm.
____
P it u i t a r y g l a n d
G o n a d o t r o p h i n
h o r m o n e s
____
i n h i b i t e d
Hormonal effects
Each month the
pituitaryproduces
spurts of FSH and
LH, which act on the
ovaryto cause egg
ripening and
release. Combined
and phased pills
interfere with
natural hormone
production and thus
prevent ovulation.
R i p e n in g a n d
r e l e a s e o f e g g
p r e v e n t e d
Pill packaging
Most oral contraceptives come in packs, called
calendar packs, that clearly indicate which day
ofthe week each pill should be taken.
O v a r y
Effects on eggs
FSH normally brings about egg ripening and
LH
causes the egg’s release from the ovary;
combined pills prevent this.
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Combined pill
These pills contain an oestrogen and a
progestogen drug in fixed doses. A course
usually consists of one pill per day for 21 days,
M e n s t r u a t io n
followed byseven pill-free days, during which
bleeding may occur. A new course is then
started, whether or not bleeding has occurred.
ooooooooooooooooooooo
C h a n g e
C h a n g e
Phased pill
These are combined pills, containing both an
oestrogen and a progestogen drug. Unlike other
other combined pills, the doses change from
M e n s t r u a t io n
phase to phase (different timesduring the
month). A course lasts for 21 days followed either
byseven pill-free days or byseven inactive pills.
0000000000000000000000000000
Minipill
These pills contain only a progestogen drug in
a fixed dose. The pills are taken continuously:
one every daywith no pill-free days in between.
M e n s t r u a t io n
Bleeding usuallyoccurs during the last few days
of each cycle. The minipill has a slightly higher
failure rate than combined pills.
o p tim u m d o s e
T h e
a m o u n t
o f a n
a g e n t ,
s u c h
a s
a
d r u g , t h a t w i l l p r o d u c e a d e s i r e d e f f e c t
w i t h o u t c a u s i n g u n w a n t e d s i d e e f f e c t s .
o p to m e try
T h e p r a c t i c e o f a s s e s s i n g
v i s i o n
t o e s t a b -
l i s h w h e t h e r g l a s s e s
o r
c o n t a c t l e n s e s
a r e n e e d e d t o c o r r e c t a v i s u a l d e f e c t , a s
c a r r i e d o u t
b y a n o p t o m e t r i s t .
D i s o r -
d e r s o f t h e e y e m a y r e q u i r e t r e a t m e n t
b y a n
o p h t h a l m o l o g i s t .
( S e e a l s o
o p h -
t h a l m o l o g y
;
o p t i c i a n . )
o ra l
C o n c e r n i n g t h e
m o u t h .
o ra l c o n tra c e p tiv e s
COMMON DRUGS
oestrogens
• Ethinylestradiol •Mestranol
progestogens
•Desogestrel •Gestodene
• Levonorgestrel •Norethisterone
• Norgestimate
A g r o u p o f o r a l d r u g p r e p a r a t i o n s c o n -
t a i n i n g
o n e
o r
m o r e
s y n t h e t i c f e m a l e
s e x h o r m o n e s
t h a t a r e t a k e n b y w o m e n
i n a m o n t h l y c y c l e t o p r e v e n t p r e g n a n c y .
TYPES
“ T h e p i l l ” c o m m o n l y r e f e r s t o t h e c o m
-
b i n e d o r t h e p h a s e d p i l l ,
w h i c h b o t h
c o n t a i n a n
o e s t r o g e n d r u g
a n d a
p r o g e s t o -
g e n d r u g
,
a n d
t h e
m i n i p i l l
( o r
p r o g e s -
t e r o n e - o n l y p i l l ) , w h i c h c o n t a i n s o n l y a
p r o g e s t o g e n . T h e c o m
b i n e d p i l l i s t a k e n
f o r t h r e e w e e k s o u t o f e v e r y f o u r ; t h e
m i n i p i l l i s t a k e n c o n t i n u o u s l y .
EFFECTIVENESS
W
h e n o r a l c o n t r a c e p t i v e s a r e t a k e n c o r -
r e c t l y , t h e n u m b e r o f p r e g n a n c i e s a m o n g
w o m e n u s i n g t h e m f o r o n e y e a r i s l e s s
t h a n 1 p e r c e n t . H o w e v e r , a c t u a l f a i l u r e
r a t e s m a y b e u p t o f o u r t i m e s h i g h e r ,
p a r t i c u l a r l y f o r t h e m i n i p i l l , w h i c h h a s
t o b e t a k e n a t t h e s a m e t i m e e a c h d a y .
I f v o m i t i n g o r d i a r r h o e a o c c u r s a f t e r
a p i l l h a s b e e n t a k e n , t h e w o m a n s h o u l d
f o l l o w t h e
d r u g m a n u f a c t u r e r ’s a d v i c e
f o r a m i s s e d p i l l . I f a w o m a n t a k i n g o r a l
c o n t r a c e p t i v e s h a s m i s s e d t w o c o n s e c u -
t i v e m e n s t r u a l p e r i o d s , s h e s h o u l d h a v e
a
p r e g n a n c y t e s t
.
HOW THEY WORK
C o m b i n e d
a n d
p h a s e d
p i l l s
i n c r e a s e
o e s t r o g e n a n d p r o g e s t e r o n e l e v e l s . T h i s
i n t e r f e r e s w i t h t h e p r o d u c t i o n o f t w o
h o r m o n e s ,
l u t e i n i z i n g h o r m o n e
( L H ) a n d
f o l l i c l e - s t i m u l a t i n g h o r m o n e
( F S H ) , w h i c h
i n t u r n p r e v e n t s o v u l a t i o n . T h e m i n i p i l l
w o r k s p a r t l y b y m a k i n g t h e m u c u s l i n -
i n g o f t h e
c e r v i x
( t h e n e c k o f t h e w o m b )
t o o t h i c k t o b e p e n e t r a t e d b y
s p e r m
.
ADVANTAGES
O e s t r o g e n - c o n t a i n i n g p i l l s c a n h e l p p r o -
t e c t a g a i n s t u t e r i n e a n d o v a r i a n c a n c e r ,
o v a r i a n c y s t s , e n d o m e t r i o s i s ( i n w h i c h
f r a g m e n t s o f u t e r i n e l i n i n g a r e d i s p e r s e d ,
u s u a l l y a r o u n d t h e p e l v i c c a v i t y ) . T h e y
a l s o
t e n d
t o
m a k e
m e n s t r u a l
p e r i o d s
r e g u l a r , l i g h t e r , a n d r e l a t i v e l y p a i n - f r e e .
POSSIBLE ADVERSE EFFECTS
P o s s i b l e s i d e
e f f e c t s o f o e s t r o g e n - c o n -
t a i n i n g ( c o m b i n e d ) p i l l s i n c l u d e n a u s e a ,
w e i g h t g a i n , d e p r e s s i o n , b r e a s t t e n d e r -
n e s s ,
i n c r e a s e d
a p p e t i t e ,
r e d u c e d
s e x
d r i v e ,
l e g
c r a m p s ,
a b d o m i n a l
c r a m p s ,
h e a d a c h e s , a n d d i z z i n e s s . T h e y c a n a l s o
c a u s e o c c a s i o n a l s p o t t i n g
( s l i g h t b l o o d
O
567
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