Transcript Drugs used in hypothyroidism

DRUGS USED IN
HYPOTHYROIDISM
by
Dr.Abdul latif Mahesar
Objectives




At the end of the lecture the students will be able
to :
Classify common drugs used for treatment of
hypothyroidism
Details the drugs regarding , mechanism of
action , pharmacological effects , clinical uses &
side effects
Recognize treatment of special cases of
hypothyroidism .
7
Hypothyroidism
Thyroid gland does not produce enough
hormones
 CAUSES
 Congenital ( cretinism , dwarfism)
 Autoimmune disorder ( Hashimotos
thyroiditis)
 Irradiation
 Surgical removal of thyroid gland
 Thyroid carcinoma

8
CAUSES
Congenital which results to ( cretinism ,
dwarfism)
 Autoimmune disorder ( Hashimotos
thyroiditis)
 Irradiation Of the gland
 Surgical removal of thyroid gland
 Thyroid carcinoma

9
HYPOTHYROIDISM

People who are most at risk include those over age 50
& mainly in females

Diagnosed by low plasma levels of T3 & T4
and high levels of TSH.

10
Manifestations of Hypothyroidism








Fatigue and lack of energy
weight gain
Dry and cold skin
Dry hairs
Constipation
Slowed thinking
Bradycardia
Heavy menses
11
12
13
14
15
16
Treatment

Replacement therapy with synthetic thyroid
hormone preparations
17
Thyroid preparations

LEVOTHYROXINE: (T4)

A synthetic form of the thyroxine (T4) , is the drug of
choice for replacement therapy .
Stable and has a long half life ( 7 days) .
Administered once daily.


Oral preparations available from 0.025 to 0.3 mg
tablets
Absorption is increased when hormone is given on empty
stomach


Parentral preparation 200-500µg .
18

In old patients and in patients with cardiac
problems , treatment is started with reduced
dosage.

Normal thyroid levels are restored within 2-3
weeks.

levothyroxine(T4) is given in a dose of 12.5 – 25
µg/day for two weeks and then increasing it after
every two weeks.

19
Clinical uses
Hypothyroidism, regardless of etiology
including :

Congenital

Autoimmune thyroiditis ( Hashimoto
thyroiditis)

Pregnancy

Thyroid carcinoma

20



ADVERSE EFFECTS OF OVER DOSES
CHILDREN : Restlessness, insomnia,
accelerated bone maturation.
ADULTS :
Tachycardia, palpitation, cardiac
arrhythmias, tremor , restlessness , heat
intolerance , headache, muscle pain
Change in appetite, diarrhea, weight loss
21
Adverse effects of under-dosing




Sluggishness
Mental dullness
Feeling cold
Muscle cramps
22
Liothyronine(T3)
More potent (3-4 times) and rapid action than
levothyroxine but has a short half life is not
recommended for routine replacement
therapy, it requires multiple daily doses.
 It should be avoided in cardiac patients.
 It is best used for short –term suppression of
TSH.
 Oral preparation available are 5-50µg tablets
 Parentral use 10µg/ml
23
MYXEDEMA COMA:

Life –threatening hypothyroidism

The treatment of choice is loading dose of levothyroxine
intravenously 300-400µg initially followed by 50µg daily.

I.V liothyronine for rapid response but it may provoke
cardiotoxicity

I.V hydrocortisone may be used in case of adrenal and
pituitary insufficiency.
24
HYPOTHROIDSM AND PREGNANCY.


In pregnant hypothyroid patient 20-30 %
increase in thyroxine is required because of
elevated maternal TBG(thyroxine binding
globulin) induced by estrogen and
because of early development of fetal brain
which depends on maternal thyroxine
25
Combination drugs
LIOTRIX
is a combination of synthetic T4 and
T3 in a ratio of 4:1 that attempt to mimic the
natural hormone secretions
Major limitation to this product are high cost
And lack of therapeutic rationale,because about
35% of T4 is peripherally converted to T3.

26