Drugs

Question 1

thioamides

Answer 1

inhibit TPO enzymes; inhibits oxidation, organification and coupling

Question 2

Levothyroxine (Levothroid, synthroid)

Answer 2

T4 salt of natural L-isomer
absorbed well following oral admin with 1/2 life of 7days
DOC- hormone replacement therapy in hypothyroidism
caution should be taken when substituting generic for brand named due to the drugs narrow therapeutic index, shelf life instability, and product to product variations

Question 3

Liothyronine (cytomel)

Answer 3

T3 Salt
absorbed well after PO admin with 1/2 life of 1-2d
DIAGNOSTIC agent for suppression of TSH ; not recommended for replacement therapy due to short half life

Question 4

Liotrix (thyrolar)

Answer 4

salts of T4 and T3 in 4:1 ratio; expensive

Question 5

Antithyroid agents

Answer 5

drugs that interfere with biosynthesis of thyroid hormones, bock iodide uptake, or selectively destroy thyroid follicular cells

Question 6

Propylthiouracil (PTU)

Answer 6

INHIBITS synthesis of thyroid hormones by blocking iodine organification and coupling
absorbed well following oral administration, metabolized in the liver and excreted in the urine

only indicated for treatment of Graves disease in patients during first trimester of pregnancy (also DOC for thyroid storm)
higher risk of liver toxicity than methimazole

slow onset of action; used in conjunction with Beta adrenergic antagonists to control hyperthyroid symptoms and prevent thyroid storm

Question 7

methimazole (tapazole)

Answer 7

INHIBITS synthesis of thyroid hormones by blocking iodine organification and coupling
absorbed well following oral administration, metabolized in the liver and excreted in the urine

indicated for tx of all other patients with hyperthyroidism
slow onset of action; used in conjunction with Beta adrenergic antagonists to control hyperthyroid symptoms and prevent thyroid storm

Question 8

Potassiun Iodide solutions

Answer 8

block iodide uptake; paradoxically inhibits iodide trapping, T3 and T4 synthesis and release, and decrease the size and vascularity of the hyperactive thyroid gland

used in conjunction with PTU (antithyroid drugs) to prepare hyperthyrid patients for thyroidectomy
solutions contain 5% iodine and 10% potassium iodide (Lugol’s solution) are given orally at a dosage of 50-150 mg per day

Question 9

Radioactive Iodine (I-131)

Answer 9

rapidly and efficiently accumulated by the thyroid gland, incorporated into thyroglobulin and stored in the follicles (the destructive beta rays act to destroy follice cells with little or no damage to the surrounding tissue)
absorbed well following oral admin with 1/2 life of 8 days (used in conjunction with thyroid hormone replacement therapy)

Question 10

Perclorate and thiocyonate

Answer 10

inhibits trapping: specifically the sodium iodide symporter

Question 11

Iodine

Answer 11

inhibits thyroid hormone release

Question 12

octreotide

Answer 12

synthetic truncated analog of somatostatin that acts to inhibit somatotrophy GH secretion
somatostatin receptor agonist that suppresses GH secretion via a direct action on pituitary tumors

treatment for Acromegaly

Question 13

pegvisomant

Answer 13

genetically engineered analog of human GH that acts as a GH receptor antagonist to suppress GH-inuced IGF secretion by the liver
requires daily sc injections taken indefinitely
expensive
treatment for acromegaly

Question 14

recombinant human GH-somatotropin

Answer 14

GH supplement for GH deficiency that is expensive
also used for patient with short stature
treatment consists of 7-8 sc injections per week for years

Question 15

bromocriptine (parlodel) and cabergoline (Dostinex)

Answer 15

dopamine receptor agonist to inhibit prolactin secretion and shrink the size of prolactin secreting adenomas (cabergoline is more potent and causes less nausea)

Question 16

flutamide

Answer 16

androgen receptor agonist- competes for binding with testosterone and DHT
pro-drug converted to active 2-hydroxyflutamide
stimulates endogenous testosterone secretion due to loss of negative feedback on GnRH
used in conjunction with a GnRH analog to treat prostatic cancer

Question 17

Finasteride

Answer 17

5 alpha reductase inhibitor-blocks conversion of testosterone to DHT
used to treat BPH and male pattern baldness

Question 18

sildenafil (viagra)

Answer 18

tx of erectile dysfunction
potentiates parasymp responses to sexual arousal
selective phosphodiesterase 5 inhibit to maintain cGMP dilation of the corpus cavernosum
orally active drug with active metabolite
30 min onset
4 hour duration of action
hypotension an adverse side effect
approved for tx of pulmonary hypertension

Question 19

vardenafil (levitra)

Answer 19

phosphodiesterase inhibitor but more potent than sildenafil

Question 20

tadalafil (cialis)

Answer 20

equally as potent as vardenifil but delayed onset and longer duration of action

Question 21

testosterone cypionate

Answer 21

synthetic androgen used in testosterone replacement theraoy

Question 22

mifepristone

Answer 22

anti-progestin that competes with the natural ligand, progesterone for binding to the PR; can be medically to induce 1st trimester abortion

Question 23

tamoxifen

Answer 23

partial antagonist of the estrogen receptor, best known as an anti-estrogen that is used in tx of ER-positive breast tumors