Drugs for Thyroid and Upper Gastrointestinal Disorders

T3

TRH from hypothalamus ----> TSH from anterior pituitary -------> T3 & T4 from thyroid ------> inhibit TSH from anterior pituitary

Low T3 or T4 increases TSH, high T3 or T4 lowers TSH

Myxedema in adults

Cretinism in children

Goiter;  puffy, expressionless face; cold/dry skin; brittle hair; hair loss from scalp & outer ½ of eyebrows; fatigue; irritability; depression; lack of concentration; cold  intolerance; constipation; heavy menses; increased cholesterol

Permanent neuropsychological deficits, lower IQ, need replacement early in pregnancy

Mental retardation, large tongue, pot belly, dwarfish stature, derangement of growth - nerves, muscles, bone, teeth

One month

Without food

TSH decreases to  normal levels

Tachycardia, angina, tremor, nervousness, insomnia, hyperthermia, heat intolerance, sweating

Colestyramine (Questran), colestipol (Colestid), sucralfate (Carafate), calcium supplements, aluminum –containing antacids, iron supplements. 

1-2 hours.

Levothyroxine increases the degradation of Vitamin K-dependent clotting factors and may increase chance of bleeding.  May need to decrease dose of warfarin.

Levothyroxine increases the  body’s response to epinephrine, norepinephrine, and dopamine.

Rapid onset of action in myxedema coma.

Life-long replacement;  monitor for S&S of hypothyroidism & hyperthyroidism; hold levothyroxine if pulse >100/min & call primary care provider; monitor TSH, T3 & T; minimize adverse drug interactions

Severe tachycardia, heart failure, hyperthermia, profound weakness, coma.

Thyroid-stimulating immunoglobulins (TSI)

Rapid, strong heartbeat; rapid thoughts & speech; trouble concentrating; tremor; insomnia; weakened muscles; increased body temperature; warm, moist skin; increased appetite with weight loss; diarrhea; exophthalmos 

Decreased TSH

Inhibits thyroid hormone synthesis by inhibiting peroxidase.  Suppresses conversion of T4 to T3 in the periphery.

Agranulocytosis – may see sore throat or fever

Hypothyroidism

Inhibits thyroid hormone synthesis but does not block T4 or T3 in the periphery.

Hypothyroidism

Inhibits synthesis and release of thyroid hormones.

Brassy taste, burning of mouth, sore gums & teeth, may get severe abdominal pain

Hold if >100/min

Mucus – forms a barrier to protect underlying cells from gastric acid and pepsin.

Bicarbonate – neutralizes any acid which penetrates the mucus.

Blood flow – maintains integrity or health of the mucosa

Prostaglandins – Stimulates mucus and bicarbonate, vasodilates blood vessels, suppresses gastric secretion

Heliobacter pylori (H. pylori) – gram-negative bacillus which lives between the mucus layer and the mucosa.  Produces CO₂ and ammonia from urea which damages the mucosa.

NSAIDs – decreases the production of prostaglandins which decreases blood flow, decreases bicarbonate and mucus secretion, and increases gastric acid.

Gastric Acid – injures cells of the mucosa and activates pepsin.

Pepsin – breaks down protein of the gut wall.

Binds gastric acid and forms a neutral salt, inactivates pepsin if pH > 5, and stimulates prostaglandins.

1 and 3 hrs after meals and at bedtime, 1 hour before another drug, or every 2 hours if not eating

Aluminum hydroxide and sodium bicarbonate – heart failure, magnesium hydroxide – CNS toxicity in renal patients

Block H₂ receptors on parietal cells which suppress gastric acid secretion and decrease the hydrogen ion concentration in gastric acid.

May be taken without regard to meals, except take Tagamet with food

cimetidine (Tagamet)

Decreased gastric acid production

Before a meal – Nexium (1 hr), Prilosec, and Prevacid; doesn’t matter for the others

Stimulates uterine contractions.

Polymerization and cross-linking occurs when the pH is < 4.  It adheres to the crater for 6 hours.  Give 1 g before meals and bedtime or 2 g BID

1 hour between an antacid and sucralfate.

2 hours between drugs and sucralfate.

2-3 antibiotics with a proton pump inhibitor or histamine-2 receptor antagonist

Disrupts the cell wall of H. pylori, inhibits urease, and keeps H. pylori from adhering to the mucosa.  Black tongue and stools.

pH 5, > pH 6-7

5-6 small meals per day.  Bland food does not promote healing. Caffeine may not interfere with healing.

Black, tarry stools and coffee-ground vomitus.