PHARMACOLOGY

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PHARMACOLOGY

• Endocrine drugs

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OBJECTIVES

• Identify the classes of drugs that effect the
  endocrine system.
• Identify uses and varying actions of these drugs.
• Identify how these drugs are absorbed,
  distributed, metabolized, and excreted.
• Identify drug interactions and adverse reactions
  to these drugs.

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DRUGS AND THE ENDOCRINE SYSTEM

• Consists of glands and hormones.
• Regulates and integrates the body's metabolic
  activities and maintains homeostasis.
• Include the following drugs natural and
  synthetic hormones, hormonelike substances, and
  drugs that stimulate or suppress hormone
  secretion.

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DRUGS AND THE ENDOCRINE SYSTEM

• The following are categories of endocrine drugs
• Antidiabetic drugs and glucagon
• Thyroid and antithyroid drugs
• Pituitary drugs
• Estrogens

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ANTIDIABETIC DRUGS AND GLUCAGON

• Hypoglycemic drugs - lower blood glucose levels
  (insulin and oral antidiabetics).
• Hyperglycemic drugs - raise blood glucose levels
  (glucagon).
• Used to treat type I and type II diabetes
  mellitus.

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INSULIN

• Used for patients that need an external source of
  insulin to control blood glucose levels.
• Pharmacokinetics
• Administered subcutaneously (or IV) absorption
  depends on injection site distributed throughout
  the body metabolized primarily in the liver
  excreted in the feces and urine.

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INSULIN

• Pharmacodynamics
• An anabolic hormone that promotes
• Storage of glucose as glycogen.
• Increase in protein and fat synthesis.
• Slowing of the breakdown of glycogen, protein,
  and fat.
• Balancing of fluids and electrolytes.

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INSULIN

• Also can correct polyuria and polydipsia and
  facilitates the movement of potassium from the
  extracellular fluid into the cell.
• Pharmacotherapeutics
• Used to treat type I diabetes and type II
  diabetes when other methods have failed when
  blood glucose levels are elevated during periods
  of stress when oral agents are contraindicated.

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INSULIN

• Also used to treat diabetic ketoacidosis and
  hyperosmolar hyperglycemic nonketotic syndrome.
• Drug interactions
• Some drugs interact with insulin and other drugs
  directly affect blood glucose levels.
• Adverse reactions
• hypoglycemia

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ORAL ANTIDIABETIC DRUGS

• Types of oral antidiabetic drugs available
  include
• first generation sulfonylureas (clorpropamide -
  Diabenase)
• second generation sulfonylureas (glipizide -
  Glucotrol)
• nonsulfonylureas and thiazolidinedione
  antidiabetic drugs (pioglitazone - Actos)

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ORAL ANTIDIABETIC DRUGS

• a biguanide drug - metformin (Glucophage)
• an alpha-glucosidase inhibitor - acarbose
  (Precose)
• Pharmacokinetics
• Absorbed well from the GI tract distributed via
  the bloodstream throughout the body metabolized
  primarily in the liver excreted mostly in the
  urine.

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ORAL ANTIDIABETIC DRUGS

• Pharmacodynamics
• Probably stimulate the pancreatic beta cells to
  release insulin in a patient with a minimally
  functioning pancreas.Within a few weeks to a few
  months, pancreatic insulin drops to pretreatment
  levels but the blood glucose levels remain
  normal. This is most likely due to its actions
  outside of the pancreas.

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ORAL ANTIDIABETIC DRUGS

• PHARMACOTHERAPEUTICS
• Indicated for patients with type II diabetes if
  diet and exercise can't control blood glucose
  levels.
• May be used in combination with insulin for
  patients who don't respond to either drug alone.

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ORAL ANTIDIABETIC DRUGS

• Drug interactions
• hypo and hyperglycemia are the main risks when
  oral antidiabetic drugs interact with other
  drugs.
• Adverse reactions
• hypoglycemia

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GLUCAGON

• A hyperglycemic drug that raised blood glucose
  levels.
• Normally produced by the alpha cells of the
  islets of Langerhans in the pancreas.

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GLUCAGON

• Pharmacokinetics
• Administered parenterally absorbed rapidly
  distributed throughout the body effects occur
  primarily in the liver metabolized by the liver,
  kidneys, and plasma excreted by the liver and
  kidneys.

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GLUCAGON

• Pharmacodynamics
• Regulates the rate of glucose production through
  glycogenolysis (glycogen to glucose),
  gluconeogenesis (free fatty acids protein to
  glucose), and lipolysis (adipose tissue fatty
  acids to glucose).
• Pharmacotherapeutics
• Used for the emergency treatment of severe
  hypoglycemia.

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GLUCAGON

• Drug interactions
• interacts adversely only with oral anticoagulants
  increasing the tendency to bleed.
• Adverse reactions
• rare

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THYROID AND ANTITHYROID DRUGS

• Function to correct thyroid hormone deficiency
  (hypothyroidism) and thyroid hormone excess
  (hyperthyroidism).
• Natural or synthetic and may contain
  triiodothyronine (T3) and/or thyroxine (T4).
• Natural - animal - thyroid and thyroglobulin
• Synthetic - sodium salts of L-isomers of the
  hormones - levothyroxine (Synthroid Levoxyl),
  liothyronine sodium, and liotrix.

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THYROID AND ANTITHYROID DRUGS

• Pharmacokinetics
• Absorbed from the GI tract distributed in the
  plasma bound to serum proteins metabolized in
  the liver excreted unchanged in the feces.
• Pharmacodynamics
• The principal effect is an increased metabolic
  rate in body tissues.

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THYROID AND ANTITHYROID DRUGS

• Pharmacotherapeutics
• Act as replacement or substitute hormones in the
  following situations to treat hypothyroidism
  with antithyroid drugs to prevent goiter
  formation and hypothyroidism to differentiate
  between primary and secondary hypothyroidism
  during diagnostic testing to treat papillary or
  follicular thyroid carcinoma.

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THYROID AND ANTITHYROID DRUGS

• Levothyroxine is the drug of choice for thyroid
  hormone replacement and thyroid-stimulating
  hormone suppression therapy.
• Drug interactions
• Interact with several common medications.
• Adverse reactions
• Result from toxicity.

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ANTITHYROID DRUGS

• Also called thyroid antagonists.
• Used for patients with hyperthyroidism.
• Include the following drugs
• thionamides - propylthiouracil (Propyl-Thyracil)
  and methimazole (Tapazole)
• iodides - stable iodine and radioactive iodine

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ANTITHYROID DRUGS

• Pharmacokinetics
• Absorbed through the GI tract concentrated in
  the thyroid metabolized by conjugation
  (interchange of nuclear material) excreted in
  the urine.
• Pharmacodynamics
• Thionamides block iodines ability to combine
  with tyrosine preventing thyroid hormone
  synthesis.

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ANTITHYROID DRUGS

• The excess of stable iodine inhibits hormone
  synthesis through decreasing the formation and
  release of thyroid hormone.
• Radioactive iodine reduces hormone secretion by
  destroying thyroid tissue through acute radiation
  thyroiditis and chronic gradual thyroid atrophy.

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ANTITHYROID DRUGS

• Pharmacotherapeutics
• Used to treat hyperthyroidism especially in the
  form of Graves disease (autoimmune).
• Stable iodine is used to prepare the thyroid
  gland for surgical removal. Also used after
  radioactive iodine therapy.
• Propylthiouracil is usually used for rapid
  improvement of severe hyperthyroidism.

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ANTITHYROID DRUGS

• Methimazole is used for mild to moderate
  hyperthyroidism (administered once a day).
• Drug interactions
• May react synergistically with lithium causing
  hypothyroidism.
• Adverse reactions
• Granulocytopenia

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PITUITARY DRUGS

• Natural or synthetic hormones that mimic hormones
  produced by the pituitary gland.
• Consist of two groups
• Anterior pituitary drugs - control the function
  of other endocrine glands (thyroid, adrenals,
  ovaries, testes).
• Posterior pituitary drugs - used to regulate
  fluid volume and stimulate smooth muscle
  contraction in selected clinical situations.

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ANTERIOR PITUITARY DRUGS

• The hormones produced by the anterior pituitary
  gland regulate growth, development, and sexual
  characteristics by stimulating the actions of
  other endocrine glands.
• These drugs include adrenocorticotropics
  (corticotropin cosyntropin), somatrem (a growth
  hormone), gonadotropics, and thyrotropics.

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ANTERIOR PITUITARY DRUGS

• Pharmacokinetics
• Administered mostly by injection absorbed,
  distributed, and metabolized rapidly metabolized
  by the liver and kidneys excreted in the urine.
• Pharmacodynamics
• Exert a profound effect on the bodys growth and
  development.

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ANTERIOR PITUITARY DRUGS

• Pharmacotherapeutics
• Corticotropin (ACTH) and cosyntropin (Cortrosyn)
  are used diagnostically to differentiate between
  primary and secondary failure of the adrenal
  cortex.
• Corticotropin is also used to treat adrenal
  insufficiency.
• Somatrem (Protropin) is used to treat pituitary
  dwarfism.

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ANTERIOR PITUITARY DRUGS

• Drug interactions
• When corticotropins are taken with diuretics, an
  increased potassium loss may occur.
• Adverse reactions
• hypersensitivity
• Long term use can cause Cushings syndrome.

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POSTERIOR PITUITARY DRUGS

• These hormones are synthesized in the
  hypothalamus, stored in the posterior pituitary,
  and secreted into the blood.
• These drugs include
• Antidiuretic hormone (ADH) - vasopressin
  (Pitressin), desmopressin, and lypressin
• Oxytocic drugs - oxytocin (Pitocin)

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POSTERIOR PITUITARY DRUGS

• Pharmacokinetics
• Administered intranasally or parenterally
  absorbed, distributed, and metabolized rapidly.
• Pharmacodynamics
• Posterior pituitary hormones affect
• Smooth muscle contraction in the uterus, bladder,
  and GI tract.

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POSTERIOR PITUITARY DRUGS

• Fluid balance through kidney reabsorption of
  water.
• Blood pressure through stimulation of the
  arterial wall muscles.
• ADH promotes the kidneys reabsorption of water
  increases blood pressure.
• Oxytocin stimulates uterine contractions and
  lactation.

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POSTERIOR PITUITARY DRUGS

• Pharmacotherapeutics
• ADH is prescribed for hormone replacement therapy
  in patients with neurogenic diabetes insipidus.
• Desmopressin and lypressin are the drugs of
  choice for chronic ADH deficiency and are
  administered intranasally.
• Vasopressin elevates blood pressure for
  short-term.

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POSTERIOR PITUITARY DRUGS

• Oxytocics are used to induce labor, treat
  preeclampsia and eclampsia, control uterine
  bleeding, contract the uterus, and stimulate
  lactation.
• Drug interactions
• Can occur with various drugs.
• Adverse reactions
• Hypersensitivity

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ESTROGENS

• Mimic the physiologic effects of naturally
  occurring female sex hormones.
• Used to correct estrogen-deficient states and
  prevent pregnancy.
• Estrogens that treat endocrine disorders include
  
• Natural - estradiol and estrone
• Synthetic - diethylstilbestrol and quinestrol

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ESTROGENS

• Pharmacokinetics
• Absorbed well and distributed throughout the
  body metabolized in the liver excreted by the
  kidneys.
• Pharmacodynamics
• Believed to increase the synthesis of DNA, RNA,
  and protein in estrogen-responsive tissues in the
  female breast, urinary tract, and genital organs.

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ESTROGENS

• Pharmacotherapeutics
• Prescribed in the following situations hormone
  replacement therapy in post-menopausal women and
  in women with primary ovarian failure
  palliatively to treat advanced inoperable breast
  cancer in post-menopausal women and prostate
  cancer in men.

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ESTROGENS

• Drug interactions
• Few drug interactions.
• May decrease the effects of anticoagulants.
• Interfere with absorption of folic acid.
• Adverse reactions
• hypertension, thromboembolism, and
  thrombophlebitis