Drugs affecting the endocrine system Flashcards
Hypo and Hyperthyroid agents: Thyroxine and thioureas (thioamides) for the treatment of thyroid dysfunction. Treatment of Type I and II Diabetes: Insulin and oral hypoglycaemics. Pharmacological actions of corticosteroids on humans. Pharmacological effects of glucocorticosteroids in the body and the adverse effects of long term use.
Drug therapy of hypothyroidism involves thyroid hormone replacement therapy which can be provided either by giving…..?
thyroxine (synthetic T4) or liothyronine (sodium salt of T3).
Indications: Thyroxine (Oroxine ®, Eutroxsig ®)?
Mechanism of action?
Hypothyroidism, goitre, replacement therapy after thyroid block in hyperthyroidism, thyroiditis and thyroid carcinoma.
metabolized to the biologically active form (T3), replacing lowered levels of endogenous thyroid hormone.
Thyroxine: Dosage and warnings….?
Because of the long-half life of thyroxine, doses should be titrated slowly (3 to 4 weeks) to maintenance (100 μg daily) or titre again slowly to 150 μg daily if required. Elderly and clients with ischaemic heart disease, lower start and maintenance doses. For all clients, monitor regularly (every 4-6 weeks, yearly cardiac check)
ADR usually minimal at appropriate doses but include insomnia, reduced bone mineral density (in pre-menopausal women 150 μg dose, effect is minimized)
Drug interactions include warfarin, cholestyramine,
Use with caution: e.g. Diabetes mellitus, Adrenocortical/pituitary
insufficiency, Cardiac disease.
Do not use if hypothyroidism has not been dignosed.
Hyperthyroidism… Drug therapies?
And Mechanism of action?
Carbimazole (Neo-Mercazole®) or Methimazole Propylthiouracil (PTU) Antithyroid effect (inhibition of iodination of tyrosine, some inhibition of thyroxine synthesis).
Adverse reactions to anti-hyperthyroid drugs?
Gastro-intestinal, headache, rashes, bone marrow depression, hematological disturbances. Symptoms of hypothyroidism in overdose.
Drug interactions for hyperthyroid drugs?
Lithium, iodine, warfarin, digoxin.
Warnings and contraindications of anti-hyperthyroid drugs?
Use with caution if low leucocyte count, avoid if hypersensitivity to sulphur-containing drugs or liver impairment. Contraindicated in pregnancy.
Additional drug therapies for hyperthyroidism?
Iodine and Iodides pre-surgery or radiation
>Lugol’s Solution (Aqueous Iodine Solution).
Radioactive iodine (131- I)
Indications thyroid carcinoma (beta particle
damage localized to thyroid), thyroid function test (avoid if breast feeding or pregnant).
β- adrenoceptor antagonists (β – blockers)
Used as adjunctive therapy to provide relief of symptoms due to peripheral effects of excess T4 (tachycardia, tremor, sweating).
CAM-based treatments of hyperthyroidism?
Green tea (Camellia sinensis). Standardized extract, for antioxidant effects. Use caffeine-free products.
Lemon balm (Melissa officinalis). To normalize an overactive thyroid.
Soy sterols (Genistein). Low doses of soy lowers the production of thyroid hormone in hyperthyroid patients.
Kale. Kale is considered to be goitrogenic, which means that when consumed in larger amounts it can potentially inhibit overactive thyroid function. Kale is one of the best sources of calcium. and it exhibits excellent absorbability for its calcium, improves bone density.
Mechanisms of action of hyperthyroid agents? Methimazole, PTU? SSKI's, Lugols? Beta blockers? PTU, glucocorticoids, propanolol?
Methimazole, PTU: Inhibition of T3 and T4 synthesis
SSKI’s, Lugols: block T3 and T4 release
Beta blockers: block hormone action
PTU, glucocorticoids, propanolol: block peripheral conversion of T4 to T3
The difference between type 1 and type 2 diabetes? the mechanism of action:
Type 1: β cells are destroyed eliminating the production of insulin.
Type 2: Inability of β cells to produce appropriate quantities of insulin; insulin resistance and other defects.
What are you treating in T1 or T2 diabetes:
why are drugs used for the treatment of Type 1 and Type 2 Diabetes Mellitus (DM).
Hyperglycaemia due to absolute (type 1) or relative (type 2) deficiency in insulin hormone; complex, chronic consequences of inability to process glucose.
What is DM (diabetes mellitus)?
DM is a metabolic disorder which arises from a dysfunction of the endocrine system and can lead to substantial morbidity and mortality due to the condition itself and the subsequent complications that result from poor control and management.
What are general aims of treatment of DM?
Obtain metabolic control with insulin, oral hypoglycaemic drugs and / or non-pharmacological regimens.
In type 1 and refractive type 2, use of insulin to avoid acute and chronic consequences. In type 2, oral hypoglycaemics to avoid chronic consequences and prevent progression (progression: need for insulin).
Non pharmacological management (preventing acute and long-term complications). Essential and includes:
Diet
Exercise Patient education Self-monitoring
Foot care
Types of insulin used for the management of DM
Ultra rapid-acting Short-acting Intermediate- acting Long-acting Combinations
Ultra rapid-acting insulin:
Mimics the normal physiological response to glucose
very rapid onset of action (10-15 minutes) so it can be taken immediately before meals.
Its short duration of action reduces the incidence of hypoglycemia 2-4 hours post- prandial.
Short acting insulin:
Short-acting
Rapid onset of action (0.5-1 hour)
Continue to exert an effect for up to 8 hours.
Can be given intravenously in emergency cases (e.g. ketoacidosis).
Intermediate acting insulin?
Onset of action is still relatively short (1-2 hours) but the duration of action extends up to 24 hours.
Long acting insulin?
Very slow onset (2-4 hours) with a prolonged duration of action (up to 36 hours).
Long-acting preparations are often used to provide a basal amount of insulin which is then “topped-up” with rapid-, short- or intermediate- acting insulin doses before meals.
