Antidiabetic Drugs, Anti-thyroid Drugs and Oral Contraceptives Flashcards
Where are the hormones thyroxine/levothyroxine (T4) and tri-iodothyronine (T3) made from?
(Both under the control of TSH)
Thyroid gland
What hormone is produced by C (parafollicular) cells of thyroid gland?
Calcitonin
Hypothalamus -> Anterior Pituitary -> Thyroid Gland
State the hormones released at each structure.
TRH -> TSH -> T4 and T3
TRH = thyrotropin releasing hormone; TSH = thyroid stimulating hormone
What ions are thyroid hormone production dependent upon?
Iodide
What are thyroid hormones stored as?
Thyroglobulin
Thyroglobulin undergoes _________ to release hormones
Proteolysis
Which is more potent - T3 or T4?
T3
What does T4 become after undergoing transformation in the tissues?
T3
What do the T3 and T4 hormones influence?
DNA transcription and thus protein synthesis
What do thyroid hormones do?
Regulate growth: brain development
Calorigenic effects: increase O2 consumption (effect on BMR)
Metabolic effects: transform cholesterol to bile salts; increase lipolysis; increase blood glucose; increase metabolic rate
Cardiovascular effects: direct; indirect (increase sensitivity to catecholamines via beta receptor expression)
What are the causes of hypothyroidism in children?
Congenital hypothyroidism (causing cretinism)
Hashimoto’s thyroiditis (acquired autoimmune disease; usually affect teens; most common cause of hypothyroidism)
Cretinism: intellectual disability,small stature,thick facial features
What are the causes of thyroid hypofunction in adults?
Autoimmune destruction
Post surgery
What are the clinical features of myxoedema which is caused by thyroid hypofunction?
Puffiness of skin
Exopthalmous (deposition of protein and mucopolysaccharides leading to abnormal protrusion of eyeballs)
What does thyroid hypofunction cause?
Impaired immune response
What is the second most common endocrine disorder after diabetes mellitus?
Thyroid disease
What is the treatment of thyroid hypofunction?
Levothyroxine sodium (orally) for maintenance
What autoimmune disease can be acquired and cause hyperthyroidism?
Graves’ disease (diffuse goitre)
What clinical features will be present in patients with thyroid hyperfunction?
Anxiety
Tremor
Increase heart rate
Muscle weakness
Insomnia
What are the 3 methods of treating hyperthyroidism?
Antithyroid drugs eg carbimazole and propylthiouracil
Potassium iodide
Radioactive iodine
Control the production of T3 and T4
What are the 2 antithyroid drugs?
Carbimazole
Propylthiouracil
How do carbimazole and propylthiouracil work?
The ‘thionamides’ or ‘thiourylenes’ prevent incorporation of iodine into T3 and T4.
Propylthiouracil also stops conversion of T4 to T3.
What is the most commonly used drug to treat hyperthyroidism in the UK?
Carbimazole
When is propylthiouracil used instead of carbimazole?
If intolerant or sensitive to carbimazole
In 1st trimester of pregnancy
When is iodine given as treatment for thyroid hyperfunction?
Short term only prior to partial thyroidectomy
What are some unwanted side effects of antithyroid medications?
Thionamides: agranulocytosis, urticarial rash, hepatitis, arthralgia
Iodine-containing preps: hypersensitivity reactions (angioedema)
Radioactive iodine: hypothyroidism
What influences calcium and phosphate metabolism?
Calcitonin
What hormone does calcitonin oppose?
Parathyroid hormone (PTH)
What does calcitonin produce?
Hypocalcaemia
Hypophosphataemia
How does calcitonin work?
Inhibition of osteoclasts
Osteoclasts break down bone and release calcium into bloodstream
What is calcitonin used to treat?
Hypercalcaemia
Paget’s
What are the different types of calcitonin and how to administer calcitonin?
Salmon, eel, pig or synthetic human calcitonin
SC or IM injection
What needs to be avoided in uncontrolled hyperthyroidism?
Adrenaline
What could Candidiasis be a possible indication of?
Reduced immune response in hypothyroidism
What medications may taste disturbance be caused by?
Calcitonin
Carbimazole
Propylthiouracil
What can cause damage to salivary glands?
Radioactive iodine
What is type 1 diabetes mellitus due to?
Deficiency of insulin
What is type 2 diabetes mellitus due to?
Decreased insulin secretion or resistance to insulin action
How to treat diabetes?
Supply insulin
Increase insulin intake
Decrease glucose intake
Decrease glucose uptake
What can inactivate insulin?
Gut enzymes
therefore cannot be taken intraorally
Insulin can be administered parenterally. For maintenance, __________ injection. For emergency, ___________ injection.
Subcutaneous, intravenous
What is the insulin adminestered through inhalation called?
Afrezza
Not currently available on NHS
What type of insulins are there?
Animal insulin
Human insulin eg Humulin
Human analogue insulin (subgroup of human insulin) eg rapid acting, long acting, intermediate acting
What are some examples of insulin regimens?
Once-daily insulin regimen
Twice daily insulin regimen or Biphasic
Basal-bolus regimen / multiple daily injection therapy
Continuous subcutaneous insulin infusion (CSII) / insulin pump therapy
Once-daily insulin regimen:
Type _ diabetes supplemental to ______ __________
2, oral hypoglycaemics
Twice daily insulin regimen or Biphasic:
Mix of short and _______ acting insulin
Intermediate
Basal-bolus regimen / multiple daily injection therapy:
Type _ commonly
More flexible and tailorable to meal
Use of basal intermediate or long acting and separate short or rapid acting insulin
1
CSII / insulin pump therapy:
Type _
Rapid insulin continuously
Adjustable
1
Soluble insulin may cause ____ and _____ of the salivary glands
Pain, swelling
What may inhaled insulin cause?
Dry mouth
If GA involved dental procedure, usually involves checking __________.
HbA1c
Which drug class can produce hypoglycaemia?
And should be used with caution?
NSAIDs
What drug class can antagonise the hypoglycaemic effect of insulin?
Systemic steroids
When should oral hypoglycaemics be used?
Only after >3 months of diet and exercise to try and control T2 diabetes and afterwards as a supplement to lifestyle factors
What are some classes of oral hypoglycaemics?
Sulphonylureas
Biguanides
Thiazolidinediones (glitazones)
Alpha-glucosidase inhibitors
Sulphonylureas are used to _________ insulin secretion, but must have functional beta cells. They are for those who are not _________ or those who cannot take ________. Examples of sulphonylureas include _______, _______ and tolbutamide. Sulphonylureas can be used in combination with other oral hypoglycaemic drugs.
Augment, overweight, metformin, gliclazide, glipizide
Sulphonylureas are used to _________ insulin secretion, but patients must have functional beta cells. They are for those who are not _________ or those who cannot take ________. Examples of sulphonylureas include _______, _______ and tolbutamide. Sulphonylureas can be used in combination with other oral hypoglycaemic drugs.
Augment, overweight, metformin, gliclazide, glipizide
Biguanides can only act in the presence of ______ so it will only work in patients with functional beta cells. Biguanides decrease ____________ and increase peripheral utilisation of __________. They are first choice of drug for _______ patients. An example of biguanide is metformin.
Insulin, gluconeogenesis, glucose, overweight
Other oral hypoglycaemic drugs:
_________ inhibits intestinal α-glucosidases delays the digestion and absorption of starch and sucrose
‘________’ (pioglitazone) reduce peripheral insulin resistance, leading to a reduction of blood-glucose concentration
‘Gliptins’ (Alogliptin, linagliptin, saxagliptin) inhibit dipeptidylpeptidase-4 to increase insulin secretion and lower glucagon secretion
‘______’ (Exenatide, albiglutide, dulaglutide) bind to, and activate, the GLP-1 (glucagon-like peptide-1) receptor to increase insulin secretion, suppress glucagon secretion, and slow gastric emptying
‘______’ (Canagliflozin, dapagliflozin, empagliflozin) reversibly inhibit sodium-glucose co-transporter 2 (SGLT2) in the renal proximal convoluted tubule to reduce glucose reabsorption and increase urinary glucose excretion
Acarbose
Glitazones
Gliptins
Tides
Gliflozin
What oral hypoglycaemic drug may cause lichenoid eruptions, erythema multiforme and oral neuropathy?
Sulphonylureas
What oral hypoglycaemic drug can produce taste disorders?
Metformin
How to treat patients who are having hypoglycaemic episodes?
Oral glucose 10-20g (3 sugar lumps/2 teaspoon of sugar/100ml sugary drink/Glucogel)
If unconscious: 1mg IM or SC glucagon; less commonly available IV glucose 20-50ml of a 50% dextrose solution
Combined oral contraceptive: ________ and ________. __ days active, __ days inactive.
Oestrogen and progesterone. 21, 7.
____________-only oral contraceptive: continuous use. ‘mini pill’. Used when oestrogens contra-indicated eg predisposition to venous thrombosis.
Progesterone
For patients who do not want to take progesterone-only oral contraceptive tablet everyday, what can they opt for?
Progesterone-only depot injection or implant
What is in ‘morning after’ pill?
Oestrogen only
How does oestrogen work?
Inhibits ovulation by inhibition of FSH
How does progesterone work?
Inhibits release of LH, changes the endometrium to discourage implantation and thickens cervical mucus (prevents sperm from entering uterus)
What effects do oral contraceptives cause that are related to dentistry?
Increase plaque-induced inflammation
Increase gingival crevicular fluid
Gingival pigmentation
Appear to increase the incidence of dry socket
Improves severity of oral aphthous ulceration related to menstruation
May increase post-operative pain
Anticonvulsants eg __________ (enzyme-inducing) can stop oral contraceptives from working.
Carbamazepine
What type of antibiotics will cause a problem when taking together with oral contraceptives? Give an example.
Enzyme-inducer eg rifampicin
Are routine dental antibiotics enzyme-inducers?
No
What should be recommended to patients who are taking enzyme-inducing antibiotics while using hormonal contraception?
Additional contraceptive methods such as condoms or IUD
If antibiotics other than rifampicin and rifabutin are taken, additional contraception is not usually needed. However, concerns arise when symptoms such as _________ or _________ come up. The effect of the antibiotics on gut flora and enterohepatic cycling can affect the absorption of the oestrogen pills.
Diarrhoea, vomiting.
What are the two drugs we need to be concerned about interacting with oral contraceptives?
Enzyme-inducing anticonvulsants eg carbamazepine
Antibiotics (enzyme-inducing eg rifampicin; non-enzyme-inducing but cause diarrhoea or vomiting)
