29.13 Antidiabetic Agents

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Included In This Lesson



  1. I. Overview

    A.    Diabetes management

    B.    Goal = Normoglycemia within 2-3 months

    1.     Diet

    2.     Exercise

    3.     Smoking cessation

    C.     If not achieved with lifestyle changes

    1.     Medications added

    II. Mechanism of Action

    A.    Sulfonylureas

    1.     Stimulating insulin secretion from the beta cells of the pancreas

    B.     Meglitinides

    1.     Stimulating insulin secretion from the beta cells of the pancreas

    C.     Biguanide

    1.     Decreasing the production of glucose / increase uptake

    D.    Thiazolidinediones

    1.     Enhancing sensitivity of insulin receptors

    a.     Liver, skeletal muscle and adipose tissue

    E.    α-Glucosidase Inhibitors

    1.     Delays glucose absorption

    a.     Blocking enzyme, α-glucosidase

    III. Types

    A.    Sulfonylureas

    1.     First Generation

    a.     Acetohexamide

    b.     Chlorpropamide

    c.     Tolazamide

    d.     Tolbutamide

    2.     Second Generation

    a.     Glimepiride

    b.     Glipizide

    c.     Glyburide

    B.    Meglitinides

    2.     Repaglinide

    3.     Nateglinide

    C.     Biguanide

    4.     Metformin

    D.    Thiazolidinediones

    5.     Troglitazone

    6.     Pioglitazone

    7.     Rosiglitazone

    E.     α-Glucosidase Inhibitors

    8.     Acarbose

    9.     Miglitol

    IV. Indications

    A     Lower the blood glucose levels

    1.     Diet and lifestyle changes fail

    V. Contraindications

    A.    Drug allergy

    B.    Active hypoglycemia

    C.      Severe liver or kidney disease

    1.     Depending on the required metabolic pathways

    D.      Pregnancy

    1.     Insulin therapy is preferred

    VI. Interactions

    A.     Sulfonylureas

    1.     Hyperglycemia

    a.     Alcohol

    b.     β-blockers

    c.     MAOIs

    d.     Oral anticoagulants

    e. Sulfonamides

    2. Hypoglycemia

    a.    Herbal supplements

    i.   Garlic

    ii.   Ginseng

    B.     Meglitinides

    1.  Increased effects

    a.     Fluconazole

    b.     NSAIDS

    c.     Sulfonamides

    2.  Reduced effects

    a.     Phenobarbital

    b.     Phenytoin

    c.     Carbamazepine

    d.     Thiazide diuretics

    C.   Biguanide

    1.  Increased effects

    a.     Furosemide

    b.     Nifedipine

    2.  Lactic acidosis / acute renal failure

    a.     Iodine-containing radiologic contrast media

    D.    Thiazolidinediones

    1.  None

    E.    α-Glucosidase Inhibitors

    1.  Hyperglycemia

    a.     Diuretics

    b.     Corticosteroids

    c.     Thyroid replacement hormones

    d.     Antiepileptic drugs

    VII. Side Effects

    A.     Sulfonylureas

    1.     Agranulocytosis

    2.     Hemolytic anemia

    3.     Thrombocytopenia

    B.    Meglitinides

    1.  Headache

    2.  Hypoglycemia

    3.  Dizziness

    4.  Weight gain

    C.    Biguanide

    1.  Abdominal bloating

    2.  Nausea

    3.  Cramping

    4.  Diarrhea

    D.     Thiazolidinediones

    1.  Weight gain

    2.  Edema

    D.     α-Glucosidase Inhibitors

    1.  Flatulence

    2.  Diarrhea

    3.  Abdominal pain

Patient Education

I. Signs of hypoglycemia

A. Shakiness
B. Dizziness
C. Sweating
D. Hunger
E. Moodiness
F. Anxiety

II. Signs of hyperglycemia

A. Increased thirst
B. Trouble concentrating
C. Blurred vision
D. Frequent urination
E. Fatigue
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Welcome back and today we are going to cover oral antidiabetic agents.

There are five types of oral antidiabetic agents. Please see the NRSNG presentation regarding insulin pharmacology, if needed. Sulfonylureas and meglitinides both stimulate insulin secretion (which lower blood glucose) from beta cells in the pancreas. Why the pancreas? Well the pancreas is apart of the endocrine system with one of its functions is to produce insulin. It’s the perfect site for glucose management. Lastly, we have biguanides, which decrease the production of glucose in the liver. Why the liver? Well one of the liver’s function, if filtering blood and remember glucose, attaches to hemoglobin? Yes, another great site!

The last two are unique drug classes. Thiazolidinediones work by enhancing the insulin receptors (allowing insulin function to work more efficiently) in various places – liver, skeletal muscle and adipose tissue. While a-Glucosidase inhibitors work by delaying glucose absorption (which increases blood glucose) but blocking the enzyme. Why these alternative options? Well, sometimes traditional medications aren’t effective and other routes of glucose management must be used. Depending on your patient’s organ function and performance, each drug class work responds differently to each patients.

The types of sulfonylureas have two generations, with most ending in -IDE. Now, sulfonylureas stimulate insulin secretion (which lower blood glucose) from beta cells in the pancreas. When you think on sulfonylureas think about the pancreas and the drugs ending in -IDE.
As mentioned before, meglitinides stimulate insulin secretion (which lower blood glucose) from beta cells in the pancreas, with medications ending in -GLINIDE. Biguanides decrease the production of glucose in the liver and the #1 drug in this class is metformin. Metformin is the preferred initial pharmacologic agent for the treatment of type 2 diabetes according to the American Diabetes Association. When patients are diagnostic with diabetes (type 2), their first drug prescribed is Metformin (if lifestyle changes are not effective). It’s a great drug and at most pharmacies the drug is free of charge.

Thiazolidinediones work by enhancing the insulin receptors in various places – liver, skeletal muscle and adipose tissue with drugs ending in -GLITAZONE. While a-Glucosidase inhibitors work by delaying glucose absorption (which increases blood glucose) but blocking the enzyme – with two drugs acarbose and miglitol.

Antidiabetic oral agents are indicated when lowering of blood glucose is needed and lifestyle changes have failed. Now, if our goal is to lower blood glucose we have to make sure we don’t cause hypoglycemia (and cause dangerously low levels). Why is glucose important? Glucose if the primary source of energy for the body, especially the brain. Lack of the important source causes various temporary and even permanent effects (which we will discuss later in the lecture).

Contraindications include allergies, hypoglycemia (as these drugs lower glucose levels), liver & kidney disease (as these drugs are metabolized or excreted using these organs) and pregnancy (as insulin is preferred – as it doesn’t cross the placenta and is safe for the baby). I had a patient who was taking an oral antidiabetic agents but kept having hypoglycemic events. The patient ended up needing to see an endocrinologist has their blood glucose level couldn’t be managed properly. An endocrinologist is a specialist who can manage patients with complicated glucose cases.

Sulfonylureas have hyperglycemic interactions with combined with alcohol, beta-blockers, MAOIs, anticoagulants and sulfonamides. It also has hypoglycemic interactions with herbal supplements, mainly garlic and ginseng. If your patient is taking herbal supplements, it is important they know about these interactions as hypoglycemia can occur.
Now meglitinides will have increased and decreased effects with medications mentioned here. What does that mean? It means your patients can experience hyperglycemia (due to reduced effects and medication not being effective) or hypoglycemia (due to increased effects and medication efforts be potentiated). It is important to ask your patients what other medications they are taking as others can alter the function of the antidiabetic agents. I had a patient who was taking nateglinide and phenobarbital, as a result, their blood glucose remain elevated.

Metformin’s effects will be increased with the use of furosemide and nifedipine. One unique feature of metformin is its ability to cause lactic acidosis and acute renal failure with used with iodine-containing radiologic contrast media. Contrast media is used during certain diagnostic testing, commonly computerized tomography (CT) scans are the tests. If a patient is getting a CT scan with contrast, it is recommended that metformin be withheld after the administration of the contrast agent for 48 hours (in order to prevent acute renal failure).
α-Glucosidase Inhibitors are linked to hyperglycemia with administered with the following drugs. If you have a patient with uncontrolled diabetes, the first question should be, “What other medication are you taking?” Because oftentimes, it interaction and not due to noncompliance. As thyroid and antiepileptic medications are life-long drugs, it’s critical to ask these types of questions.

Side effects of sulfonylureas are blood based and include agranulocytosis (severe leukopenia), hemolytic anemia (destruction of red blood cells) and thrombocytopenia (low platelet count). So, if you have a patient who has a blood disorder, this drug class might not be the best match.

Side effects of meglitinides focus on headache, low blood glucose, dizziness and weight gain. While side effects of biguanides focus on the GI tract (bloating, nausea, cramping and diarrhea).

Nursing concepts for antidiabetic agents include glucose metabolism and pharmacology.

Let’s review. There are various mechanisms of actions with most focusing on the stimulation of insulin receptors and the decreased or delay of glucose production. Indications include lowering blood glucose levels, while contraindications revolve around hypoglycemia, liver/kidney disease and pregnancy. Interactions are plentiful and drug class based but include herbal supplements, diuretics and beta blockers (to name a few). And lastly, side effects are blood and GI tract based. Patient education is crucial as hyper- and hypo- glycemia can cause serious complications.

And now you know all you need to know about antidiabetic oral agents. Now go out and be your best self and as always happy nursing!


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