61. Corticosteroids

Introduction

The corticosteroids are hormones released from the adrenal cortex. We distinguish two types of corticosteroids, the glucocorticoids and the mineralocorticoids. The release of glucocorticoids is stimulated by ACTH. The level of ACTH, and therefore glucocorticoids, follows a diurnal rhythm, meaning that it is at its highest at 8:00 and at its lowest at midnight.

Effects of glucocorticoids

The effects of glucocorticoids on the body explains all pharmacological indications and possible side-effects of glucocorticoid therapy.

The metabolic effects involve decreased glucose uptake and utilization, decreased protein synthesis, increased protein breakdown, increased ketone body synthesis and increased lipolysis. In high, non-physiological doses glucocorticoids will have mineralocorticoid-like effects due to the spillover-mechanism, causing Na+ retention and K+ loss. There will also be a negative Ca2+ balance, causing osteoporosis.

Glucocorticoids elicit most of their effects by binding to the intracellular glucocorticoid receptor, which alters gene transcription and represses pro-inflammatory genes and induces anti-inflammatory genes. These genomic effects take long time to set in. However, glucocorticoids also have so-called non-genomic effects, which occur within minutes of administration. These non-genomic effects involve decreased leukocyte migration and decreased capillary permeability and vasodilation. The latter two have an anti-oedema effect.

Pharmacology of glucocorticoids

Many glucocorticoids are used pharmacologically, where they’re often called “steroids”. Most of them are synthetic. They differ in their potency in activating the glucocorticoid receptor, their degree of activating the mineralocorticoid receptor, their degree of systemic and local effectiveness and their duration of action.

Name Potency as glucocorticoid Potency as mineralocorticoid Relative systemic effectiveness Relative local effectiveness Duration of action
Cortisol/hydrocortisone

1

1 1

1

Short

Cortisone

0.8

0.8

Short

Prednisolone

4

0.8 5

2

Intermediate

Methylprednisolone

5

0.5 5

5

Intermediate

Triamcinolone

5

0 5

1

Intermediate

Betamethasone

30

0 30

5 – 10

Long

Dexamethasone

30

0 30 – 120

10

Long

Fluticasone

~0 40 – 100

Budesonide

The potency as glucocorticoid and mineralocorticoid is measured relative to the potency of cortisol. Hydrocortisone and cortisol are the same molecule, but in a pharmacological setting we use the name hydrocortisone.

The numbers of the above table aren’t that important to know. What’s important to know is that different glucocorticoids have different properties that make them better for certain indications than others. For example, fluticasone and budesonide are only used locally.

Indications:

The list of indications for glucocorticoids is endless. It’s mostly used for symptomatic treatment, either locally or systemically. Here are some of the most important indications:

  • As substitution therapy
    • In primary adrenal insufficiency (Addison’s disease)
    • In secondary adrenal insufficiency
    • In tertiary adrenal insufficiency
    • Drug of choice is hydrocortisone or cortisone
  • As systemic symptomatic therapy
    • Acute
      • Allergic reactions and anaphylactic shock
      • Asthma attack
      • Antiemetic treatment (especially due to cytostatic treatment)
      • Acute exacerbation of autoimmune diseases like MS, psoriasis
      • Acute exacerbation of COPD
      • Cerebral oedema – only dexamethasone
    • Chronic
      • Asthma
      • COPD
      • Inflammatory bowel disease
      • Sarcoidosis
      • Sjögren syndrome
      • SLE
      • Rheumatoid arthritis
  • As local symptomatic treatment
    • Skin diseases
    • Ear diseases
    • Eye diseases
  • Organ transplant
  • To distinguish between different types of Cushing syndrome
    • As part of the dexamethasone suppression test
  • Preterm delivery
    • Glucocorticoids given to the mother induce foetal lung maturity

People who are on substitution therapy with glucocorticoids should increase their dose of glucocorticoids in cases of stress, like infections, surgery or trauma. These types of stress can increase the body’s need for cortisol by a factor of 10. If this demand is not met, the patient can develop an adrenal crisis due to relative lack of cortisol, which can be fatal.

Dosing:

Glucocorticoids are available in many different drug formulations. Local treatment is preferred over systemic treatment where possible, to prevent systemic side-effects. Drug formulations like ointments, creams, eye drops, ear drops, nasal sprays, intraarticular injections and inhalation aerosols all allow for local treatment.

Most glucocorticoids have good oral absorption, so for chronic systemic treatment oral preparations are often used. Long-term systemic steroid therapy causes atrophy of the adrenal cortex. If long-term (> 3 weeks) steroid therapy is discontinued suddenly the body will experience relative cortisol deficiency, potentially causing an adrenal crisis. Long-term steroid therapy should only be terminated gradually, to prevent this. Taking steroids every second day may help limit adrenal atrophy. We should always strive to find the lowest dose that is still effective, to limit side effects.

Pharmacokinetics:

90% of endogenous glucocorticoids are bound to a transport protein called corticosteroid-binding globulin (CBG). Synthetic glucocorticoids like dexamethasone and betamethasone don’t bind to CBG and therefore act more rapidly than non-synthetic glucocorticoids.

All glucocorticoids are small lipophilic molecules that easily penetrate through biological membranes.

Hydrocortisone is inactivated by the liver and then excreted by the kidneys. Cortisone is a prodrug which is converted into hydrocortisone in the liver.

Side effects:

Side effects usually develop during chronic treatment, and rarely during short-term treatment. The potential side effects of steroid treatment has been described many times before, but here are some of them:

  • Skin atrophy
  • Purple stretch marks
  • Hypertension
  • Central weight gain, buffalo hump, moon face
  • Hyperglycaemia/diabetes
  • Osteoporosis
  • Muscle weakness

Contraindications:

There are (logically) no contraindications for people who require glucocorticoid as substitution therapy. These contraindications are for those that receive symptomatic steroid therapy.

  • Allergy
  • Systemic fungal infections
  • Concomitant live virus vaccination

Glucocorticoids should be used with care in people with psychosis, diabetes, ulcers, severe hypertension and pregnant women.

Pharmacology of mineralocorticoids

Mineralocorticoids are used pharmacologically only in substitution treatment of primary adrenal insufficiency (Addison disease) and the most common type of congenital adrenal hyperplasia (21β deficiency). Both conditions are treated with life-long substitution with cortisol and fludrocortisone.

Drugs acting on corticosteroid synthesis

Metyrapone inhibits cortisol synthesis by inhibiting the enzyme 11β-hydroxylase, an enzyme involved in cortisol synthesis. It’s used to treat Cushing syndrome.

Ketoconazole is an antifungal drug which also inhibits 17α-hydroxylase, an enzyme involved in cortisol synthesis. It’s used to treat Cushing syndrome.

Aminoglutethimide decreases corticosteroid synthesis but is no longer available due to its toxicity.


Previous page:


Next page:
62. Estrogens, antiestrogens, progestins, antiprogestins

2 thoughts on “61. Corticosteroids”

Leave a Reply

Only the "Comment" field must be filled in. It is not compulsory to fill out your name; you can remain anonymous. Do not fill out e-mail or website; if you do, your comment will not be published.