Systemic drugs for psoriasis are available in oral and injectable forms. There are several options from which the doctor can choose a drug that best suits the patient.

Psoriasis is a chronic inflammatory disease involving multiple systems but primarily affecting the skin and the joints.

Topical application with steroids, vitamin D3 analogs, or their combination remains the first line of treatment for mild to moderate cases.

More severe cases with symptoms that cannot be controlled and are resistant to topical applications and phototherapy may require systemic therapy with oral and/or injectable medication.

Systemic drugs for psoriasis have been around for many years but have seen a lot of development, especially in the injectable category. New drugs are available that give significant relief to the patient.

However, these oral pills and injections (part of systemic therapy) have severe side effects, which necessitate their use for a short period only and are often alternated with other treatments.

Oral psoriasis drugs

1. Acitretin

Brand name Soriatane

Acitretin is an oral second-generation retinoid that is typically used in the treatment of psoriasis. Retinoids are synthetic vitamin A chemical compounds, which help in psoriasis cure by regulating the growth of the epithelial skin cells by modulating the immune system.

Acitretin is not without side effects, which can be serious. For this reason, your doctor will prescribe this drug for a short duration as required. Once the remission sets in, he will ask you to stop the drug till you face another flare-up.

Common side effects include:

Rarely, you may see some serious adverse effects;

  • loss of night vision
  • severe headaches
  • chest pain
  • shortness of breath
  • difficulty speaking

2. Methotrexate (MTX)

Brand name: Rheumatrex

Methotrexate was originally developed and is still used in chemotherapy for the treatment of cancer. It belongs to a class of drugs called antimetabolites.

Being an immunosuppressant (suppresses the immune system of the body), it has been found to be beneficial in the treatment of autoimmune diseases like psoriasis, Crohn’s disease, and rheumatoid arthritis. However, its doses for these diseases are small.

It is used to treat severe forms of psoriasis and is taken orally. Due to its depressive action on the T cells of the immune system, it inhibits the overproduction of skin cells (which occurs in psoriasis) and reduces inflammation.

It is mainly used to treat pustular psoriasis, erythrodermic psoriasis, and widespread plaque psoriasis with good effect. It is also beneficial in the treatment of psoriatic arthritis.

Common side effects include fever with chills, fatigue, nausea, dizziness, loss of appetite, and recurrent infections. Folic acid helps to protect against some of these side effects.

Serious life-threatening side effects with high doses include bleeding which can occur through urine, yellowing of skin and /or eyes, allergic reactions that may cause trouble breathing, skin rash, or hives. It also exhibits liver toxicity and renal toxicity properties.

3. Cyclosporine

Generic name: Cyclosporine

Brand name: Neoral, Gengraf, Sandimmune

Cyclosporine or Ciclosporin (as it is sometimes spelled) is a strong immunosuppressant oral drug (suppresses the immunity of the body), similar in effectiveness to Methotrexate.

You use it in the treatment of severe forms of psoriasis that is widespread and difficult to treat. It was first used to prevent organ rejection after an organ transplant.

It was then approved as late as 1997 by the FDA of the United States for the treatment of severe psoriasis in adults with a normal immune system.

Some common side effects include headache, fever, pain in the stomach, diarrhea, shortness of breath, tachycardia, an increase in blood pressure, and excessive fatigue.

Cyclosporine also causes drug interactions with other drugs including those used to treat psoriasis, kidney damage, increased risk of infections, and nervous system problems.

4. Apremilast

Apremilast is a new arrival that provides a potent treatment for plaque psoriasis and psoriatic arthritis. It produces significant improvement in the symptoms of plaque, nail, and scalp psoriasis

Apremilast works by controlling inflammation through its action on the immune cells. It reduces the redness, itching, and scales formed on the skin surface caused by psoriasis. It acts with equal efficacy in both young and old.

Mild side effects include fever, cold, vomiting, diarrhea, and stomach pain. Other possible problems include weight loss, adverse effects on kidney disease, and drug interactions with other drugs including anti-seizure drugs.

Injectable psoriasis drugs

1. Biologics

For a moderate to severe degree of psoriasis that has not responded to topical applications and phototherapy, your dermatologist will put you on injectable drugs known as biologic drugs or biologics.

These drugs are administered by injection either by intravenous, intramuscular, or subcutaneous routes.

They are manufactured proteins and have a very powerful action on the immune system. Unlike the other systemic traditional drugs, they target only the specific parts of the immune system.

Their action targets a specific type of cell of the immune system called the T-cell and proteins in the immune system, such as tumor necrosis factor-alpha (TNF-alpha), interleukin 17-A, or interleukins 12 and 23.

These very cells and proteins are responsible for the development of symptoms of psoriasis and psoriatic arthritis (PsA).

The following are examples of biologics with their generic and brand names along with their mechanism of action.

  • Tumor Necrosis Factor-Alpha (TNF-alpha) Inhibitors. TNF-alpha is a cytokine that creates inflammation in the body. In psoriasis and other autoimmune diseases such as psoriatic arthritis, rheumatoid arthritis, Crohn’s disease, and SLE, there is excess production of TNF-alpha within the skin and the joints that leads to excessive growth of the skin cells and damage to the joints. Blocking the actions of TNF-alpha prevents the inflammation from flaring up. Examples include:
    • Cimzia (certolizumab pegol)
    • Enbrel (etanercept)
    • Humira (adalimumab)
  • Interleukin 12 and 23 (IL-12, IL-23) Inhibitors. Stelara selectively blocks the action of cytokines IL-12 and IL-23, which are associated with the inflammation seen in psoriasis. Example include:
    • Stelara (ustekinumab)
  • Interleukin 17 (IL-17) Inhibitors. The Il-17 inhibitors selectively target the protein IL-17 that is associated with the inflammation of psoriasis and block its action. Examples include:
    • Cosentyx (secukinumab)
    • Siliq (brodalumab)
    • Taltz (ixekizumab
  • Interleukin 23 (IL-23) Inhibitors. In a similar fashion, IL-23 inhibitors selectively block the action of the protein or cytokine IL-23, which is responsible for psoriatic inflammation.
    • Ilumya (tildrakizumab-asmn)
    • Skyrizi (risankizumab-rzaa)
    • Tremfya (guselkumab)
  • T-cell inhibitors. T-cells are a type of white blood cell, which play an important part in the immune function of the body and is responsible for the inflammation of psoriasis. Orencia selectively targets these cells and inhibits their growth thereby controlling the infection. Example include:
    • Orencia (abatacept)

2. Methotrexate Injectable form

Besides its oral form described above, methotrexate is also available as an injectable, which can be administered intramuscularly (into a muscle) or subcutaneously (under the skin). A prefilled auto-injector pen has recently been developed. This allows the patients to inject and treat themselves with this pre-filled pen at home.

Moderate to severe cases of psoriasis do not respond to topical treatments. Your doctor might then recommend an injectable drug such as methotrexate (brand names: Otrexup, Rasuvo, and Trexall) besides biologics. This can help clear up plaques and reduce inflammation.