Guselkumab - Uses, Dosage, Precautions, Side Effects, and More

Overview:

Guselkumab is a drug developed by a US-based company called Janssen Biotech. The drug was approved by the FDA (Food and Drug Administration) in 2017. Guselkumab is approved to treat moderate to severe psoriasis and psoriatic arthritis. Psoriasis is thought to be an autoimmune condition that causes redness, itching, scales, and plaques on the skin. Guselkumab, administered as a psoriasis medication injection, is also being tested to manage other autoimmune conditions such as pustular psoriasis, psoriatic arthritis, Crohn's disease, rheumatoid arthritis, etc.

How Does Guselkumab Work?

Guselkumab's mechanism of action binds to the p19 subunit of IL-23 with human immunoglobulin G1 (IgG1) monoclonal antibodies (mAb). The drug is the first of its class to be approved for the treatment of mild to moderate plaque psoriasis in adult patients by the Food and Drug Administration (FDA) of the United States and the European Medicines Agency (EMA), which are candidates for systemic treatment or phototherapy. Furthermore, due to its clinical effectiveness in the treatment of plaque psoriasis, Guselkumab is being investigated for the treatment of other diseases, such as generalized pustular psoriasis (GPP), erythrodermic psoriasis (EP), psoriatic arthritis, rheumatoid arthritis, and Crohn's disease (chronic inflammatory disease of the digestive tract).

An increase in TNF (tumor necrosis factor) production is observed during the initiation phase of the psoriatic skin lesions, resulting in the activation of dermal dendritic cells. They produce an increased amount of interleukin 23 (IL-23) and activate distinct subsets of cells producing IL-17 (helper T-cells, cytotoxic T-cells, innate lymphoid cells, and γδ T cells). T17 cytokine cells increase and produce large amounts of IL-17, specifically isoforms IL-17A, and IL-17F, which trigger the upregulation of many psoriasis-related genes as IL-23 levels rise, which is secreted primarily by inflammatory dermal dendritic cells. As a result of the clonal expansion of T17 cells and IL-17 production, keratinocyte hyperproliferation occurs. IL-23 was also increased in macrophages and keratinocytes, which may contribute to the establishment and maintenance of psoriatic lesions. Pathogenic pathways leading to psoriasis are widely believed to involve the IL-23 or IL-17 axis. As a result of drugs targeting this pathway, the paradigm of dealing with this condition has changed.

In the development of IL-17 inhibitors, it was shown that blocking this cytokine pathway exhibited high levels of efficacy and onset of action faster than TNF inhibitors, and Ustekinumab, a nonselective IL-23 inhibitor, produced better clinical outcomes. However, several side effects have been associated with these agents, notably neutropenia, candidiasis, and exacerbation of Crohn's disease, thus reinforcing the need for new therapies. Several selective IL-23 inhibitors have emerged recently, showing efficacy, durability, and safety. These include Guselkumab, Tildrakizumab, and Risankizumab.

What Is Guselkumab Used For?

Guselkumab is formulated for psoriasis injection, thereby modulating immune signals that cause inflammation in autoimmune disorders. Psoriasis is an autoimmune disease that produces redness, itching, scaling, and thickening of patches of skin. Despite having no known regular cure, other treatment options, such as Guselkumab, aim to ease the symptoms of the condition to enhance the patient’s quality of life. Psoriasis is a long-term skin disease that has variability in terms of times of worsening of the disease and periods of remission, and the treatment options are based on the disease stage and therapeutic history.

Dosage:

Guselkumab is administered subcutaneously (beneath or under the layers of skin).

100 mg of Guselkumab is administered at 0 and 4 weeks and every 8th week after that.

• Missed Dose: If a patient has missed the Guselkumab dose they have been supposed to take, they should consult with their healthcare provider. They will advise when the best time to give the missed dose is to ensure you are on the right schedule. It is important not to do so by taking another dose to make up for the one that has been missed. Consistency in the administration of Guselkumab is essential if the illness, such as psoriasis and psoriatic arthritis, is to be managed.

• Overdose: Guselkumab is usually injected under the skin, and on very rare occasions, it is cause for extreme concern to take an overdose of Guselkumab, given the method of its administration. However, the following effects may indicate that an overdose has occurred or that one is required, and if this is the case, you should consult a doctor immediately. Larger doses will prompt more chances of other side effects like severe immunosuppression or allergies.

Warning:

• Risk of Infection: Treatment with Guselkumab may increase the risk of infections. Patients were reportedly affected by gastroenteritis, upper respiratory tract infections, herpes simplex, tinea (fungal) infection, etc. However, the risk of acquiring a serious infection is less than 0.2 percent. If patients are already diagnosed with an active infection, Guselkumab treatment should not be initiated until the infection is under control or resolved. In case of chronic or recurrent infections, the risks and benefits of Guselkumab therapy should be considered.

• Risk of Tuberculosis (TB): Patients are at an increased risk of developing serious tuberculosis, especially with a past history of latent or active tuberculosis. Before starting Guselkumab treatment, patients must be evaluated for latent TB. If positive, the treatment for latent tuberculosis should start before Guselkumab administration. Constant monitoring for signs and symptoms of tuberculosis is needed during and after the administration of Guselkumab. In the case of active tuberculosis, anti-tuberculosis treatment can be initiated priorly. Guselkumab administration should be avoided in patients with untreated active TB.

• Live Vaccines: Patients should be immunized against all infections according to the current immunization guidelines. Although there is no evidence of response to live vaccines, the use of Guselkumab with live vaccines should be avoided.

• Allergies and Adverse Reactions: Some patients might experience mild symptoms of allergy, such as urticaria. However, it has been reported that less than 1 % of patients experienced headaches, diarrhea, arthralgia, etc. Additionally, some patients developed injection site reactions such as erythema, bruising, urticaria, swelling, hematoma, bleeding, edema, pruritus, discoloration, inflammation, induration, and pain.

• Elevated Liver Enzymes: Elevations in liver enzymes were frequently reported in patients receiving Guselkumab treatment. However, the elevations can be mild to moderate in severity.

For Patients:

What Is Psoriasis?

Psoriasis is a chronic skin disease characterized by red, scaly, and itchy patches on the skin. Commonly affected areas include the scalp, knees, elbows, and trunk. Psoriasis is an autoimmune condition that causes the skin cells to multiply ten times faster. As a result, skin cells build up as red patches with white scales. Nearly 2.2 percent of the world population is diagnosed with psoriasis. It may affect individuals of any age, but the prevalence is common between 15 and 25 years.

Immunology of Psoriasis:

Psoriasis is a chronic autoimmune condition, and the pathogenesis is not understood. However, it is attributed to genetics, epigenetics (environment and behavioral factors that cause changes in the gene without the involvement of DNA), and environmental factors. The characteristic feature of psoriasis is the excessive growth of keratinocytes (primary cells in the outermost layer of skin). The interaction between the keratinocytes and the inflammatory cells leads to symptoms. Inflammatory cells such as T-cells, particularly T-helper 1 (Th-1), T-helper 17 (Th-17), interleukin 12 (IL-12), and interleukin 23 (IL-23), play an essential role. These cells also increase the local inflammatory response by producing cytokines, chemokines, and antimicrobial peptides.

Note:

• T-cells - A type of white blood cell that plays a vital role in the immune system.

• Interleukins - A group of cytokines expressed on the surface of white blood cells.

• Cytokines - Proteins molecules that control the growth and activity of other immune cells.

• Chemokines - Family of cytokines that direct other immune cells, particularly leukocytes.

• Antimicrobial Peptides - Molecules that play a role in the host immune response.

What Are the Symptoms of Psoriasis?

• Red patches or plaques of skin covered with silvery-gray scales.

• Dry and itchy skin.

• Burning sensation or soreness of the affected area.

• Joint swelling and stiffness.

• Nail pitting and thickening.

• Bleeding from the affected site on scratching.

• Small scales on the skin.

What Are the Types of Psoriasis?

• Plaque Psoriasis: The most common form is characterized by red patches, plaques, and itchy and scaly skin.

• Nail Psoriasis: Finger and toenails are affected, causing pitting, discoloration, and abnormal growth.

• Guttate Psoriasis: Triggered by bacterial infection and commonly affects children and young adults.

• Inverse Psoriasis: Smooth red patches on the skin that occur mainly on the groin, buttocks, and breast skin folds.

• Pustular Psoriasis: A rare subtype of psoriasis characterized by pus-filled lesions on palms and soles.

• Psoriatic Arthritis: Mimics arthritis causing swelling, stiffness, and painful joints.

• Erythrodermic Psoriasis: The least common form of psoriasis that covers the entire body with red, patchy, and peeling skin.

What Is the Conventional Treatment of Psoriasis?

• Topical Medications: Involves the application of either steroids, retinoids, Vitamin D, or salicylic acid creams.

• Phototherapy: Exposure to sunlight and narrow-band UV (ultraviolet) light is the first line of treatment in moderate to severe cases of psoriasis.

• Systemic Therapy: Involves the systemic administration of steroids, retinoids, immunosuppressants, and biologics.

• Alternative Medicine: Several natural therapies involving aloe vera cream, essential oils, and fish oil supplements claim to relieve symptoms. However, the effectiveness of this approach is yet to be studied.

Learn More About Guselkumab:

Why and When to Switch to Guselkumab?

The conventional treatment of psoriasis includes steroids, retinoids, and immunosuppressant therapy. However, long-term topical application of corticosteroids can cause thinning of the skin. Eventually, corticosteroids stop working after a long-term application. Systemic corticosteroids also have several side effects. Retinoid therapy increases sensitivity to light and is not recommended in pregnant or lactating mothers. Immunosuppressants like Methotrexate can cause liver damage. Guselkumab belongs to a new group of drugs called biologics; it has fewer side effects and effectively relieves psoriasis symptoms.

What Differentiates Guselkumab From Other Conventional Medicines?

• Guselkumab Versus Other Medications: Corticosteroids act by suppressing the immune system and interfering with the inflammatory pathway. The body's overall immune response is reduced during corticosteroid therapy. Guselkumab belongs to the biologics (produced from living organisms or their components) group of drugs. These drugs interfere with the body's immune mechanism, which is responsible for the disease. Guselkumab particularly targets and blocks interleukin-23 (IL-23), which plays a crucial role in psoriasis pathology.

What Are the Side Effects of Guselkumab?

Below is a list of Guselkumab side effects:

Common Side Effects:

• Injection Site Reactions: Redness, swelling, or pain at the injection site.

• Upper Respiratory Infections: Symptoms like sore throat, nasal congestion, or coughing.

• Headache: A mild to moderate headache may occur.

• Stomach Issues: Nausea, diarrhea, or abdominal discomfort.

Less Common But Serious Side Effects:

• Allergic Reactions: Rash, itching, swelling (especially of the face or throat), or difficulty breathing.

• Infections: Increased risk of infections such as fungal or bacterial infections due to immune suppression.

• Immune System Complications: Worsening of autoimmune conditions in rare cases.

• Fatigue: Persistent tiredness or weakness.

1. Signs and Symptoms of Allergic Reactions:

• Redness at the site of injection.

• Difficulty breathing (dyspnea).

• Itching of the skin (urticaria).

• Elevated blood pressure or heart rate.

• Chest tightness (bronchospasm).

• Rashes on skin.

• Flushing.

2. Signs and Symptoms of Upper Respiratory Tract Infection:

• Throat pain.

• Runny nose.

• Sneezing.

• Congestion in the nose and sinus.

• Fever and fatigue.

• Coughing.

3. Symptoms of Tension-Type or Migraine Headache:

• Dull, aching head pain.

• A sensation of pressure around the head.

• Nauseous feeling or sensitivity to light in case of migraine.

4. Signs and Symptoms of Other Severe Infections (Tuberculosis or Gastroenteritis):

• Fever.

• Weight loss.

• Sweating.

• Cough.

• Dyspnea or difficulty in breathing.

• Pain and cramps in the muscle.

• Blood while coughing.

• Abdominal discomfort.

• Fatigue and malaise.

• Diarrhea.

5. Signs and Symptoms of Viral and Fungal Infections:

• Itchy skin with a ring-shaped rash.

• Hair loss.

• Skin pigmentation and peeling.

• Small red bumps or blisters on the skin (herpes infection).

• Ulcers and painful sores.

Get Regular Blood Tests:

According to clinical studies, Guselkumab elevates liver enzymes. Although the elevation in most of the study subjects was mild to moderate, it is always better to be on the safe side. Hence, it is essential to get regular blood tests to look for signs of liver damage.

Avoid Self-Medication If:

• Your healthcare provider does not train you or your caregiver for self-administration.

• If the physician has not evaluated a patient's condition before starting treatment under a particular program.

• Proceed with self-injection only after receiving proper training.

• Make sure your healthcare provider shows you how to inject yourself before trying it on yourself.

• The Instructions for use should always be read before using the prefilled Guselkumab syringe and whenever you obtain a refill.

• If you have questions about your medical condition or treatment, you should talk to your healthcare provider before injection.

What Are the Things to Tell Physicians Before They Prescribe Guselkumab?

• Inform your physician regarding the history of signs and symptoms of the condition, other medical conditions, current and past medications, laboratory test reports, etc.

• If there is an allergy to any medication, it should be priorly informed to avoid complications.

• Convey the history of infectious exposure to tuberculosis and history of latent or active tuberculosis if present.

• Discuss the immunization records before starting Guselkumab treatment.

• Any history of immune-compromised conditions like prolonged corticosteroid therapy, HIV (human immunodeficiency virus), and diabetes should be mentioned.

• If female patients are planning for pregnancy or breastfeeding babies, refrain from Guselkumab treatment.

• Get your liver and renal function tests to rule out other conditions.

• A prior intimation regarding major surgeries in the past or planned future surgeries is necessary.

• Lastly, explain all the medications with doses taken in the past.

Starting Guselkumab:

How to Take Guselkumab?

Guselkumab can be self-administered after following the physician's instructions. However, it should only be used under the guidance and prescription of an experienced doctor. After receiving self-administration training, patients can administer it on their own or with the help of a caretaker.

Things You Need:

• One Guselkumab prefilled syringe.

• One alcohol swab.

• One cotton ball or gauze pad.

• One adhesive bandage.

• One sharps disposal container.

Storage Instructions:

Guselkumab should be stored in a refrigerator at 36 degrees Fahrenheit to 46 degrees Fahrenheit (2 degrees Celsius to 8 degrees Celsius). A prefilled syringe of Guselkumab should not be frozen. Keep the medications and syringes away from children. To protect the solution from light and physical damage, store the Guselkumab prefilled syringe in its original carton box.

Instructions for Administering:

A. Prepare the Injection:

• Inspect the carton box for damage. Then, keep the prefilled syringe (along with the carton) on a flat surface at room temperature for 30 minutes.

• Do not use any other sources to warm the prefilled syringes.

• Check for the expiry date before administering the injection.

• If the carton box is perforated or damaged, call your physician or pharmacist for a refill, and do not administer until then.

B. Choose the Site for Infection:

• Recommended areas for injections include the front of the thighs and lower stomach area (lower abdomen, except for the 2-inch area around the belly button).

• Back of the upper arms if a caretaker is injecting the medication.

• Do not administer to that skin if the psoriasis site is tender, bruised, red, scaly, or hard.

C. Clean the Injection Site:

• Wash your hands with warm water and soap before administering.

• Wipe the injection site with a cotton swab dipped in alcohol and let it dry.

• After cleaning, do not dry the injection site by blowing, touching, or by a fan.

D. Inspect the Liquid:

• Before injecting, check the Guselkumab prefilled syringe liquid from the viewing window.

• The solution should look clear, light yellow, or may contain tiny clear or white particles.

• Air bubbles may also be present.

• If the injection is discolored, cloudy, or contains large particles, do not inject.

• Ask your physician or pharmacist for a refill if the solution is defective.

E. Remove the Needle Cover:

• Pull the needle cover straightly by holding the syringe by its body.

• During this, a drop of liquid may be seen at the tip.

• Guselkumab should be injected within five minutes after removing the cover.

• Avoid putting the needle cover back, as it can injure your fingers.

• Avoid touching the needle or any other surface.

• Call your physician or pharmacist if the syringe is dropped.

F. Needle Insertion and Positioning of the Fingers:

• The thumb, index, and middle fingers should be placed directly under the flange of the syringe.

• Do not touch the plunger or the area above the finger flange, as this can activate the needle safety device.

• Pinch the skin at the injection site using the other hand.

• The syringe should be positioned at 45 degrees to the skin.

• Do not inject into muscle; inject under the skin.

• The needle insertion should be a quick, dart-like motion.

G. Injecting the Solution:

• Grasp the body of the syringe with a free hand.

• Use the opposite hand's thumb to press the plunger until it stops.

• Release the finger pressure from the plunger slowly.

• While removing the needle, the safety guard will cover it and lock it.

H. Disposing of the Syringe:

• The used syringe should be disposed of in an FDA-approved sharps disposal container immediately after use.

• The prefilled syringes should not be thrown in the household trash.

• The used syringes should never be recycled or reused.

I. Inspecting the Injection Site:

• A small drop of blood or the solution may be present at the injection site.

• Apply direct pressure on the skin using a cotton ball or gauze to stop the bleeding.

• Avoid rubbing the site of injection.

• The injection site can be covered with a bandage if necessary.

The Recommended Diet for Patients on Guselkumab:

Unless the doctor advises otherwise, most patients can continue with their normal diet plan as they are not affected by the virus. Yet they should follow a nutritionally adequate and balanced diet. For instance, nuts, grains, fruits, and vegetables are advisable foods that have lots of iron and folic acid. Thirdly, omega fatty acids have health benefits in the fight against inflammation, and they can be incorporated into routine meals.

Staying On Guselkumab:

Tips to Stay on Track - The intensity of the symptoms can be reduced after several weeks of treatment. If the condition has not improved even after that, the physician may advise discontinuing the treatment. Reporting the symptoms of side effects after Guselkumab injection is important during the treatment. Follow the dosing schedule as instructed by the doctor.

Things to Keep In Mind -

1. In case of overdosage, monitor yourself for any symptoms of adverse reactions and contact your physician so that appropriate symptomatic treatment can be given immediately.

2. Contact your doctor to schedule the subsequent dosing in case you miss or forget to take the scheduled dose, as it may interfere with the recovery.

3. Regularly follow up with your physician and be aware of any adverse changes in your body.

For Doctors:

Indications:

• Currently, Guselkumab is approved for the treatment of psoriasis and psoriatic arthritis.

• Guselkumab acts by inhibiting the binding of specific cytokines and immune cells.

• Studies have shown clinical remission after Guselkumab treatment.

Contraindications:

Guselkumab should not be used in patients who have had an allergic reaction to the drug or any of its ingredients because such a reaction may happen again. It should be avoided in patients with active infections such as TB, which requires screening before beginning treatment, or other severe bacterial, viral, or fungal infections. Also, it is not for the immunocompromised population comprising cancer treatment, organ transplant, or HIV-positive individuals because Guselkumab weakens the immune system. Guselkumab should be used in pregnancy, particularly when the potential advantages justify the risks because there is little information about the safety of the medication for pregnant and breastfeeding women. In addition, the drug is contraindicated for use in patients receiving live viral vaccines because it can decrease vaccine effectiveness and risk of infection. The patients are encouraged to report any medical history to the health care practitioner to determine whether Guselkumab is safe for them.

Pharmacology:

Mechanism of Action:

Guselkumab is a human monoclonal antibody (IgG1λ). This molecule binds selectively to the p19 subunit of interleukin 23 (IL-23), which prevents its interaction with the IL-23 receptor. Guselkumab acts by inhibiting the release of interleukins that play a key role in the development of psoriasis. Interleukin 23 is one of the critical cytokines that play an essential immunological role in psoriasis.

Pharmacokinetics:

In healthy subjects and patients with psoriasis, Guselkumab exhibited linear pharmacokinetics after subcutaneous injection. The average steady-state through serum concentration of Guselkumab was approximately 1.2 mcg/mL after 100 mg of Guselkumab at weeks 0, 4, and every 8th week after that.

Pharmacodynamics:

Compared to the pretreatment levels, the serum levels of interleukins IL-17A, IL-17F, and IL-22 were reduced after Guselkumab therapy. This was evaluated based on the analysis of pharmacodynamic markers in psoriasis patients. However, researchers are yet to understand the relationship between these pharmacodynamic markers and the mechanisms by which Guselkumab exerts its clinical effects.

• Absorption: Approximately five and a half days after a subcutaneous injection of 100 mg Guselkumab, the serum concentration reached 8.09 ± 3.68 mcg/mL. Thus, a single subcutaneous injection of 100 mg of Guselkumab is estimated to have an absolute bioavailability of around 49 percent in healthy subjects. The apparent volume of distribution was 13.5 L in subjects with plaque-type psoriasis.

• Metabolism: Until now, it has not been possible to identify the exact enzyme responsible for Guselkumab's metabolism. However, as a human IgG monoclonal antibody, Guselkumab is expected to follow the same metabolic pathway as endogenous IgG. Therefore, it is thought to be degraded into small peptides and amino acids through catabolic pathways like other immunoglobulins.

• Elimination: In the subject with plaque-type psoriasis, the clearance rate was 0.516 L/day. Hence, in the subjects with plaque psoriasis across studies, the estimated average half-life of Guselkumab was assumed to be in the range of 15 to 18 days.

Warnings and Precautions:

1. Hypersensitivity and Infusion-Site Reactions: In this case, some of the patients might be highly sensitive to the ingredients in Guselkumab. The allergy can be as severe as anaphylactic shock. The reaction can also occur several days after the treatment. Stop the treatment immediately if there are any signs of hypersensitivity, such as dyspnea, urticaria, hypertension, or tachycardia. Start on antihistamine or epinephrine therapy in case of severe allergic reaction.

2. Risk of Developing Infections: If the patients have a pre-existing active infection, prescribing Guselkumab must be avoided. According to clinical trials, it has been reported that patients treated with Guselkumab are at increased risk of developing infections. Therefore, patients should also be instructed to seek immediate medical attention if they establish any sign of any illness or disease as an infection. In the event of serious infections, Guselkumab should be stopped until the infection is resolved fully. It is important to pre-screen the patients for tuberculosis due to further deterioration of their status in case of being positive for the disease.

3. Liver Injury: There is an increased incidence of Crohn’s disease in patients using Guselkumab to treat psoriatic arthritis. Therefore, when prescribing Guselkumab for psoriatic arthritis, it is always recommended to evaluate liver enzymes, and further treatment can be planned accordingly. 2.6 percent of the study subjects exhibited a mild to moderate increase in liver enzymes. If the enzymes alanine aminotransferase or aspartate aminotransferase are elevated, drug-induced liver damage should be suspected. Therefore, Guselkumab treatment should be discontinued until further evaluation.

4. Live and Oral Vaccines: All age-appropriate immunizations should be completed according to the standard immunization guidelines before starting Guselkumab. Although there is no evidence suggesting the interaction with live vaccines, evaluating the benefits and risks is always recommended. If the patient is receiving any live bacterial or viral vaccine, Guselkumab treatment should be stopped at least 12 weeks after the last dose. It can be continued after two weeks of the vaccination.

5. Risk of Cancer: Studies have not been conducted to evaluate the carcinogenic and mutagenic potential of Guselkumab.

Indications and Uses:

• Plaque Psoriasis: Guselkumab is indicated for the treatment of moderate to severe plaque-type psoriasis in patients who are eligible for systemic therapy.

• Psoriatic Arthritis: Guselkumab can either be used alone or combined with other drugs, such as Methotrexate, to treat psoriatic arthritis. It is helpful, especially in patients who show an inadequate response or are intolerant to other medications, such as disease-modifying antirheumatic drug (DMARD) therapy.

Dosage and Administration:

Subcutaneous Injection - 100 mg/mL in a prefilled single-dose syringe. Guselkumab injection is taken at a dose of 100 mg at week 0, week 4, and every 8th week after that.

Usage, Storage, and Training Instructions:

How Is Guselkumab Supplied?

• Guselkumab is supplied as a clear, colorless, or light yellow solution that contains small translucent particles.

• It is supplied in a carton box as a prefilled 100 mg/mL single-dose syringe.

How to Store and Handle Guselkumab Syringes?

• Guselkumab is supplied as a preservative-free sterile solution. Therefore, any unused portion of the solution should be discarded.

• The medicine should be stored in a refrigerator at 2 degrees to 8 degrees Celsius.

• Guselkumab should be stored in the original carton box until it is used.

• Protect the solution from light and physical damage.

• Do not freeze or shake the solution before using it.

Patient Counseling and Guidance Information:

• Patients should be advised to read the patient labeling information (medication guide and instructions for use) before starting treatment.

• New instructions might be included each time the prescription is renewed. Therefore, it is necessary to instruct the patients to follow them.

• Patients should also be aware of communicating any other manifestations of infections when he was receiving the treatment.

Drug Interactions:

1. With CYP450 Substrates - Clinical studies concluded that the drug interaction between Guselkumab and Midazolam, Warfarin, Omeprazole, Dextromethorphan, and caffeine was not clinically relevant. The results were variable due to the small sample size. However, patients receiving CYP450 substrates should be monitored for therapeutic effects and drug concentrations.

2. With Live Vaccines - Although no clinical relevance was found, live vaccines should be avoided in patients treated with Guselkumab.

3. With Immunosuppressive Therapy or Phototherapy - The interaction between Guselkumab and immunosuppressive drugs and phototherapeutic drugs has not been evaluated.

Use in Specific Populations:

1. Women of Childbearing Age - Fertile women should use an effective contraception method during and 12 weeks after Guselkumab treatment. The effect of Guselkumab on fertility has not been evaluated.

2. Pregnancy - No data is available to confirm the effects of Guselkumab in pregnant women. Animal study models have not indicated any harmful effects on pregnancy, fetal development, and location. However, IgG antibodies can cross the placental barrier. Therefore, Guselkumab might reach the fetus. However, it is always recommended to avoid Guselkumab during pregnancy and lactation.

3. Lactation - The excretion of Guselkumab in human milk is not known. Human IgG immunoglobulin is eliminated in breast milk after a few days of birth. Therefore, the risk of Guselkumab treatment during breastfeeding cannot be ruled out. It is always better to assess the risks and benefits of Guselkumab before starting treatment in breastfeeding women.

4. Geriatric Population - Little information is available on the effects of Guselkumab on patients over 65. According to available data, there was no difference in the overall effectiveness of Guselkumab in subjects over 65.

5. Pediatric Population - The efficacy and safety of Guselkumab have not been determined in children and young adults under 18 years of age.