Imiquimod (Topical)

Overview

Imiquimod is a prescription-only topical cream which modifies the response of the immune system. It is often used to treat genital warts but is also effective in treating certain skin cancers, either as a second-line treatment to surgery or as an alternative when surgery is not recommended, or if surgery could otherwise cause unwanted scarring.

This medication was first discovered in 1997 by chemists at 3M's pharmaceutical division, as part of a program developed to find inhibitors of the replication method of the herpes simplex virus. It was approved by the FDA in the same year and is often marketed under the name Aldara in the United States. Evidence suggests that Imiquimod activates Lanerghans cells when it is applied to the skin. These cells migrate to the local lymph nodes, activating the adaptive immune system. It also activates other cell types, such as macrophages, B-lymphocytes and natural killer cells, making it effective in treating many types of skin disorder.

Imiquimod is also used to treat other skin conditions which, if left untreated, can develop into squamous skin cancer. It is typically used to treat superficial basal skin cancers measuring no larger than 2cm in width on the neck, arms, legs or chest – however, it may not be suitable for basal skin cancers measuring more than 2cm, or for a specific type of basal skin cancer called nodular BCC.

Type Of Medicine

  • Immune response modifier

Conditions Treated

  • Basal skin cancer
  • Actinic keratosis
  • Genital warts
  • Melanoma

Side Effects

Along with the desired effects, Imiquimod can also cause some unwanted side effects. The most common side effects reported by patients undergoing treatment with this medication include the following:

  • Blisters on the skin
  • Body pains and aches
  • Coughing
  • Chills
  • Congestion in the ears
  • Difficulty breathing
  • Itching in the genital area
  • Itching in other skin areas
  • Voice loss
  • Scabs and/or open sores on the skin
  • Tenderness or pain around the cheekbones and eyes
  • Scaly skin
  • Severe redness of the skin
  • Shortness of breath
  • Sore throat
  • Sneezing
  • Runny or stuffy nose
  • Unusual weakness or tiredness
  • Tightness of the chest
  • Wheezing

As the patient continues to apply Imiquimod topical cream as prescribed by a qualified physician, many (if not all) of the previously mentioned side effects and symptoms should begin to lessen. If side effects appear to worsen or persist over a prolonged period, the patient is advised to consult their doctor or healthcare provider as soon as possible. In many instances, a doctor or pharmacist may be able to advise on ways to alleviate side effects using over the counter remedies or other prescription drugs.

Generally, most patients will only experience minimal side effects which using Imiquimod topical cream, if they observe any effects whatsoever. Imiquimod is designed to alleviate many of the previously mentioned symptoms, and most doctors agree that the benefits of treating skin cancer with this topical cream far outweigh the risks of experiencing the temporary discomfort of some side effects.

Other side effects which are experienced less frequently, albeit often enough to warrant mentioning, include the following:

  • Pain in the bladder
  • Abdominal or stomach pain
  • Cloudy or bloody urine
  • Severe pain in the toe joints
  • Ankle or knee pain
  • Blurry vision
  • Chest pain
  • Painful burning sensation when urinating
  • Fainting
  • Dizziness
  • Irregular or fast heartbeat
  • An increased urge to urinate
  • Pain in the lower back or side
  • Hoarseness of the voice/throat
  • Lumps in the stomach or abdomen
  • Persistent non-healing sores
  • Pounding in the ears
  • Pink growths on the skin
  • Nervousness or anxiety
  • Severe headache
  • Shiny bumps on the skin
  • Painful, tender or swollen lymph glands in the armpit, groin or neck
  • Waxy, yellow or white scar-like areas of the skin

Other side effects have been reported, although these occur so rarely that their level of incidence is unknown. These can include:

  • Weight gain
  • Blue fingernails and lips
  • Weakness in the legs or arms, or on one side of the body
  • Coughing which sometimes produces a frothy, pink sputum
  • Temporary blindness
  • Dilated veins in the neck
  • Swelling of the feet, lower legs, fingers or face
  • Extreme tiredness/fatigue
  • Sweating
  • Pounding heartbeat
  • Suicidal thoughts
  • Nausea
  • Vomiting
  • Sudden, severe inability to speak
  • Slurred speech
  • Pain in the arms, jaw, shoulders or neck

It is worth noting that Imiquimod can affect the psychology of the patient. He or she could potentially experience anxiety, nervousness, and even suicidal thoughts. Because this risk exists, great care should be taken when prescribing this medication to patients with a history of mental health conditions (such as depression, bipolar disorder or schizophrenia).

Imiquimod can also cause vision problems. Patients are therefore advised against driving or operating heavy machinery until it has been observed that these side effects do not occur or do not cause any issues which could put the patient or other road users at risk.

Not all side effects may have been reported. If the patient thinks they may have experienced a side effect which has not been listed by the manufacturer, they are advised to consult their doctor and report their findings to the FDA.

Dosage

As with all medicines, it is imperative that the patient only applies Imiquimod topical cream as prescribed by a qualified physician. This means that patients should avoid using any more of this medication than advised, either in terms of frequency or dose size. In addition to this, the patient should be prepared to stop using Imiquimod when told to by a doctor, even if they still have a supply of the medicine remaining.

Imiquimod is available in various concentrations, and the concentration of a prescribed cream may vary dependent on the condition being treated. The frequency of treatment and amount of cream required may also vary dependent on the strength of the cream.

Typical adult dose for keratosis:

For patients being treated with a 2.75% or 3.75% cream, Imiquimod should be applied in a thin film once a day to the affected area. It should be rubbed in over the entire treatment area until it is no longer visible. Up to two pump actuations or packets of Imiquimod should be applied per application. Doctors recommend that Imiquimod is applied before bedtime and allowed to remain on the skin for approximately 8 hours, at which point the affected area should be washed with water and a mild soap to remove any excess cream. This treatment should continue daily for a two-week period, followed by a 2-week rest period where no Imiquimod is applied.

Patients who are undergoing treatment with a 5% strength cream should apply the cream to the affected area, twice a week for a period of up to 16 weeks (for example, once on a Monday and once on a Thursday). As with the weaker concentrations of the cream, Imiquimod 5% should be rubbed in until it is no longer visible. No more than one packet or pump actuation of Imiquimod 5% should be applied to the treatment area per application. Like the weaker cream, it should be applied at bedtime and washed away after approximately 8 hours with mild soap and water.

Typical adult dose for genital warts (Condylomata Acuminata):

Imiquimod 3.5% cream is generally prescribed for the treatment of genital warts. It should be applied in a thin layer, once per day, to the area affected by genital or perianal warts until the condition clears. If warts have not cleared after 8 weeks, the patient should discontinue use and consult their doctor or healthcare provider.

Up to one packet or pump actuation of Imiquimod 3.5% is suitable for the treatment of genital warts. It should be applied at bedtime and left on the skin until the morning when the affected area should be cleaned with water and mild soap. If required, non-occlusive dressings (such as cotton underwear or cotton gauze) can be employed for the management of skin reactions.

For particularly virulent cases of genital warts, a doctor may prescribe Imiquimod 5% cream, which should be applied before bedtime, up to three times a week (such as Monday, Wednesday and Friday).

Typical adult dose for basal cell carcinoma:

A doctor will generally prescribe no less than Imiquimod 5% cream for BCC. It should only be prescribed after a biopsy has confirmed the presence of a superficial basal cell carcinoma. Imiquimod should be applied for BBC 5 times per week, for a period of 6 weeks. It should be applied before bedtime and left on the skin for approximately 8 hours, before being removed with water and a mild soap. The treatment area should extend to a 1cm margin around the tumor. A sufficient amount of the cream should be used to cover the treatment area and rubbed in until it is no longer visible.

Imiquimod should only be used for basal skin carcinoma when surgical methods are medically inappropriate or less appropriate, and that patient follow-up can be assured.

While the manufacturer of Imiquimod provides general dose instructions, it must be reiterated that these are merely guidelines which can be altered at the discretion of the patient's doctor. When determining the appropriate dose size, a doctor will take the height, weight, age and condition of the patient into account, among other factors.

There is no recommended Imiquimod dose size for children under the age of 12. Instead, the manufacturer leaves the pediatric dose size and frequency up to the administering physician.

Patients are advised not to take double doses of this medicine. If the patient misses a dose, they should simply omit the missed dose and take the next planned dose as normal, before continuing with the dose schedule as planned. This is because taking a double dose could lead to overdose.

If the patient experiences any symptoms of overdose (confusion, dizziness, light-headedness or faintness) they may require immediate medical attention. In this instance, the patient or their caregiver should contact their local poison control center on 1800-222-1222 or emergency services on 911. Alternatively, the patient may make their own way to the nearest ER, provided it is in close enough proximity.

Interactions

All medications have the potential to interact with other drugs or chemicals within the body, and these interactions can cause changes in the effects of one or more medications. In some cases, an interaction can cause a medication to become ineffective in treating the condition it was prescribed to combat. In other cases, interactions can cause dangerous or even fatal side effects in the patient. Because these risks exist, it is important for the patient to keep a full, detailed list of all medicines they are currently taking. This includes over the counter remedies, complementary medicines, vitamins and herbal supplements as well as prescribed drugs.

There are no documented reactions between Imiquimod and any other drugs, although this does not mean that no interactions exist. Patients who believe they may have experienced an interaction between Imiquimod and other drugs should consult their doctor and report their experience to the FDA.

Warnings

Imiquimod is for topical use only. It is not designed for ophthalmic, intravaginal, oral or intra-anal use. Patients should avoid application around the eyes, lips and/or nostrils. Medical advice should be sought if it is ingested in any of these ways.

Patients are advised to wash their hands before and after Imiquimod use, as it could be damaging to skin if it left in contact for prolonged periods. The use of excessive amounts of Imiquimod cream should be avoided. To ensure the correct amount of cream is dispensed, the pump should be primed by depressing the actuator multiple times until the cream is released.

Some patients may experience local skin reactions. In some instances, a doctor may recommend a rest period of several days if the patient experiences discomfort or severe reactions. However, treatment cycles should not be extended due to these rest periods or missed doses.

The full treatment course should continue, even if actinic keratoses appear to have disappeared fully. Doctors should carefully re-evaluate patients to ensure lesions have responded adequately to treatment.

Imiquimod should not be used on areas of wounded, burned or broken skin. The patient is advised to wait until these conditions have healed fully before commencing treatment with Imiquimod topical cream.

If the patient is using Imiquimod to treat genital warts, they are advised to try and keep the cream from meeting the sensitive inner layers of vaginal tissue or the inner foreskin, as this can result in swelling, irritation and painful urination.

Patients undergoing treatment with Imiquimod topical cream should avoid direct exposure to sunlight, UV light or tanning beds. This is because Imiquimod can make the patient sunburn much more easily. Patients are therefore advised to wear protective clothing and to use sunscreen with an SPF factor of 30 or higher when intending on being outdoors for prolonged periods.

Although Imiquimod topical cream can help alleviate symptoms of genital warts, it is not a cure for the condition. It will therefore not be sufficient in stopping the condition from spreading (either on the patient or others) during vaginal, anal or oral sex.

Before using Imiquimod, patients should advise their doctor or healthcare provider if any of the following conditions apply:

  • They have a weakened immune system
  • They have an autoimmune disorder
  • They have HIV or AIDS
  • They have a graft-versus-host disease
  • They have recently received a blood cord transplant
  • They have recently received a bone marrow transplant

Patients who are treating the genital or rectal area with Imiquimod topical cream are advised to avoid all sexual activity while the medicine is in contact with the skin. Sex with condoms is not advised, as Imiquimod topical cream contains ingredients which can weaken the rubber condoms are manufactured from, increasing the risk of them breaking.

Imiquimod can potentially cause adverse fetal effects. Pregnant mothers are therefore advised to avoid using this medicine unless the benefits drastically outweigh the risks. It is unknown whether this medication is excreted into human breastmilk, although nursing mothers are advised to either cease breastfeeding while using Imiquimod or avoid using Imiquimod altogether.

Storage

Imiquimod should be stored at room temperature, away from sources of light, moisture and heat. It is therefore not suitable for storage in a bathroom. If possible, it should be kept in a locked, dedicated medicine cabinet out of the reach of children and/or pets. Packets containing a pump should be stored in an upright position. Packets should also be kept unopened until the patient is ready to use it.

To dispose of unwanted, unused or expired Imiquimod, the patient is advised to follow FDA guidelines and ensure they are disposing of this medicine in accordance with state law. Many pharmacies offer “takeback” programs where they will exchange or otherwise safely dispose of expired and unwanted medicines. Patients are advised to take advantage of these programs.

Summary

While Imiquimod topical cream is a greatly beneficial medication, it can also pose a risk to patients who do not communicate effectively with their physicians. It is a treatment designed to alleviate genital warts and is also useful in treating various forms of skin cancer by causing the immune system to modify its response to certain cell types. However, it can also cause nausea, dizziness, faintness and other detrimental side effects which can impair the daily functioning of the patient and even create perilous situations if the correct precautions are not taken. Because of this, it is important for the patient to be upfront and honest about their medical history, including any hereditary illnesses in the family.

When taken correctly, Imiquimod can relieve the symptoms of serious basal skin cancers which may have otherwise been untreatable with surgery. In some cases, this means removing potentially fatal melanomas and saving the cancer from growing or spreading to other areas of the body. To achieve this, patient and doctor need to work together to determine the most appropriate dosage and frequency of use.