How to deal with common adverse reactions to targeted drugs?

Compared to traditional chemotherapy, targeted drugs not only improve efficacy, but also have significantly fewer side effects. However, there are still some adverse effects during treatment that require your attention and management.

Skin reactions

Common skin reactions include rash, nail fungus and nail fracture, dry skin, and hair changes. They usually appear within 2 weeks of drug administration and are most often seen on the scalp, face, neck, and chest and back.

When caring for the skin, it is important to moisturize the skin by applying topical medications on a daily basis to keep the skin moisturized; wear a mask and scarf to protect the facial skin from dryness. If you have dry keratoconjunctivitis, you should also wear glasses to block light and wind, use eye ointment at night to keep your cornea moist, and go to the hospital for regular checkups.

The rash can be classified as mild, moderate, or severe:

Mild rash: (papular lesions or erythema, usually on the head and face) covering less than 10% of the body surface area should be avoided with bright light exposure and skin hygiene. Avoid scratching the skin, do not use alkaline soap, and apply moisturizer or vitamin E ointment if the skin is dry or itchy.

Moderate rash: (papular lesions with erythema, usually on the head, face, and upper trunk) covering 10% to 30% of the body surface area should be treated with hydrocortisone or clindamycin on top of mild rash control.

Severe rash: (widespread severe blistering or papular lesions covering >30% of the body surface area) should be temporarily discontinued under medical supervision and localized with mupirocin ointment and considered for resumption only after recovery to a mild rash.

Diarrhea

First, pay attention to dietary hygiene and avoid irritating foods. According to the severity compared to the pre-treatment level, it can be classified as follows, and you can refer to the control treatment:

Mild diarrhea (increase in stool frequency <4 times per day compared to pre-treatment): you can take oral montelukast (trade name "Simethicone") to stop the diarrhea;

Mild diarrhea (increase in stool frequency <4 times per day compared to pre-treatment)

Moderate diarrhea (increase in stools 4-6 times per day compared to pre-treatment): Loperamide hydrochloride (“Emmenthal”) can be given orally and the diarrhea will be controlled after a short period of treatment.

Severe diarrhea (increase in stool frequency ≥7 times per day compared to pre-treatment; or stool incontinence requiring hospitalization): this should be discontinued for observation, fluid replacement and correction of electrolyte disturbances, and prompt medical attention to actively examine the possibility of pseudomembranous enterocolitis.

Nausea and vomiting

For mild to moderate nausea and vomiting, consider metoclopramide, dexamethasone, and diphenhydramine alone or in combination to improve antiemetic effects. Once-daily chlorpromazine therapy, if necessary, can also be effective in controlling it.

In severe cases, 5-hydroxytryptamine receptor antagonist drugs, such as granisetron, are required.

If nausea and vomiting are severe enough that: oral intake of energy and water is inadequate; nasal feeding, total parenteral nutrition (nutrition infused into the body via intravenous infusion), or hospitalization is required, then the target drug should be discontinued for observation and fluid replacement and increased electrolyte intake should be instituted.

Oral mucositis, oral ulcers

During the drug administration, the oral mucosa should be observed, oral hygiene should be maintained, less frequent meals should be eaten, and spicy, too hard, and too hot foods should be avoided. Gargling with saline (0.9% sodium chloride solution) or mouthwash after meals can prevent mouth ulcers.

If a mouth ulcer occurs, it can be healed in 2 to 3 days by applying Yunnan Baiyao externally to the wound. If the pain is severe, topical medications such as 20% lidocaine and aluminum thioglycollate can be added.

Abnormal liver function

Liver function should be checked before taking the drug and rechecked every 2 to 4 weeks while on the drug. If abnormally elevated transaminases are found, you should seek medical attention and use liver protection drugs under the guidance of your doctor.

When there is a degree 3 elevation in transaminases (AST or ALT greater than 5 times the normal value), targeted medications should be suspended and liver protection therapy should be administered, and the medication should be considered to be resumed when it returns to degree 1.

In addition, hepatitis virus carriers need continuous antiviral therapy to avoid fulminant hepatitis.

Special types of adverse reactions

Crizotinib (Crizotinib) may cause visual abnormalities and lower extremity edema:

1. Visual abnormalities

More often manifested as flashes of light, double vision, or impaired bright adaptation to light. This side effect occurs most often within 2 weeks of dosing and is usually mild, usually returning to normal within a short period of time, and usually does not require dose reduction or discontinuation.

While taking the medication, you are cautioned to drive or use machines in low light environments (tunnels, at night). If decreased visual acuity occurs, to rule out other causes (such as optic nerve papillary edema or retinal metastases), an eye exam should be performed, the drug should be suspended, and the dose of crizotinib should be adjusted pending recovery. If the initial dose is 250 mg twice daily, then a reduction to 200 mg in the morning and 200 mg in the evening may be considered.

2. Lower extremity edema

Moderate physical activity, increased water intake, and a low-salt diet may improve lower extremity edema.

Diuretics increase the risk of electrolyte disturbances and cardiovascular events, so long-term use is not recommended. Severe cases should wear compression stockings and follow dietary recommendations.