Drugs and Kidney Problems

Kidney damage due to different drugs is common.

Why is the kidney more vulnerable to drug toxicity compared to other organs of the body?

Two most important causes of damage to kidney due to drugs are:

Drug excretion by kidney: The kidney is a major organ involved in the removal of drugs and its metabolites. During the process of drug removal some drugs or its metabolites can damage the kidney.

High blood flow to kidney: Every minute 20% of total blood pumped by the heart (1200 ml blood) enters both kidneys for purification. Among all organs of the body, the kidney receives the highest amount of blood per kilogram weight of the organ. Because of the rich blood supply, harmful drugs and substances are delivered to the kidney in a large amount and in a short time. This can damage the kidney.

Principal drugs that damage the kidneys

Pain killers

For body ache, headache, joint pain and fever, various over the counter (OTC) medicines are available and these drugs are taken freely without doctor’s prescription. These drugs are principally responsible for kidney damage.

What are NSAIDs? Which drugs belong to this group?

Non Steroidal Anti-Inflammatory Drugs (NSAIDs) are common medications used to reduce pain, fever and inflammation. These drugs include aspirin, diclofenac, ibuprofen, indomethacin, ketoprofen, meloxicam, mefenamic acid, nimesulide, naproxen etc.

Do NSAIDs cause damage to kidneys?

NSAIDs are generally safe provided they are taken in correct doses under the supervision of a doctor. But it is important to remember that NSAIDs rank second to aminoglycosides as the most common cause of drug induced kidney damage.

When can NSAIDs damage kidneys?

Risk of NSAID induced kidney damage is high in cases of:

• Prolonged NSAID use taken in high dosages without supervision of a doctor.
• Prolonged use of a combination drug in a single pill (e.g. APC which contains aspirin, phenacetin and caffeine).
• NSAID use in the elderly, those with kidney failure, diabetes or dehydration.

Which pain killer is safe for kidney failure patients?

Paracetamol (acetaminophen) is a safer drug for pain compared to NSAIDs.

Many heart patients are prescribed lifelong aspirin. Can this damage the kidney?

Since a low dose of aspirin is advised for cardiac patients, it is safe.

Is kidney damage caused by NSAIDs reversible?

Yes and No.

Yes. When acute kidney damage is due to short term use of NSAIDs, it is usually reversible by stopping NSAID drugs and proper treatment.

No. Many elderly patients with joint pain need NSAIDs for a long period. When taken continuously in large doses for a long period (years) NSAID use can lead to slow and progressive kidney damage. This type of kidney damage is irreversible. Elderly patients, who need large doses of NSAIDs for a very long period, should take these medications under the guidance and supervision of a physician.

How does one diagnose slow but progressive kidney damage due to long term NSAIDs in the early stage?

Appearance of protein in urine is the first and only clue of kidney damage due to NSAIDs. When kidney function worsens creatinine level in blood rises.

Simple measures to prevent kidney damage due to pain killers are:

• Avoid the use of NSAIDs in high risk persons.
• Avoid indiscriminate use of pain killers or OTC pain relievers.
• When NSAIDs are necessary for a long period, they should be taken strictly under the doctor’s supervision.
• Limit dose and duration of treatment with NSAIDs.
• Avoid a combination of mixture of pain killers for a long period.
• Drink plenty of fluid daily. Adequate hydration is important to maintain proper blood supply to kidney and to avoid damage to kidney.

Aminoglycosides

Aminoglycosides are a group of antibiotics frequently used in practice and a common cause of kidney damage. Kidney damage occurs usually 7 - 10 days after the initiation of therapy. Diagnosis of this problem is often missed because volume of urine is unaltered.

The risk of aminoglycosides induced kidney damage is high in the elderly, dehydration, pre-existing kidney disease, potassium and magnesium deficiency, administration of large doses for prolonged periods, combination therapy with other drugs which can damage the kidney, sepsis, liver disease and congestive heart failure.

How does one prevent kidney damage due to aminoglycosides?

Measures to prevent the kidney damage due to aminoglycosides are:

• Cautious use of aminoglycosides in high risk persons. Correction or removal of the risk factors.
• Once-daily administration of aminoglycosides instead of divided dosage.
• Use of optimum dose and duration of aminoglycosides therapy.
• Dose modification in the presence of pre-existing kidney damage.
• Serial monitoring of serum creatinine every other day for early detection of kidney damage.

Radiocontrast injections

Radiographic contrast media (X-ray dyes) induced kidney damage is a common cause of acute kidney failure in hospitalized patients, and is usually reversible. The risk of contrast induced kidney damage is high in the presence of diabetes, dehydration, heart failure, pre-existing kidney damage, advanced age and concurrent use of drugs that can damage the kidney.

Different measures can prevent contrast induced kidney damage. Important measures are use of smallest dose of contrast, use of nonionic contrast agents, maintaining adequate hydration with IV fluids, and administration of sodium bicarbonate and acetylcysteine.

Other drugs

Other common drugs that can damage kidneys are certain antibiotics, anticancer therapy, antituberculosis drugs etc.

Other medicines

• The popular belief that all natural medicines (Aurvedic medicines, Chinese herbs etc.) and dietary supplements are harmless is wrong.
• Certain medicines of these groups contain heavy metals and toxic substances which can cause damage to the kidney.
• Use of certain medicines of these groups can be dangerous in patients with kidney failure.
• Certain drugs with high potassium content can be lethal in kidney failure.

Source: Kidney Education Foundation