Drug - Food Interactions

Nutritional Values Of Grapefruit

Grapefruit is a citrus fruit rich

in the following nutrients:

Vitamin C Vitamin A Vitamin B5 Potassium Folate Dietary Fiber

Nutritional Values Of Grapefruit

The nutritional values of

grapefruit varies with the

color (white, pink, or red).

Red and pink grapefruits

have a higher amount of

vitamin A. 

Medical Uses Of Grapefruit

Grapefruit is an excellent source of Vitamin C

which plays a role in the following:

Supporting the immune system Reduce severity of cold symptoms Reduce severity of inflammatory conditions Is beneficial to promoting cardiovascular

health

Pink and Red Grapefruit appears to have

anti-tumor activity.

Interactions Of Grapefruit With Medications

What Is Interaction?It is a situation in which a substance affects

the activity of the used medication by one

of the following ways:

The effect is increased. The effect is decreased. It produces a new effect.

How Does Grapefruit Interact

When we take a medicine

orally (by mouth), it has to

get into our blood stream to

do its action.

During this a significant portion of

the medicine is metabolized(changed)

to inactive ingredients by a certain

enzyme in either the intestine (first-pass metabolism) or the

liver,decreasing the amount of medication reaching the Blood.

How Does Grapefruit Interact

Grapefruit juice interferes with the

enzyme system responsible for

the metabolism of many

medications.

Therefore, the amount of

medication available in the body

will increase, possibly causing

toxic effects.

How Long Dose Grapefruit Interaction Persist Grapefruit juice can inhibit intestinal

enzyme concentration for 24 to 72

hours.

Therefore, separating the times of

medication administration and

grapefruit consumption is not a

reasonable solution.

It is important to note that

because of genetic differences,

the extent of interaction differs

from one patient to another.

Grapefruit and Statins

Statins are medications that lower cholesterol levelsby blocking the enzyme responsible for cholesterolsynthesis in the body.

Statins are the most widely prescribed cholesterollowering medications, since they affect every aspect inthe cholesterol panel in a favorable way.

Grapefruit and Statins

The components in grapefruit prevent the enzyme

system in the body from breaking down the statin

leading to its accumulation in the body.

Example:

Taking one tablet of lovastatin (Mevacor)

with a glass of grapefruit juice

is the same as taking 12 to 15 tablets

with a glass of water.

Problems Of Taking Grapefruit WithStatins

Problems associated with taking grapefruit with

stains are:

I. Liver damage

II. Kidney damage

III. Rhabdomyolisis

This rare but potentially life-threatening

Side effect. The most common symptoms are: Severe muscle aching throughout the

entire body Muscle weakness Dark or cola-colored urine

The higher the dose of statins, the higher the risk of

Rhabdomyolysis.

Are All Statins Affected

So far, the only statins significantly affected by this interaction

are: Atorvastatin (Lipitor®) Lovastatin (Mevacor®) Simvastatin (Zocor®)

Other statins do not seem to demonstrate

the same, profound effect with grapefruit

as seen with the other statins. These would include: Rosuvastatin (Crestor®) Pravastatin (Pravachol ®) Fluvastatin (Lescol ®)

This may be due to the fact that these statins are not broken

down by the same enzymes.

Grapefruit And Antihistamines

Antihistamines are medications used to treat allergies.

Interaction of grapefruit with antihistamines

like terfenadine or astemizole leads to fatal

cardiac arrhythmias (Irregular heart beat).

There are other non-sedating antihistamines which do not

interact with grapefruit juice. (e.g., loratidine (Claritin ®)

cetirizine (Zyrtec ®).

Grapefruit and Calcium Channel Blockers

Calcium Channel Blockers are medications that prevent

calcium from entering cells of the heart and blood vessel

walls, resulting in lowering blood pressure.

Grapefruit juice is likely to increase the levels of Calcium

Channel Blockers in the blood causing the following: Low blood pressure Increased heart rate Dizziness Flushing Headache

Other Medications Affected ByGrapefruit

Grapefruit interacts with a wide range of medications such as: Psychiatric Medications

Immune Suppressants Pain Medications (Methadone) Impotence drugs Intestinal Medications (Cisapride)

Grapefruit juice inhibits the body's ability to absorb some

drugs like:  Losartan (for lowering blood pressure) Digoxin (for treating congestive heart failure)

Grapefruit Forms

Will all forms of grapefruit cause

interaction with medications

It has been shown that both

grapefruit sections and grapefruit

extract has the same effect on

medications as grapefruit juice.

Grapefruit And Citrus Fruits

There are citrus fruits which

can cause the same drug

interaction as grapefruit

such as:

Seville Orange (found in marmalade and jams)

Pomelos Tangelos

What Are Pomelos

Pomelo - Also called the "Chinese

grapefruit", it's native to southeast

Asia.

It is, in fact, an ancestor of the

grapefruit.

The grapefruit was formed from

crossing between the pomelo and

the orange to give us the modern

grapefruit varieties we know

today.

What Are Tangelos

The tangelo is a hybrid

between the pomelo and the

tangerine.

The fruit is known in some

countries as "sweetie”.

Summary

A number of medications

are reported to have

interactions with grapefruit.

Before taking any

medication with grapefruit

you have to make sure that

there is no interaction.

There are several other fruit

juices available as a

substitute to grapefruit juice.