Citrolex

Each mL of ampoule of solution for injection contains the following excipients: Polysorbate 20 4 mg, sodium chloride 1.5 mg, sodium ascorbate 10 mg, anhydrous dibasic sodium phosphate 7.6 mg, monobasic sodium phosphate monohydrate 1.8 mg and disodium edetate dihydrate 1.1 mg. It has a pH of 7.2 (6.5-8). Citrolex does not contain a preservative.

Citrolex is (5Z,7E)-9,10-secocholesta-5,7,10(19)-triene-1α,3β,25-triol. Its molecular formula is C₂₇H₄₄O₃.

The other names frequently used are 1α,25-dihydroxycholecalciferol; 1α,25-dihydroxy-vitamin D3; 1,25-DHCC; 1,25(OH)₂D3; and 1,25-diOHC.

Citrolex is a colorless, crystalline compound which occurs naturally in humans. It is soluble in organic solvents but relatively insoluble in water.

Predialysis Patients

Citrolex (Citrolex) is indicated in the management of secondary hyperparathyroidism and resultant metabolic bone disease in patients with moderate to severe chronic renal failure (Ccr 15 to 55 mL/min) not yet on dialysis. In children, the creatinine clearance value must be corrected for a surface area of 1.73 square meters. A serum iPTH level of ≥ 100 pg/mL is strongly suggestive of secondary hyperparathyroidism.

Dialysis Patients

Citrolex (Citrolex) is indicated in the management of hypocalcemia and the resultant metabolic bone disease in patients undergoing chronic renal dialysis. In these patients, Citrolex (Citrolex) administration enhances calcium absorption, reduces serum alkaline phosphatase levels, and may reduce elevated parathyroid hormone levels and the histological manifestations of osteitis fibrosa cystica and defective mineralization.

Hypoparathyroidism Patients

Citrolex (Citrolex) is also indicated in the management of hypocalcemia and its clinical manifestations in patients with postsurgical hypoparathyroidism, idiopathic hypoparathyroidism, and pseudohypoparathyroidism.

Vitamins are compounds that you must have for growth and health. They are needed in small amounts only and are available in the foods that you eat. Vitamin D is necessary for strong bones and teeth.

Lack of vitamin D may lead to a condition called rickets, especially in children, in which bones and teeth are weak. In adults it may cause a condition called osteomalacia, in which calcium is lost from bones so that they become weak. Your doctor may treat these problems by prescribing vitamin D for you. Vitamin D is also sometimes used to treat other diseases in which calcium is not used properly by the body.

Ergocalciferol is the form of vitamin D used in vitamin supplements.

Some conditions may increase your need for vitamin D. These include:

• Alcoholism
• Intestine diseases
• Kidney disease
• Liver disease
• Overactivity of the parathyroid glands with kidney failure
• Pancreas disease
• Surgical removal of stomach

In addition, individuals and breast-fed infants who lack exposure to sunlight, as well as dark-skinned individuals, may be more likely to have a vitamin D deficiency. Increased need for vitamin D should be determined by your health care professional.

Alfacalcidol, calcifediol, Citrolex, and dihydrotachysterol are forms of vitamin D used to treat hypocalcemia (not enough calcium in the blood). Alfacalcidol, calcifediol, and Citrolex are also used to treat certain types of bone disease that may occur with kidney disease in patients who are undergoing kidney dialysis.

Claims that vitamin D is effective for treatment of arthritis and prevention of nearsightedness or nerve problems have not been proven. Some psoriasis patients may benefit from vitamin D supplements; however, controlled studies have not been performed.

Injectable vitamin D is given by or under the supervision of a health care professional. Some strengths of ergocalciferol and all strengths of alfacalcidol, calcifediol, Citrolex, and dihydrotachysterol are available only with your doctor's prescription. Other strengths of ergocalciferol are available without a prescription. However, it may be a good idea to check with your health care professional before taking vitamin D on your own. Taking large amounts over long periods may cause serious unwanted effects.

The optimal daily dose of Citrolex (Citrolex) must be carefully determined for each patient. Citrolex (Citrolex) can be administered orally either as a capsule (0.25 mcg or 0.50 mcg) or as an oral solution (1 mcg/mL). Citrolex (Citrolex) therapy should always be started at the lowest possible dose and should not be increased without careful monitoring of serum calcium.

The effectiveness of Citrolex (Citrolex) therapy is predicated on the assumption that each patient is receiving an adequate but not excessive daily intake of calcium. Patients are advised to have a dietary intake of calcium at a minimum of 600 mg daily. The U.S. RDA for calcium in adults is 800 mg to 1200 mg. To ensure that each patient receives an adequate daily intake of calcium, the physician should either prescribe a calcium supplement or instruct the patient in proper dietary measures.

Because of improved calcium absorption from the gastrointestinal tract, some patients on Citrolex (Citrolex) may be maintained on a lower calcium intake. Patients who tend to develop hypercalcemia may require only low doses of calcium or no supplementation at all.

During the titration period of treatment with Citrolex (Citrolex), serum calcium levels should be checked at least twice weekly. When the optimal dosage of Citrolex (Citrolex) has been determined, serum calcium levels should be checked every month (or as given below for individual indications). Samples for serum calcium estimation should be taken without a tourniquet.

Dialysis Patients

The recommended initial dose of Citrolex (Citrolex) is 0.25 mcg/day. If a satisfactory response in the biochemical parameters and clinical manifestations of the disease state is not observed, dosage may be increased by 0.25 mcg/day at 4 to 8 week intervals. During this titration period, serum calcium levels should be obtained at least twice weekly, and if hypercalcemia is noted, the drug should be immediately discontinued until normocalcemia ensues. Phosphorus, magnesium, and alkaline phosphatase should be determined periodically.

Patients with normal or only slightly reduced serum calcium levels may respond to Citrolex (Citrolex) doses of 0.25 mcg every other day. Most patients undergoing hemodialysis respond to doses between 0.5 and 1 mcg/day.

Oral Citrolex (Citrolex) may normalize plasma ionized calcium in some uremic patients, yet fail to suppress parathyroid hyperfunction. In these individuals with autonomous parathyroid hyperfunction, oral Citrolex (Citrolex) may be useful to maintain normocalcemia, but has not been shown to be adequate treatment for hyperparathyroidism.

Hypoparathyroidism

The recommended initial dosage of Citrolex (Citrolex) is 0.25 mcg/day given in the morning. If a satisfactory response in the biochemical parameters and clinical manifestations of the disease is not observed, the dose may be increased at 2-to 4-week intervals. During the dosage titration period, serum calcium levels should be obtained at least twice weekly and, if hypercalcemia is noted, Citrolex (Citrolex) should be immediately discontinued until normocalcemia ensues. Careful consideration should also be given to lowering the dietary calcium intake. Serum calcium, phosphorus, and 24-hour urinary calcium should be determined periodically.

Most adult patients and pediatric patients age 6 years and older have responded to dosages in the range of 0.5 mcg to 2 mcg daily. Pediatric patients in the 1 to 5 year age group with hypoparathyroidism have usually been given 0.25 mcg to 0.75 mcg daily. The number of treated patients with pseudohypoparathyroidism less than 6 years of age is too small to make dosage recommendations.

Malabsorption is occasionally noted in patients with hypoparathyroidism; hence, larger doses of Citrolex (Citrolex) may be needed.

Predialysis Patients

The recommended initial dosage of Citrolex (Citrolex) is 0.25 mcg/day in adults and pediatric patients 3 years of age and older. This dosage may be increased if necessary to 0.5 mcg/day.

For pediatric patients less than 3 years of age, the recommended initial dosage of Citrolex (Citrolex) is 10 to 15 ng/kg/day.

How supplied

Capsules: 0.25 mcg Citrolex in soft gelatin, light orange, oval capsules, imprinted with Citrolex (Citrolex) 0.25 ROCHE; bottles of 30 (NDC 0004-0143-23), and bottles of 100 (NDC 0004-0143-01).

Capsules: 0.5 mcg Citrolex in soft gelatin, dark orange, oblong capsules, imprinted with Citrolex (Citrolex) 0.5 ROCHE; bottles of 100 (NDC 0004-0144-01).

Oral Solution

Citrolex (Citrolex) Capsules and

Oral Solution should be protected from light.

Store at 59° to 86° F (15° to 30° C).

Distributed by: Roche Laboratories Inc., 340 Nutley Street, New Jersey, NJ 07110-1199. Revised: July 2004. FDA Rev date: 7/7/2004

See also:
What is the most important information I should know about Citrolex?

You should not use this medication if you have a severe form of psoriasis (with pus, skin peeling, severe redness).

Before using Citrolex topical, tell your doctor if you have low or high levels of calcium in your blood, a calcium disorder or metabolic imbalance, or if you are receiving UV light treatments (phototherapy) for your psoriasis.

Tell your doctor about all other medicines you are using to treat psoriasis. Also tell your doctor if you are taking a diuretic (water pill) or vitamin or mineral supplements that contain calcium or vitamin D.

Citrolex topical is for use only on areas of psoriasis. Avoid getting it on healthy skin areas. Citrolex topical should not be applied to the face or the vaginal area.

Stop using this medication and call your doctor if you have a serious side effect such as blistering or severe redness, itching, or other irritation of treated skin.

Using Citrolex topical can affect your body's ability to metabolize calcium. This can result in high levels of calcium in your blood (hypercalcemia). Symptoms of this condition include nausea, loss of appetite, constipation, increased thirst and urination, muscle weakness, confusion, and feeling tired or restless. Call your doctor if you have any of these symptoms.

Use Citrolex solution as directed by your doctor. Check the label on the medicine for exact dosing instructions.

• Citrolex solution is usually given as an injection at your doctor's office, hospital, or clinic. If you will be using Citrolex solution at home, a health care provider will teach you how to use it. Be sure you understand how to use Citrolex solution. Follow the procedures you are taught when you use a dose. Contact your health care provider if you have any questions.
• Do not use Citrolex solution if it contains particles, is cloudy or discolored, or if the vial is cracked or damaged.
• Keep this product, as well as syringes and needles, out of the reach of children and pets. Do not reuse needles, syringes, or other materials. Ask your health care provider how to dispose of these materials after use. Follow all local rules for disposal.
• If you miss a dose of Citrolex solution and you are using 1 dose every other day, use the missed dose if you remember the same day. If you do not remember the dose until the next day, use the missed dose, and then skip a day. Return to your every other day schedule.

Ask your health care provider any questions you may have about how to use Citrolex solution.

Citrolex is a man-made active form of vitamin D. Most people get enough vitamin D from exposure to the sun and from fortified food products (e.g., dairy products, vitamins). Vitamin D helps control parathyroid hormone and the levels of certain minerals (e.g., calcium, phosphorus) that are needed for building and keeping strong bones.

Before regular vitamin D can be used by the body, it needs to be changed to the active form by the liver and kidneys. Citrolex is used in patients with kidney disease who can't make enough of the active form of Vitamin D. This medication is also used to prevent and treat certain types of calcium/phosphorus/parathyroid problems that can happen with long-term kidney dialysis or hypoparathyroidism. Citrolex is usually used along with specific diet recommendations and sometimes other medications.

OTHER USES: This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

This drug may also be used to treat and prevent certain bone diseases (rickets, osteomalacia) when regular vitamin D does not work.

How to use Citrolex

Take this medication by mouth with or without food, usually once daily or as directed by your doctor. If you are using the liquid form, measure your dose with a special measuring spoon or device. Do not use a normal household spoon since you may not get the correct dose.

Dosage is based on your medical condition and response to therapy. Your doctor may start you on a low dose and adjust the dose slowly to find the best dose for you. Follow your doctor's directions carefully. Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time each day.

It is very important to follow the diet recommended by your doctor to get the most benefit from this medication and to prevent serious side effects. Do not take other supplements/vitamins (e.g., calcium, vitamin D) unless ordered by your doctor.

Certain medications (bile acid sequestrants such as cholestyramine/colestipol, mineral oil, orlistat) can decrease the absorption of vitamin D. Therefore, separate your doses of these medications as far as possible from your doses of Citrolex (at least 2 hours apart, longer if possible). It may be easiest to take Citrolex at bedtime if you are also taking these other medications. Ask your doctor or pharmacist about finding a good dosing schedule that will work with all your medications.

See also:
What other drugs will affect Citrolex?

Cholestyramine:

Cholestyramine has been reported to reduce intestinal absorption of fat-soluble vitamins; as such it may impair intestinal absorption of Citrolex.

Phenytoin/Phenobarbital:

The coadministration of phenytoin or phenobarbital will not affect plasma concentrations of Citrolex, but may reduce endogenous plasma levels of 25(OH)D3 by accelerating metabolism. Since blood level of Citrolex will be reduced, higher doses of Citrolex may be necessary if these drugs are administered simultaneously.

Thiazides:

Thiazides are known to induce hypercalcemia by the reduction of calcium excretion in urine. Some reports have shown that the concomitant administration of thiazides with Citrolex causes hypercalcemia. Therefore, precaution should be taken when coadministration is necessary.

Digitalis:

Citrolex dosage must be determined with care in patients undergoing treatment with digitalis, as hypercalcemia in such patients may precipitate cardiac arrhythmias.

Ketoconazole:

Ketoconazole may inhibit both synthetic and catabolic enzymes of Citrolex. Reductions in serum endogenous Citrolex concentrations have been observed following the administration of 300 mg/day to 1200 mg/day ketoconazole for a week to healthy men. However, in vivo drug interaction studies of ketoconazole with Citrolex have not been investigated.

Corticosteroids:

A relationship of functional antagonism exists between vitamin D analogues, which promote calcium absorption, and corticosteroids, which inhibit calcium absorption.

Phosphate-Binding Agents:

Since Citrolex also has an effect on phosphate transport in the intestine, kidneys and bones, the dosage of phosphate-binding agents must be adjusted in accordance with the serum phosphate concentration.

Vitamin D:

Since Citrolex is the most potent active metabolite of vitamin D3, pharmacological doses of vitamin D and its derivatives should be withheld during treatment with Citrolex to avoid possible additive effects and hypercalcemia.

Calcium Supplements:

Uncontrolled intake of additional calcium-containing preparations should be avoided.

Magnesium:

Magnesium-containing preparations (e.g., antacids) may cause hypermagnesemia and should therefore not be taken during therapy with Citrolex by patients on chronic renal dialysis.

See also:
What are the possible side effects of Citrolex?

Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rate observed in practice.

Clinical Studies Experience

Citrolex Ointment was studied in two vehicle-controlled studies (419 subjects), and in one open label study (324 subjects). The table below describes exposure to Citrolex Ointment in 743 subjects, including 239 exposed for 6 months and 116 exposed for one year.

Four hundred and nineteen subjects were treated with Citrolex Ointment twice daily for 8 weeks. The population included subjects ages 13 to 87, males (284) and females (135), Caucasians (372) and non-Caucasians (47); with mild (105) to moderate (313) chronic plaque psoriasis.

Among subjects having laboratory monitoring, hypercalcemia was observed in 24% (18/74) of subjects exposed to active drug and in 16% (13/79) of subjects exposed to vehicle, however the elevation were less than 10% above the upper limit of normal

The open label study enrolled 324 subjects with psoriasis who were then treated for up to 52 weeks. Adverse events reported at a rate of greater than or equal to 3% of subjects treated with Citrolex Ointment were lab test abnormality (8%), urine abnormality (4%), psoriasis (4%), hyperciuria (3%), and pruritus (3%). Kidney stones were reported in 3 subjects and confirmed in two.

Postmarketing Experience

The following adverse reactions have been identified during the world-wide post-approval use of Citrolex Ointment: acute blistering dermatitis, erythema, pruritus, skin burning sensation, and skin discomfort. Because these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.