Slo-Cal technology. Slowly and continuously release calcium for efficient absorption. No. 1 doctor and pharmacist (Pharmacy Times Survey 2015) recommended calcium brand. Defy bone aging with Citracal calcium and a high level of vitamin D3. Adequate calcium and vitamin D throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis. With Slo-Cal technology, you can address your daily calcium needs with a single serving of Citracal. What is Citracal slow release 1200? Slo-Cal technology is a patent-pending technology that has been specifically developed to provide efficient calcium absorption in one daily dose. Citracal Slow Release 1200 contains 1200 mg of calcium plus 1000 IU of vitamin D3 in one daily dose.