Calcichew D3 Preference Study in Participants Eligible for Calcium and Vitamin D Supplementation.

The purpose of this study is to compare the preference of Calcichew D3 500/400 (containing 500 mg calcium and 400 IU of vitamin D) with Adcal-D3 600/400 (containing 600 mg of calcium and 400 IU of vitamin D) in Test Group 1, and to compare Calcichew D3 500/800 (containing 500 mg calcium and 800 IU vitamin D) with Kalcipos-D 500/800 (containing 500 mg of calcium and 800 IU of vitamin D) in Test Group 2.

The drug being tested in this study is called Calcichew D3 new formulations: Calcichew D3 500/400 and Calcichew D3 500/800. Calcichew D3 500/400 and Calcichew D3 500/800 are being tested to treat or prevent calcium or vitamin D deficiencies. Calcichew D3 500/400 will be compared to Adcal-D3 600/400 as prescribed in clinical practice and Calcichew D3 500/800 will be compared to Kalcipos-D 500/800 as prescribed in clinical practice.

This Crossover study will enroll approximately 276 patients equally divided between the two test groups (138 patients each). Within each test group, participants will be randomly assigned (by chance, like flipping a coin) to one of two treatment sequences, as described below.

Test Group 1:

* Calcichew D3 500/400 (containing 500 mg calcium and 400 IU of vitamin D) chewable tablet
* Adcal-D3 600/400 (containing 600 mg of calcium and 400 IU of vitamin D) chewable tablet

Test Group 2:

* Calcichew D3 500/800 (containing 500 mg calcium and 800 IU vitamin D) chewable tablets
* Kalcipos-D 500/800 (containing 500 mg of calcium and 800 IU of vitamin D) chewable tablets

Participants in Test Group 1 will take either Calcichew D3 500/400 or Adcal-D3 600/400 for 14 days and then will crossover to take either Calcichew D3 500/400 or Adcal-D3 600/400 treatment for 14 days. Participants in Test Group 2 will take either Calcichew D3 500/800 or Kalcipos-D 600/400 for 14 days and then will crossover to take either Calcichew D3 500/800 or Kalcipos-D treatment for 14 days.

This multi-center trial will be conducted In the United Kingdom and Germany. The overall time to participate in this study is 28 days. Participants will make multiple visits to the clinic including a final visit assessment at Day 28.

Eligibility Criteria:
Inclusion Criteria:

1. In the opinion of the investigator, the participant is capable of understanding and complying with protocol requirements.
2. Signs and dates a written, informed consent form and any required privacy authorization prior to the initiation of any study procedures.
3. Is eligible for or currently receiving treatment with calcium and vitamin D supplement as determined by the treating clinician in accordance with local treatment guidelines.
4. Eligible participants will either be:

   1. Aged 65 years or older requiring calcium and vitamin D supplementation for the prevention or treatment of deficiencies, or
   2. Aged 18 years or older that require calcium and vitamin D as an adjunct to specific osteoporosis treatment in participants at risk of calcium and vitamin D deficiencies.
5. Is male or female.
6. A female participant of childbearing potential who is sexually active with a nonsterilized male partner agrees to use routinely adequate contraception from signing of informed consent throughout the duration of the study, and for 12 weeks after last dose of study medication.

Exclusion Criteria:

1. Has received Calcichew D3, Adcal-D3 (if the participant is in Test Group 1) or Kalcipos-D (if the participant is in Test Group 2) within the 6 months prior to the first dose of study medication.
2. Has received any investigational compound within 30 days prior to Screening.
3. Has a disease and/or condition resulting in hypercalcaemia and/or hypercalciuria and for which the study drugs are contraindicated e.g. Zollinger-Ellison syndrome, nephrolithiasis.
4. Has any of the contraindications listed in the corresponding Summary of Product Characteristics (SPC) of the study drug that the participant may receive depending on the Test Group: Calcichew D3 or Adcal-D3 (if the participant is in Test Group 1); Calcichew D3 or Kalcipos-D (if the participant is in Test Group 2).
5. Is an immediate family member, study site employee, or is in a dependant relationship with a study site employee who is involved in conduct of this study (eg, spouse, parent, child, sibling) or may consent under duress.
6. Has a history of hypersensitivity or allergies to the active substances or to any of the excipients in the investigational products.
7. Has a history of known fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency.
8. If female, the participant is pregnant or lactating or intending to become pregnant before, during, or within 12 weeks after participating in this study; or intending to donate ova during such time period.