dihydrotachysterol; DHT, (Hytakerol, Dichystrolum, Antitanil)

Introduction

Tradename: Hytakerol

Indications

• acute or chronic post-operative tetany (especially thyroid surgery)
• idiopathic tetany
• hypoparathyroidism
• hypophosphatemia
• hypocalcemia
• renal osteodystrophy
• rickets

Dosage

• 0.8-2.4 mg QD for several days
• maintenance dose is 0.2-1.0 mg QD

Tabs: 0.125, 0.2, 0.4 mg.

Pharmacokinetics

• readily absorbed from intestine
• absorption may be reduced by hepatobiliary disease or steatorrhea
• maximal hypercalcemic effects occur in about 4 weeks after daily administration of a fixed dose
• 1/2life is 3-6 hours

elimination via liver

1/2life = 3-6 hours

Adverse effects

• common (> 10%)
  • hypercalcemia, hypercalciuria, elevated serum creatinine
• uncommon (< 1%)
  • nausea/vomiting, anorexia, convulsions, weakness, anemia, metastatic calcification, renal injury
• other
  • headache
  • somnolence
  • dry mouth
  • constipation
  • late adverse effects (uncommon (< 1%))
    • polyuria
    • polydipsia
    • irritability
    • weight loss

Drug interactions

• concurrent use of antacids may lead to hypermagnesemia in patients with renal failure
• cholestyramine, colestipol & mineral oil decrease serum vitamin D levels
• phenytoin & phenobarbital decrease serum vitamin D levels

• drug interaction(s) of statins with vitamin D

Mechanism of action

• vitamin D hydroxylated by hepatic microsomal enzymes to form cacifediol (25-OH vit D)
• calcifediol is hydroxylated in the kidneys to calcitriol (1,25 dihydroxy-vit D)
• calcitriol is the most active form of vitamin D, simulating intestinal transport of calcium & phosphorous

More general terms

• vitamin D

Database

• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3070
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=5281010
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=5311071