ca++ metaboloism-bds

8/14/2019 Ca++ Metaboloism-BDS

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Calcium:Functions

Excitation

contraction-in musclesExcitation secretion -inglands

Release oftransmittersfrom nerve

ending.

Intracellular

messengers forhormones,autacoids &

transmitters.Impulsegeneration in

heart-automaticity, A-V conduction.

Coagulation ofblood.


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Ca++ stores, HomeostasisHealthyadult menand

women 1300 and1000 g ofcalcium9% is in boned teeth

Normalserumcalcium

concentration8.5 to 10.4

mg/dl

Ionized (50%),protein-bound(40%),and complexed

(10%).

The extracellularCa2+ concentrationtightly controlled byhormones.Entry at the intestineand\its exit at the

kidney;These samehormones regulate

withdrawal from thelar e

8.5 to 10.4mg/dl


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Hormonal control of plasma concentration


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RemodellingBone[Ca++] turn

over:

Constant andcontinuous

Osteoclastic activity

followed byosteoblastic-Remodelling

Remodelling deficits

accumulate over lifetome

Diet, Ex., hormones,drugs etc

Remodelling

Remodelling

ResorptionNew bone formationClosely coupledDirectionally opposite


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Excretion

Absorption

Facilitated diffusion-All intestine

Carrier-DuodenumInfluenced by D

Phytate, oxalate,phosphate, TC

chelate Ca++

Phenytoin &Glucocorticoids

Excretion

Ionized Ca++ isfiltered

Reabsorbed

Influenced by

HormonesThiazide excretion

Ca++ requirement

300mg/d is lost

Same amount hasto be

supplememted


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Preparations and usesOral

Calcium chloride,lactate, carbonateetc.

Parenteral

Ca gluconate-i.v.Produces warmth oninjection

Uses

Ca gluconate slowi.v. followed byinfusion

Dietary

supplement ingrowing children,pregnancy andlactating mothers.

As adjuants inosteoporosis

Antacids


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hormone[PTH][Parathormone]

Actions:

Increases plasmaCa++Boneresorption.[Followedby new boneformation]

Kidney:Increases

reabsorptionIntestine: Indirectlyby increasing theformation of Calcitrol

Uses

Not used inhypoparathyroidism-Expensive,Parenteral route of

delivery, Vit D canproducecomparable resuts.

Teriparatide-

RecombinantSometimes used inosteoporosis

Diagnostic; Pseudo

and true


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CalcitoninCalcitonin

Calcitonin is aHYPOCALCEMIChormone actions-oppose those of PTH.

Secreted by thyroidparafollicular C cells

Preperations

Porcine

Synthetic

Route

S.C, i.m., Nasal spray.

Uses

Calcitonin useful inmanaginghypercalcemia[Malignancy]

Pagets disease toreduce bone pain

Osteoporosis

Not routinely used


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Alfacalcidol[1 OHD 3

Prohormone

Converted inbodyto active

hormone[Calcitriol]

Vit D


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Cutaneous

[Under

UV]

Dietary[Animal D3-

Dairy, Fish,egg yolk][Plant-D2]

Liver[25Hydroxylation]

25-OHVitD

Kidney[1

Hydroxylation]Kidney[1 -25(OH)2VitD]

Calcitriol Vitamin D synthesi

and activation


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Vit: D: Actions

[1]

synthesis of Ca++ binding proteins

[2]

[2] bone resorption

[3]

] Increases tubular reabsorption

Result= Plasmaconcentration

Of Ca++


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Vit D: Actions

synthesis of Ca++ binding proteins

bone resorption

Increases tubular reabsorption

Other actions

On Immunological cells On Lymphikine production

Neuronal, skeletal muscle function

Plasma

concn.Of Ca++


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Vit D DefeciencyNutrional

def.

Ca++Plasmaconcn

PTHsecretion

Ca++MobilizedFrom bones

Bonemineralization

Rickets[Children

]

Osteomalacia

[Adults]

Hypervitaminosis??PK??


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Preparations Uses

1g of

cholecalciferol=40i.uCalciferol

Cholecalciferol

Calcitriol

Alfacalidol-

Does not requirerenal hydroxylation

Can be used in renalimpairment

Calcipotriol[Analogue]

psoriasis

Prophylaxis-Dose??

D Resistant rickets[Hereditary]

DDependent[hereditary]

Calcitriol/alfacalcidol

Renal rickets

Calcitriol/alfacalcidol

Osteoporosis

Hypoparathyroidis

m


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OsteoporosisCharacterized by decreased bone strength

Common among postmenopausal women

Defective organic matrix

Pathological factors

Multifactorial-Etiology

ManagementLifestyle

HRT, SERM,BISPHOSPHONATES, Ca++, VitD


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BisphosphonatesCLASSIFICATIONI Generation 1-

10

EtidronateII Generation 100-

1000

Palmidrnate,Alendronate

III generation 1000-5000

Risedronate,Zoledronate

ACTIONS

Prevent osteoporosisPrevent bone

USES

Ostoporosis

Pagets disease

Hypercalcemia ofmalignancy

Bone pain inmetastasis

ADEGastric irritantsSevere esophagitisTo be swaalowed

with a glass of

water in sitting

ca++ metaboloism-bds

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