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Cou 1:Cac dac tinh ly hoa cua thuoc ah den vc thuoc qua màng sinh vat:
- Thuoc la cac ptu thg' co trong luong =<600 & k.thuoc thay doi tu rat nho den rat lon.(PM=7: Li+ ; PM=59050)
- 1 so thuoc co ban chat la acid yeu(vd:aspirin) nhung 1 so thuoc lai la base yeu(vd: Pyrimethamin cation)
- De dc hap thu vao tb' thuan loi I' thuoc can fai co ty le tan (.) n' & tan (.) mo thich hop.
- Cac p.tu thuoc do dac trung boi hang so phan ly pKa:
Voi acid: pKa=pH + log ( [ptu]/[ion])
Voi base: pKa= pH + log([ion]/[ptu])
+1 acid huu co co pKa thap la 1 acid manh,1 base co pKa thap la 1 base yeu & ngc lai.
+ Nui coch #: khi 1 thuoc cu pH= pKa tho 50% thuoc o dang ion hoo (k khuech ton (.) màng; 50% k ion hoo (cu the khuech ton dc)--> gay td sinh hoc.
=> Nui chung 1 thuoc fan tan tot,de dc hap thu khi:
- cu trong lg p.tu thap.
- Ít bi ion hoo: fu thuoc pKa cua thuoc & pH cua mt.
- De tan (.) dich tiou hoo( tan (.) n').
- Tan dc (.) mo cua mang tb'.
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