B Gio Dc v o To Trng i hc Nng Lm TP. H Ch Minh

BI GING DC L TH Y

B MN NI KHOA DC L

Ging vin bin son : TS. NGUYN NH PHO

ThS. V TH TR AN

2003

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NI DUNG

Trang

CHNG 1. M U 3 V Th Tr An

CHNG 2. THUC TC NG LN H THN KINH 9 Nguyn Nh Pho

CHNG 3. THUC KHNG KHUN 20 V Th Tr An

CHNG 4. THUC ST TRNG, KH TRNG 38 V Th Tr An

CHNG 5. THUC TR K SINH TRNG 42 V Th Tr An

CHNG 6. THUC KHNG VIM V KHNG HISTAMIN 50 V Th Tr An

CHNG 7. THUC TC NG LN H MU 54 V Th Tr An

CHNG 8. THUC TC NG LN H H HP, TIU HA 60 V Th Tr An

CHNG 9. THUC TC NG LN H SINH DC TIT NIU 64 V Th Tr An

TI LIU THAM KHO 67

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CHNG 1: I CNG I. Gii thiu mn hc: Cc khi nim - Dc l hc (Pharmacology) l mn hc nghin cu v nguyn l v nhng qui lut tc dng ln nhau gia thuc v c th sinh vt trong chia thnh hai phn: - Dc ng hc (Pharmacokinetics) nghin cu v tc ng ca c th i vi thuc hay nghin cu v s phn ca thuc trong c th qua cc qu trnh hp thu, phn b chuyn ha v o thi. - Dc lc hc (Pharmacodynamics) nghin cu v tc ng ca thuc i vi c th v mt tnh cht cng v thi gian. - Thuc l nhng cht (c ngun gc t nhin, tng hp hay bn tng hp) khi c a vo c th sinh vt s c tc ng lm thay i chc nng ca c th. S thay i ny c th l hu ch nh trong iu tr hoc c th gy tc hi nh trong trng hp ng c. Do ranh gii gia thc n, thuc v cht c thng khng r rt, ph thuc nhiu yu t trong liu lng l quan trng II. Dc ng hc 2.1. S hp thu: l qu trnh dc phm thm nhp vo ni mi trng 2.1.1. Cc phng cch vn chuyn 2.1.1.1.Vn chuyn th ng (khuych tn) - Ch ph thuc tnh cht ha l ca mng v thuc - Thun chiu gradien nng - Khng tn nng lng C 3 cch: * Qua lp lipid ca mng: thung cc cht tan trong li pid, khng ion ha (khng phn cc) d qua hn * Qua l ca mng: ty thuc ng knh ca l v trng lng phn t ca thuc. ng knh ny cng thay i ty tng m. V d: d mao mch =40 A0 d ni khc = 4 A0 * Qua khe cc t bo: khong cch gia cc khe cng thay i ty m V d: mch mu > rut > m thn kinh 2.1.1.2. Vn chuyn ch ng (tch cc) - Cn c cht chuyn ch (cht mang) - Vn chuyn ngc chiu gradien nng - Cn cung cp nng lng 2.1.2. Cc ng cp thuc thng dng trong th y 2.1.2.1. ng ung (ng tiu ha, oral, per os, P.O) Thuc c hp thu qua nim mc d dy, rut non u im ca ng cp thuc ny l tin li, d thc hin v an ton nht. Nhc im l s hp thu ph thuc nhiu yu t nh tnh trng ca d dy rut, thnh phn

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thc n. ng cp ny thuc c th b mt tc dng do pH thp ca dch v v cc enzym tiu ha c th ph hy thuc. i vi gia sc, vic cung cp thuc bng ng ung cn phi ch v liu lng v c th s khng cung cp c bit l trng hp trn vo thc n, nc ung. Thm vo , ng cp ny khng nn s dng i vi cc thuc c mi v kh chu, gy kch ng, cc thuc c tnh ion ha. 2.1.2.2. ng tim chch (ng ngoi tiu ha, parenteral) Thuc khuch tn th ng do chnh lch nng , d mao mch ln nn nhiu phn t thuc qua c. u im ca ng cp ny l thuc c hp thu nhanh v nhanh c tc ng. Cp thuc bng ng tim chch s gii quyt c nhng hn ch ca ng ung. Hn ch ca ng tim chch l i hi iu kin v trng, ngi cp thuc phi c k thut. Thuc dng cho ng tim chch thng t tin, km an ton v gy au. * Tim di da (subcutaneous injection, S.C) Thuc s c tc dng sau 30-60 pht, liu dng thng ch bng 1/3 liu ung Nnb trnh dng ng ny cho ccthuc c tnh kch ng, gy xt. * Tim bp (intramuscular, I.M) Thuc c tc dng nhanh hn khong 10-30 pht, liu dng bng 1/2 liu ung C th tim cc thuc m ng tim di da gy au xt. * Tim tnh mch (intravenous, I.V)

y thuc khng phi c hp thu na m l thu nhp nhanh chng v ton vn vo h tun hon chung, c tc dng sau 30 giy n 5 pht, liu cp bng 1/2-1/4 liu ung. ng tim ny thng p dng cho cc trng hp cp cu hoc cn thuc c tc dng tc thi. Cn ht sc thn trng khi dng ng cp ny, lu s ng trng, tc cp thuc v tuyt i khng s dng cc dung mi l cc cht du, cht khng tan.

* Tim phc m (intraperitoneal, I.P) Vi b mt hp thu ln cng mng li mao mch pht trin ca phc m, thuc c

hp thu nhanh chng gn bng ng tim tnh mch. S dng ng cp ny cn ch trnh gy vim nhim, thng rut, bng quang. ng cp ny thng dng khi cn cp mt lng ln thuc trong thi gian ngn m ng tim tnh mch kh thc hin. * Tim trong da (intradermic I.D) thng gp trong cc th nghim lao t (tuberculin test) hoc th d ng vi khng sinh 2.1.2.3. Cc ng cp thuc khc: * ng thm qua mng nhy kh qun, cung phi, b m ph nang Thng p dng cho cc thuc bay hi hoc d bay hi, kh dung. Thuc s c hp thu qua din tch rng ln ca b my h hp v mng mao qun v h tun hon chung. * ng trc trng (rectum mucosa) Thuc s trnh c tc ng chuyn ha ti gan. C th dng cho cc thuc c mi v kh

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chu. Tuy nhin, ng cp ny ch p dng cho cc thuc khng b hy bi men penicillinase. * ng bi ngoi da, t vo m o, t cung... 2.2. Phn b

Thuc vo h tun hon chung s c phn b ch yu n ni tc ng, t sinh ra tc ng dc l. Mt phn b chuyn ha hay cn gi l bin i sinh hc, mt phn nh n ni d tr v mt phn khc b thi ra ngoi. D c phn b u, thuc cng c th nm dng t do hoc kt hp vi cc thnh phn khc ca m. Vic phn b thuc mu ph thuc vo s v tr gn v i lc ca thuc vi protein. m, s phn b ph thuc l ha tnh ca thuc, mc tun hon ti m v i lc ca thuc vi m. 2.3. Chuyn ha (bin i sinh hc)

Ch yu do h microsomes ca gan m nhn, ngoi ra, cn c ti phi, thn, lch... thng qua cc phn ng oxyha, kh, thy phn, tng hp c bit l phn ng lin hp vi acid glucuronic to thnh nhng phn t ester c cc cao, tan trong nc, kh thm qua mng t bo, khng cn hot tnh dc lc v d o thi ra ngoi. 2.4. Bi thi

Thuc c bi thi qua rut (theo phn), qua thn (theo nc tiu), qua phi (theo hi th), qua cc tuyn tit (m hi, nc bt), qua sa...Trong quan trng nht l thn.

S bi thi thuc qua thn ph thuc 3 c ch: - Lc qua cu thn, ph thuc lng thuc gn vo protein huyt thanh v tc lc ca cu thn. - Bi tit ch ng qua biu m ng thn. - S ti hp thu t lng ng thn vo mu theo s khuch tn th ng. Do pH nc tiu nh hng n ti hp thu. iu ny c ng dng trong vic gii c trn nguyn tc l tng cc dng ion ha ca thuc, lm thuc d tan trong nc t d thi ra ngoi.

V d: + Ng c cc cht kim yu (Amphetamin, quinidin...) dng NH4Cl acid ha nc tiu. + Ng c cc cht acid yu (Streptomycin...) dng NaHCO3 kim ha nc tiu. Tm li: - Cc cht tan trong nc c bi thi ch yu qua ng tiu - Cc cht khng tan trong nc c bi thi ch yu qua phn. - Cc cht kh, d bay hi c bi thi ch yu qua ng h hp. - Cc kim loi nng (As, Hg...) c bi thi ch yu qua da, m hi. III. Dc lc hc 3.1. Receptor (ni tip nhn, im ch)

L bt c thnh phn no ca t bo, kt hp vi thuc v khi u mt chui cc hin tng sinh ha dn n cc tc ng dc lc. V bn cht ha hc, receptor l cc i phn t sinh hc nh acid nucleic, lipid mng t bo nhng hu ht chng c bn cht protein.

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Lin kt gia receptor vi thuc l cc lin kt ion, hydro, k nc, vanderwal v lin kt cng ha tr. 3.2. Cc cch tc dng ca thuc - Tc dng ti ch: l tc dng xut hin ngay ni ta cung cp thuc V d: st trng da: dit vi khun ti ch - Tc dng phn x: tc dng dc l c c thng qua s dn truyn kch thch t ni cung cp thuc n c quan khc qua h thn kinh trung ng V d: ngi amoniac: kch thch tun hon, h hp - Tc dng chn lc: l tc dng ring, c hiu i vi 1 hoc 1 s c quan V d: digitalin (Coramin) c tc dng u tin trn tim - Tc dng trc tip v gin tip: tc dng gin tip l hu qu ca tc dng trc tip V d: Tc dng trc tip ca cafein l tng cng tun hon, tc dng gin tip l gy li tiu - Tc dng chnh v tc dng ph: tc dng chnh l mc ch cn t ca iu tr, tc dng ph l tc dng khng mong mun, c khi cn gy c cho c th. Do , cc nh iu ch dc phm lc no cng c gng hn ch hoc loi b hon ton tc dng ph ca thuc V d: tc dng chnh ca chloramphenicol l tiu dit vi khun gy bnh, tc dng ph l gy suy ty, thiu mu v to. 3.3. Tng tc gia hai dc phm (thuc) 3.3.1. Hip lc: Dc phm A gi l hip lc vi dc phm B khi A lm tng hot tnh ca B v 3 phng din: thu ngn tim thi, tng cng tc ng, tng thi gian tc ng. ngha trong iu tr: - Phi hp thuc lm tng hot tnh m khng lm tng c tnh. - Trnh hin tng khng thuc. 3.3.2. i khng Hai dc phm i khng nhau khi hot tnh ca mt trong hai dc phm lm gim hay tiu hy hot tnh dc phm kia. ngha trong iu tr: - Trnh phi hp hai dc phm i khng dn n lm gim hiu lc thuc. - Gii c trong trng hp ng c. IV. Nhng yu t nh hng n tc dng ca dc phm 4.1. Cc yu t bn trong c th - Tui tc gia sc non, h thng chuyn ha v bi thi thuc cha hon chnh, trong khi gia sc gi chc nng ca cc c quan trn b gim nn khi dng thuc cho cc i tng trn cn phi thn trng. - Trng lng: cn c vo trng lng hoc din tch b mt c th tnh liu lng thuc cn cp. -Phi tnh: mc nhy cm vi thuc ca th c v th ci c th khc nhau V d: con ci nhy cm vi thuc ng, strychnin hn con c - Cch dng thuc: lin quan n hin tng quen thuc, l thuc thuc, khng thuc - iu kin dinh dng: trong thc n, protein c bit lin quan n hin tng gn kt thuc cng nh cc enzym chuyn ha thuc - Tnh trng bnh l: c bit l cc bnh v gan thn

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4.2. Yu t ngoi c th (lin quan n thuc) - Cu trc ha hc: 1 thay i (d rt nh) v cu to ha hc ca dc phm cng nh hng n tc dng ca dc phm . iu ny m ra cc kh nng rng ln cho cc nh khoa hc ch to ra cc thuc mi. V d: PABA yu t sinh trng ca vi khun Sulfonamid: thuc chng vi khun - Tnh cht vt l: c lin quan n . ha tan trong nc v trong lipid thuc c hp thu vo trong c th . bc hi: i vi cc loi thuc m bay hi . Dng bo ch: bt, nc, dung dch treo... - Liu dng v nng . Liu ti thiu c tc dng (liu ngng): lng thuc cho vo c th bt u c tc dng . Liu iu tr (thng cao hn liu ngng): c s dng lm sng nhm mc ch khi phc chc nng bnh thng ca c th v gy ri lon bnh l . Liu gy c (cao hn liu iu tr): liu bt u c nhng bnh l c hi . Liu gy cht (LD50) gy cht 50% ng vt th nghim. - Nhp cung cp thuc: ph thuc vo thi gian bn hy (T1/2) ca thuc T1/2 l t