Estabilidad

4,318 views

Published on

Published in: Health & Medicine, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
4,318
On SlideShare
0
From Embeds
0
Number of Embeds
18
Actions
Shares
0
Downloads
74
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Estabilidad

  1. 1. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Estabilidad de Medicamentos Contenido en sustancia activa Caracteristicas esenciales de calidad: Periodo de validez: − Contenido en sustancia activa − reducción del 10% en sustancia activa − Forma farmacéutica y caracteres − Toxicidad no aumenta debido a productos de organolépticos degradación − Flora microbiana Fecha de caducidad: mes y año − Toxicidad Periodo de validez máximo 5 años (RD − Biodisponibilidad 736/1987 de 17 de marzo) Estables, seguros, eficaces Depto. Farmacia y Depto. Farmacia y 1 2 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Estudios de estabilidad Alteraciones de los medicamentos Sobre la sustancia activa Inestabilidad Física Fase de preformulación: Inestabilidad Química − Sólido y disolución Inestabilidad Microbiológica − Compatibilidad con excipientes − Estabilidad frente a operaciones básicas Especialidad terminada − Ensayos a largo plazo − Ensayos de envejecimiento acelerado. Depto. Farmacia y Depto. Farmacia y 3 4 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 1
  2. 2. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Inestabilidad Física: alteración de las Inestabilidad química caracteristicas galénicas Consecuencias: Cinética química − Aspecto Orden y molecularidad de la reacción − Regularidad de la dosificación − Biodisponibilidad (caducidad biofarmacéutica) Vias degradación física: − Polimorfismo − Crecimiento cristalino − Sedimentación − Floculación − Coalescencia Depto. Farmacia y Depto. Farmacia y 5 6 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Stability Calculations Stability Calculations P D W a typical chemical reaction − Reaction rate ∝ [D]*[W] P D W D and W, quot;collidingquot; to form one or more product molecules, d[D] − α[D][W] the rate of reaction: proportional to the number of collisions a dt the number of collisions is proportional to the product of the concentrations of the two species: − we let k2 be the rate constant Reaction rate ∝ [D]*[W] − d[D] − = k 2 [D][W] Reaction rate corresponds to the rate of loss of D and is denoted (d[D]/dt) dt Depto. Farmacia y Depto. Farmacia y 7 8 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 2
  3. 3. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Stability Calculations Stability Calculations Order of reaction: Order of reaction: sum of the exponents of the concentration terms in the rate equation d[D] − = k 2 [D][W] dt − If the water concentration W is held constant (by having a d[D] − = k 2 [D][W] large excess, as in most solutions) then : dt d[D] − − k1[D] where k1= k2 [W] dt Second order reaction and the reaction is apparent first order or pseudo first order Depto. Farmacia y Depto. Farmacia y 9 10 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Stability Calculations Order of reaction: − If, now, in addition, we also fix the drug Orden Ecuación Unidades k concentration (e.g., by making a suspension), the velocidad equation becomes: C*t-1 0 -dC/dt=k d[D] − = k0 t-1 dt 1 -dC/dt=-k*C -dC/dt=k*C2 C-1*t-1 2 where k0 = k1[D] = k2[D][W] -dC/dt=k*C*B -dC/dt=k*Cn Cn-1*t-1 n and the reaction is apparent zero order Depto. Farmacia y Depto. Farmacia y 11 12 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 3
  4. 4. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. First-Order Calculations [D] = [D]0 e − k1t D P Orden Ecuación Ecuación velocidad integrada First order First order 0 -dC/dt=k C = C0 − k ⋅ t 1000.0 L n C o n c e n tra tio n 500.0 C o n c e n tra tio n 400.0 1 -dC/dt=-k*C 100.0 − k ⋅t 300.0 C = C0 ⋅ e 200.0 10.0 100.0 -dC/dt=k*C2 2 1 1 = + k ⋅t 1.0 0.0 C C0 0 100 200 300 400 500 0 100 200 300 400 500 Time (min) Time (min) T1/2 Depto. Farmacia y Depto. Farmacia y 13 14 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. First-Order Calculations First-Order Calculations The half-life, t½: The shelf-life, t90: usually taken to be the time for [D] to reach 0.90[D], that is, is the time for [D] to become [D]/2, 10% decomposition, [D]0 = ln[D]0 − k1t 12 ln 0.105 2 t 90 = 0.693 ln 2 k1 t 12 = = t 12 k1 k1 Depto. Farmacia y Depto. Farmacia y 15 16 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 4
  5. 5. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. First-Order Calculations Zero-Order Calculations rate equation with no concentration dependence. Example: aspirin (acetylsalicylic acid) d[D] − = k0 at pH 2.5 the (pseudo-first-order) rate constant is 5 dt x 10-7s-1 at 25ºC. Integrating from t = 0 to t = t with [D] = [D]0 at t = 0, half-life [ D] t ∫ d[D] = − ∫ k 0dt 0.693 t 12 = = 1.39 x 106 s 5 x 10-7 [ D]0 0 shelf life 0.105 t 90 = = 2.1 x 105 s [D] = [D]0 - k0*t 5 x 10-7 Depto. Farmacia y Depto. Farmacia y 17 18 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Zero-Order Calculations Zero-Order Calculations [D] = [D]0 - k0*t D] = [D]0 - k0*t Zero order Half life 1000 900 800 0.5[D]0 t 12 = 700 Concentration 600 k0 500 Shelf-life 400 300 200 100 0.1[D]0 0 t 90 = 0 20 40 60 80 Time mins k0 0.5[D]0 t 12 = k0 Depto. Farmacia y Depto. Farmacia y 19 20 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 5
  6. 6. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Zero-Order Calculations TEMPERATURE EFFECTS Example: aspirin (acetylsalicylic acid) at pH 2.5 the (pseudo-first-order) rate constant is Activation Energy Calculations 5 x 10-7s-1 at 25ºC. Reaction rates are proportional to the number of collisions per unit time. Aspirin solubility 0.33 g/100 mL. for an aspirin suspension: zero-order rate the number of collisions increases as the temperature increases. k0 = 5 x 10-7s-1 x 0.33 g/100 mL = The reaction rate constant is observed to have an exponential dependence on temperature described by the Arrhenius equation k0 = 1.65 x 10-7 g/(100mL * s) k = A exp(-Ea/RT) Dose of aspirin: 650 mg/teaspoon(5 mL) = 13 g/100 mL. − k :reaction rate constant − A :constant shelf life − Ea: activation energy of the chemical reaction − T : the absolute temperature (t ºC + 273.16ºC). (0.1)(13) t 90 = = 7.9 x 106 s=91 days log k = log A - Ea/2.303RT -7 1.65 x 10 Depto. Farmacia y Depto. Farmacia y 21 22 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. TEMPERATURE EFFECTS TEMPERATURE EFFECTS Typical Arrhenius plot of log k against 1/T, 60 4.5 50 4 3.5 Energy Kcal/mol Eact= 12 Kcal/mol 3 Log K 40 2.5 2 30 1.5 A+B 1 reactants 0.5 20 0 3 3.2 3.4 3.6 3.8 B+C 10 (1/T(Kº))*1000 products Slope= 3.51*103 0 Ea= 3.51*103*(2.303)*(1.987)=16.1 Kcal/mol Extent of reaction Depto. Farmacia y Depto. Farmacia y 23 24 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 6
  7. 7. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. TEMPERATURE EFFECTS TEMPERATURE EFFECTS Example: Compound Reaction Ea (kcal/mol) Sulfacetamide. Ascorbic Acid Oxidation 23 first-order rate constant in the pH-independent region (5-11) Aspirin Hydrolysis 14 K= 9 x 10-6 s-1 at 120ºC. Atropine Hydrolysis 14 Ea= 22.9 kcal/mol at pH 7.4. Calculate the shelf life at 25ºC. Benzocaine Hydrolysis 19 Chloramphenicol Hydrolysis 20 −22900 ⎛ 1 1⎞ − Ea ⎛ 1 1 ⎞ k 25 k2 Epinephrine Oxidation 23 = − = ⎜−⎟ ⎜ ⎟ log log k120 (2.3)(1.987) ⎝ 298 393 ⎠ k1 2.303R ⎝ T2 T1 ⎠ Procaine Hydrolysis 14 Thiamine Hydrolysis 20 k 25 = 8.7 x 10-5 k25 = (8.7 x 10-5) (9 x 10-6 s-1) = 7.85 x 10-10 s-1 k120 Activation Energies for Some Drug Decomposition Reactions 0.105 t 90 = = 1.34 x 108 s 4.25 years 7.85 x 10-10 s-1 Depto. Farmacia y Depto. Farmacia y 25 26 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. TEMPERATURE EFFECTS TEMPERATURE EFFECTS Example Answer: (a) from the Arrhenius plot of the data we obtain The following rate constants were determined for 5-fluorouracil The slope decomposition at pH 9.90. B= -12.31=Ea/R Ea = 24.5 kcal/mol 106 k (s -1 ) t (ºC) 80 0.96 10 70 0.32 60 0.118 1 Log k 0.1 Determine the activation energy at this pH; (a) Extrapolate the graph to room temperature (25ºC) and (b) determine the rate constant and shelf life at this temperature. 0.01 2.800 2.850 2.900 2.950 3.000 3.050 1/T (Kº) Depto. Farmacia y Depto. Farmacia y 27 28 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 7
  8. 8. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. TEMPERATURE EFFECTS Q10-Value Calculations: (b) From extrapolation of the graph to 25ºC (1/T = 0.00335), Consider the ratio of rate constants kT2/kTl at two temperatures we obtain log k25ºC = -8.86. k25ºC = 1.38 x 10-9 s-1 T1 and T2. Consider T1=T2+10º t90 = 7.6 x 107 s = 2.4 years The quantity Q10 is defined as 10 k (T +10) Q10 = 1 kT Log k The Q10 factor can be calculated from the next equation: 0.1 ⎡E 1 ⎞⎤ ⎛1 k (T +10) Q10 = = exp ⎢ − a −⎟ 0.01 ⎜ T + 10 T ⎠ ⎥ 2.800 2.850 2.900 2.950 3.000 3.050 ⎝ ⎣R ⎦ kT 1/T (Kº) Note that Ea is always positive. Depto. Farmacia y Depto. Farmacia y 29 30 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Q10-Value Calculations: Q10-Value Calculations: For an arbitrary change in temperature, ΔT = T2 - T1, The activation energies for drug decompositions usually fall in the range 12 to 24 kcal/mol. Next table gives values of Ea corresponding to three rounded values of Q10. These values of Q10 = 2, 3, or 4 to represent low, average, and high estimates of Q10 when Ea is unknown k (T +ΔT) = Q10( ΔT /10) Q ΔT = kT Q10 (30 to 20ºC) Ea (kcal/mol) 2.0 12.2 3.0 19.4 4.0 24.5 Depto. Farmacia y Depto. Farmacia y 31 32 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 8
  9. 9. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Q10-Value Calculations: Q10-Value Calculations: For an arbitrary change in temperature, ΔT = T2 - T1, ⎡E ΔT (T + 10) ⎤ 10 Q ΔT = exp ⎢ a R (T + 10)(T) 10 (T + ΔT) ⎥ ⎣ ⎦ ⎡E ⎛ ⎞⎤ ΔT Q ΔT = exp ⎢ a ⎜ ⎟⎥ [ ΔT /10][(T +10) /(T +ΔT )] ⎣ R ⎝ (T + ΔT)(T) ⎠ ⎦ ⎡E ⎤ 10 = exp ⎢ a ⎥ ⎣ R (T + 10)(T)1 ⎦ Multiplying the exponential term by Q ΔT = Q10[ ΔT /10][(T +10) /(T +ΔT )] 10 T + 10 i 10 T + 10 This equation is exact. However, since T ≈ 300K, (T + 10)/(T + ∆T) ≈ 1, gives ⎡E 10 (T + 10) ⎤ ΔT k (T +ΔT) Q ΔT = exp ⎢ a Q10 ΔT /10 ⎥ Q ΔT = ⎣ R (R + ΔT)(T) 10 (T + 10) ⎦ kT Depto. Farmacia y Depto. Farmacia y 33 34 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Q10-Value Calculations: Q10-Value Calculations: Example Calculate the factors by which rate constants may (b) a 25 to 0ºC temperature change. Answer: change for: (a) a 25 to 50ºC temperature change (b) a 25 to 0ºC temperature change. ΔT = -25, Answer: k (0−25) = Q10 ( −25/10) Q−25 = (a) ΔT = +25, k0 k (25+ 25) Q+25 = = Q10 (25/10) k 25 = 1/5.7, 1/15.6, 1/32 for Q10 = 2, 3, 4, respectively Thus the rate decreases to between 1/6 and 1/32 of the initial = 5.7, 15.6, 32 for Q10 = 2, 3, 4, respectively rate. Thus the rate increases between 6-fold and 32-fold, with a probable average increase of about 16-fold. Depto. Farmacia y Depto. Farmacia y 35 36 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 9
  10. 10. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. SHELF-LIFE ESTIMATION METHODS Q10-Value Calculations: The expiration date is given for room temperature. What is • Q = 4 provides the largest estimate for the increase in rate the expected extension of the shelf life in a with increasing temperature, refrigerator? • Q = 2 provides the smallest reasonable estimate for the decrease with decreasing temperature. Example: Using Q10 = 2, 3, 4, calculate the half-life change from 70ºC to 25ºC for methyl paraben at pH 4. We have ΔT = 25 - 70 = -45, Q-45= 1/23, (Q10=2) Q-45= 1/140, (Q10=3) Q-45= 1/512, (Q10=4) Since k70ºC = 1.6 x 10-6 s-1 (from the monograph) then t½ (70ºC) = 4.3 x 107 s = 501 days t½ (25ºC) = 31 yr (Q =2) = 199 yr (Q = 3) The expiration date is given for refrigeration conditions. = 709 yr (Q = 4) How long may the product be left at room temperature? . Depto. Farmacia y Depto. Farmacia y 37 38 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. SHELF-LIFE ESTIMATION METHODS The expiration date is for room-temperature conditions, and it SHELF-LIFE ESTIMATION METHODS is desired to heat the product in sterilization. What percent decomposition can be expected at the higher temperature? The expiration date is for room-temperature conditions, and it is desired to heat the product in sterilization. What percent decomposition can be expected at the higher temperature? 0.1[D 0 ] Zero order t 90 = k0 a t 90 (T) = k (T1 +ΔT) 0.105 First order t 90 = k1 Problems of this type require estimates of the effect of temperature on the shelf life. Assuming we do not have exact Ea values available, we use the Q10 values of 2, 3, and 4 to make such estimates. Depto. Farmacia y Depto. Farmacia y 39 40 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 10
  11. 11. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. SHELF-LIFE ESTIMATION METHODS SHELF-LIFE ESTIMATION METHODS Example A. a The expiration period for a reconstituted product is 18 h at room t 90 (T2 ) = temperature. k T1 iQ10 ( ΔT /10) Estimate the expiration period when the product is stored in the refrigerator. or, since t90(T1) = a/kT1: ΔT = -20ºC, 18 t 90 (T1 ) t 90 (5º ) = t 90 (T2 ) = Q10 ( −20 /10) t (T ) Q10 ( ΔT /10) t 90 (T2 ) = 90( ΔT 1 Q10 /10) t90 (5ºC) = 18 * 22 = 72 h (Q = 2) = 18 *32 = 162 h (Q = 3) the estimate of t90(T2) is independent of the order. = 18 * 42 = 288 h (Q = 4) a positive ΔT (T2 > T1) reduces the shelf life, a negative ΔT(T2 < T1) increases it. conservative estimate would be 72 h and a likely estimate 162 h. Depto. Farmacia y Depto. Farmacia y 41 42 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. SHELF-LIFE ESTIMATION METHODS SHELF-LIFE ESTIMATION METHODS Example B. If the product has been stored for a known length of time A newly reconstituted product is labeled to be stable for 24 h in a at another temperature: refrigerator. What is the estimated shelf life at room temperature? compute the time interval at the specified 1. t90 (5ºC) = 24 h temperature that would give the equivalent 24 t 90 (25º ) = t 90 (T1 ) t 90 (T2 ) = decomposition to that which occurred at the actual Q10 (20 /10) Q10 ( ΔT /10) storage temperature and subtract this value from or add it to the label date for 2. t90 (25ºC) = 24/4 = 6 h (Q = 2) a new expiration date. = 24/9 = 2.7 h (Q = 3) = 24/16 = 1.5 h (Q = 4) Thus a likely value is about 3 h, with a conservative estimate of 1.5 h and a possible value of 6 h. Depto. Farmacia y Depto. Farmacia y 43 44 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 11
  12. 12. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. SHELF-LIFE ESTIMATION METHODS SHELF-LIFE ESTIMATION METHODS Example Example. The expiration date for a product is one year from the current date when The ampicillin monograph in the Physicians' Desk Reference (1) states stored in a refrigerator. The product has been stored-for one month at that the reconstituted suspension is stable for 14 days in a room temperature. If the product is now returned to the refrigerator, refrigerator. If the product is left at room temperature for 12 h, what what is the new expiration date? is the reduction in the expiration period? Answer One month at room temperature would be equivalent to t 90 (T1 ) → t 90 (T2 ) ⋅ Q10 ( ΔT /10) t 90 (T2 ) = t 90 (T1 ) → t 90 (T2 ) ⋅ Q10 ( ΔT /10) Q10 ( ΔT /10) t 90 (T2 ) = Q10 ( ΔT /10) 0.5 * 22 = 2 days (Q = 2) 1 *22 = 4 months (Q = 2) 0.5 * 32 = 4.5 days (Q = 3) 1 *32 = 9 months (Q = 3) 0.5 * 42 = 8 days (Q = 4) 1 *42 = 16 months (Q = 4) that is, 4, 9, or 16 months at 5ºC. The expected reduction is thus 4.5 days. The most likely estimate is 9 months, hence if the product is returned to the refrigerator, only 3 months would be left. Depto. Farmacia y Depto. Farmacia y 45 46 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Influencia del pH Influencia del pH Example1 pH-Rate profile for hydrolysis of citric acid anhydride at 25°C Example:pH-Rate profile for the dehydration of streptovitacin A at 70°C Depto. Farmacia y Depto. Farmacia y 47 48 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 12
  13. 13. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. D. pH EFFECTS (2). Sigmoid Curves D. pH EFFECTS (3). Bell-Shaped Curves Example2: Hydrolysis of aspirin. Some pH-rate profiles show maxima, often with a quot;bell where k3 > kl and kquot; > k'. shapedquot; peak. The rate equation is rate = k1[RCOOH][H+] + k'[RCOOH] + kquot;[RCOO-] + k3[RCOO-][OH-] The pKa of aspirin is 3.6, so the plateau region of the curve (pH 4 to 8) is accounted for primarily by Hydrolysis of penicillin G catalyzed the kquot; term, that is, hydrolysis of by 3,6-bis (dimethylaminomethyl)- the anion. This reaction is catechol. responsible for the instability of aspirin in solution dosage forms Catalysis is produced by the monoanion of the catechol derivative, pH-Rate profile for aspirin hydrolysis at 25°C Depto. Farmacia y Depto. Farmacia y 49 50 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Vías de degraddación química Inhibición de la oxidación Hidrólisis Proteger de la luz Oxidación Evitar presencia oxígeno Racemización Uso agentes antioxidantes Descarboxilación Polimerización Descomposición enzimática Depto. Farmacia y Depto. Farmacia y 51 52 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 13
  14. 14. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Antioxidantes sistemas hidrófilos Antioxidantes sistemas lipófilos Combinaciones inorgánicas de azufre: Naturales: Tocoferoles sulfitos (olor y sabor desagradables) Sintéticos y semisintéticos: − Combinaciones orgánicas de azufre: (olor Ácido gálico y ésteres del ácido gálico − y sabor desagradables) Ésteres ácido ascórbico − Butilhidroxianisol(BHA) Ácido ascórbico: tópicas, parenterales, − orales Butilhidroxitolueno(BHT) Depto. Farmacia y Depto. Farmacia y 53 54 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Sinérgicos Sobredosificación Reforzadores de acción: ácido fosfórico, Antibióticos, vitaminas citríco, tartárico Exceso de contenido activo que es Inactivadores de catalizadores: EDTA necesario tener en cuenta para garantizar la estabilidad, es decir, la compensación de la pérdida de principio activo prevista durante el periodo de conservación. Depto. Farmacia y Depto. Farmacia y 55 56 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 14
  15. 15. Estabilidad Estabilidad Tecnologia Farmacéutica. Tecnologia Farmacéutica. Inestabilidad biológica Clasificación conservantes Conservadores: requisitos Fenoles Tolerancia fisiológica Alcoholes alifáticos y aromáticos Compatibilidad Compuestos orgánicos de mercurio Estabilidad química Compuestos de amonio cuaternario Olor y sabor Ácidos carboxílicos Espectro activo Otros. Depto. Farmacia y Depto. Farmacia y 57 58 Tecnología Farmacéutica Tecnología Farmacéutica © Marival Bermejo © Marival Bermejo 15

×