Degradation in drugs maybe physical or chemical. Loss of water or absorption of water are physical degradation of drugs but hydrolysis is chemical degradation of drugs.
Drugs with ester or amide functional group react with one molecule of water and undergoes hydrolysis. Reaction between ionic drugs proceed faster than with neutral molecules. Further hydrolysis reactions are catalyzed by H+ and OH- ions. Hydroxyl ion catalyses hydrolysis 100 to 1000 times more actively than hydrogen ions. Drugs that contain ester group include Aspirin, procaine, atropine, etc while amide group containing drugs are chloramphenicol ampicillin, barbiturates, cephalosporins, etc.
PROTECTION AGAINST HYDROLYSIS : Hydrolysis reaction are known to occur in presence of moisture catalytic species H+ and OH- ions.
Buffers : Drugs maybe stabilized by the use of buffers. Type of buffer and optimum pH should be established. For example, pilocarpine is highly active in alkaline pH as it occurs as unionized form. But at alkaline pH it is highly irritating to the eye and also precipitates from the solution.
Therefore to prevent hydrolysis acidic pH has to be selected. Boric acid buffer of pH 5.0 with low buffer capacity is selected. A stronger buffer is not used since upon installation into the eye; pH of the solution is able to rise to that o tear secretion( pH 7.4) with consequently with the formation of the more active basic form of the drug.
Complexation : Hydrolysis of benzocaine in aqueous solution can be inhibited by the addition of caffeine. As a result of the complexation the attack of catalytic species on benzocaine can be reduced. The rate of hydrolysis will now depend on the amount of uncomplexed free benzocaine present in the solution. Other drugs that can be stabilized by complexation are prociane, tetracaine, etc.
Suppression Of Solubility : When solubility of drugs decreases the concentration of drug in the solution phase will be decreased. Hence the rate of hydrolysis is reduced.
Additives : Citrates, dextrose, sorbitol and gluconate, when combined with the drugs, the solubility of drugs will be suppressed probably because of decreased hydration o drug molecules.
Salts: The degradation of penicillin can be prevented by using poorly soluble procaine penicillin in dosage form.
Derivatives : Poorly water soluble derivatives such as esters of drugs can be used to reduce the tendency of hydrolysis. Example : erythromycin propionate, erythromycin stearate, chloramphenicol almitate.
Choice of solvent : Non-aqueous solvents such as alcohol and propylene glycol, have been used to replace portion, or all of water in a solution to reduce the hydrolysis of drugs. For example an elixir of phenobarbitone sodium contains considerable quantities of glycerol and alcohol.
Removal of water : Store the drug in dry form. When desired reconstitute the product. Example streptomycin dry powder for injection, ampicillin, amoxicillin dry powder for injection.
Degradation in drugs maybe physical or chemical. Loss of water or absorption of water are physical degradation of drugs but hydrolysis is chemical degradation of drugs.
Drugs with ester or amide functional group react with one molecule of water and undergoes hydrolysis. Reaction between ionic drugs proceed faster than with neutral molecules. Further hydrolysis reactions are catalyzed by H+ and OH- ions. Hydroxyl ion catalyses hydrolysis 100 to 1000 times more actively than hydrogen ions. Drugs that contain ester group include Aspirin, procaine, atropine, etc while amide group containing drugs are chloramphenicol ampicillin, barbiturates, cephalosporins, etc.
PROTECTION AGAINST HYDROLYSIS : Hydrolysis reaction are known to occur in presence of moisture catalytic species H+ and OH- ions.
Buffers : Drugs maybe stabilized by the use of buffers. Type of buffer and optimum pH should be established. For example, pilocarpine is highly active in alkaline pH as it occurs as unionized form. But at alkaline pH it is highly irritating to the eye and also precipitates from the solution.
Therefore to prevent hydrolysis acidic pH has to be selected. Boric acid buffer of pH 5.0 with low buffer capacity is selected. A stronger buffer is not used since upon installation into the eye; pH of the solution is able to rise to that o tear secretion( pH 7.4) with consequently with the formation of the more active basic form of the drug.
Complexation : Hydrolysis of benzocaine in aqueous solution can be inhibited by the addition of caffeine. As a result of the complexation the attack of catalytic species on benzocaine can be reduced. The rate of hydrolysis will now depend on the amount of uncomplexed free benzocaine present in the solution. Other drugs that can be stabilized by complexation are prociane, tetracaine, etc.
Suppression Of Solubility : When solubility of drugs decreases the concentration of drug in the solution phase will be decreased. Hence the rate of hydrolysis is reduced.
Additives : Citrates, dextrose, sorbitol and gluconate, when combined with the drugs, the solubility of drugs will be suppressed probably because of decreased hydration o drug molecules.
Salts: The degradation of penicillin can be prevented by using poorly soluble procaine penicillin in dosage form.
Derivatives : Poorly water soluble derivatives such as esters of drugs can be used to reduce the tendency of hydrolysis. Example : erythromycin propionate, erythromycin stearate, chloramphenicol almitate.
Choice of solvent : Non-aqueous solvents such as alcohol and propylene glycol, have been used to replace portion, or all of water in a solution to reduce the hydrolysis of drugs. For example an elixir of phenobarbitone sodium contains considerable quantities of glycerol and alcohol.
Removal of water : Store the drug in dry form. When desired reconstitute the product. Example streptomycin dry powder for injection, ampicillin, amoxicillin dry powder for injection.
As an amide it will be susceptible to strong acid or alkali, e.g. this study mentions alkaline hydrolysis: Removal of polyvinylpyrrolidone from wastewater using different methods - PubMed.
Other reagents: The hydrolysis of N-vinylpyrrolidone in the presence of polyacrylic acid and potassium persulphate.
As an amide it will be susceptible to strong acid or alkali, e.g. this study mentions alkaline hydrolysis: Removal of polyvinylpyrrolidone from wastewater using different methods - PubMed.
Other reagents: The hydrolysis of N-vinylpyrrolidone in the presence of polyacrylic acid and potassium persulphate.
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Degradation in drugs maybe physical or chemical. Loss of water or absorption of water are physical degradation of drugs but hydrolysis is chemical degradation of drugs.
Drugs with ester or amide functional group react with one molecule of water and undergoes hydrolysis. Reaction between ionic drugs proceed faster than with neutral molecules. Further hydrolysis reactions are catalyzed by H+ and OH- ions. Hydroxyl ion catalyses hydrolysis 100 to 1000 times more actively than hydrogen ions. Drugs that contain ester group include Aspirin, procaine, atropine, etc while amide group containing drugs are chloramphenicol ampicillin, barbiturates, cephalosporins, etc.
PROTECTION AGAINST HYDROLYSIS : Hydrolysis reaction are known to occur in presence of moisture catalytic species H+ and OH- ions.
Buffers : Drugs maybe stabilized by the use of buffers. Type of buffer and optimum pH should be established. For example, pilocarpine is highly active in alkaline pH as it occurs as unionized form. But at alkaline pH it is highly irritating to the eye and also precipitates from the solution.
Therefore to prevent hydrolysis acidic pH has to be selected. Boric acid buffer of pH 5.0 with low buffer capacity is selected. A stronger buffer is not used since upon installation into the eye; pH of the solution is able to rise to that o tear secretion( pH 7.4) with consequently with the formation of the more active basic form of the drug.
Complexation : Hydrolysis of benzocaine in aqueous solution can be inhibited by the addition of caffeine. As a result of the complexation the attack of catalytic species on benzocaine can be reduced. The rate of hydrolysis will now depend on the amount of uncomplexed free benzocaine present in the solution. Other drugs that can be stabilized by complexation are prociane, tetracaine, etc.
Suppression Of Solubility : When solubility of drugs decreases the concentration of drug in the solution phase will be decreased. Hence the rate of hydrolysis is reduced.
Additives : Citrates, dextrose, sorbitol and gluconate, when combined with the drugs, the solubility of drugs will be suppressed probably because of decreased hydration o drug molecules.
Salts: The degradation of penicillin can be prevented by using poorly soluble procaine penicillin in dosage form.
Derivatives : Poorly water soluble derivatives such as esters of drugs can be used to reduce the tendency of hydrolysis. Example : erythromycin propionate, erythromycin stearate, chloramphenicol almitate.
Choice of solvent : Non-aqueous solvents such as alcohol and propylene glycol, have been used to replace portion, or all of water in a solution to reduce the hydrolysis of drugs. For example an elixir of phenobarbitone sodium contains considerable quantities of glycerol and alcohol.
Removal of water : Store the drug in dry form. When desired reconstitute the product. Example streptomycin dry powder for injection, ampicillin, amoxicillin dry powder for injection.
HAPPY LEARNING!!
Thanks for A2A.
Degradation in drugs maybe physical or chemical. Loss of water or absorption of water are physical degradation of drugs but hydrolysis is chemical degradation of drugs.
Drugs with ester or amide functional group react with one molecule of water and undergoes hydrolysis. Reaction between ionic drugs proceed faster than with neutral molecules. Further hydrolysis reactions are catalyzed by H+ and OH- ions. Hydroxyl ion catalyses hydrolysis 100 to 1000 times more actively than hydrogen ions. Drugs that contain ester group include Aspirin, procaine, atropine, etc while amide group containing drugs are chloramphenicol ampicillin, barbiturates, cephalosporins, etc.
PROTECTION AGAINST HYDROLYSIS : Hydrolysis reaction are known to occur in presence of moisture catalytic species H+ and OH- ions.
Buffers : Drugs maybe stabilized by the use of buffers. Type of buffer and optimum pH should be established. For example, pilocarpine is highly active in alkaline pH as it occurs as unionized form. But at alkaline pH it is highly irritating to the eye and also precipitates from the solution.
Therefore to prevent hydrolysis acidic pH has to be selected. Boric acid buffer of pH 5.0 with low buffer capacity is selected. A stronger buffer is not used since upon installation into the eye; pH of the solution is able to rise to that o tear secretion( pH 7.4) with consequently with the formation of the more active basic form of the drug.
Complexation : Hydrolysis of benzocaine in aqueous solution can be inhibited by the addition of caffeine. As a result of the complexation the attack of catalytic species on benzocaine can be reduced. The rate of hydrolysis will now depend on the amount of uncomplexed free benzocaine present in the solution. Other drugs that can be stabilized by complexation are prociane, tetracaine, etc.
Suppression Of Solubility : When solubility of drugs decreases the concentration of drug in the solution phase will be decreased. Hence the rate of hydrolysis is reduced.
Additives : Citrates, dextrose, sorbitol and gluconate, when combined with the drugs, the solubility of drugs will be suppressed probably because of decreased hydration o drug molecules.
Salts: The degradation of penicillin can be prevented by using poorly soluble procaine penicillin in dosage form.
Derivatives : Poorly water soluble derivatives such as esters of drugs can be used to reduce the tendency of hydrolysis. Example : erythromycin propionate, erythromycin stearate, chloramphenicol almitate.
Choice of solvent : Non-aqueous solvents such as alcohol and propylene glycol, have been used to replace portion, or all of water in a solution to reduce the hydrolysis of drugs. For example an elixir of phenobarbitone sodium contains considerable quantities of glycerol and alcohol.
Removal of water : Store the drug in dry form. When desired reconstitute the product. Example streptomycin dry powder for injection, ampicillin, amoxicillin dry powder for injection.
HAPPY LEARNING!!
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