NAME: DUBE TRACY
REG NUMBER: R163092B
LEVEL: 2.2
MODULE: CT205 MEDICINAL CHEMISTRY
LECTURER: MS E SEBATA
ASSIGNMENT NUMBER: 2
, Drug metabolism refers to the biochemical changes that drugs undergo in the body, leading
to the formation of different metabolites with different effects .Rarely is only one metabolite
produced from a single drug. In general, most drugs are metabolized into molecules that are
more water soluble. Usually, drug metabolites are less active pharmacologically than the
parent compound. Drug metabolism occurs via two mechanisms Phase 1 and Phase 2
metabolism:
Phase 1 metabolism: This form of mechanism involves oxidation with the CYP450
enzymatic family.
Phase 2 metabolism: This involves attaching an endogenous substrate to the drug or to
Phase 1 metabolite. The enzymes responsible for these conjugative or add on
reactions are aptly named conjugative enzymes
PHASE 1 METABOLISM
Phase I biotransformation reactions introduce or expose functional groups on the drug with
the goal of increasing the polarity of the compound. Phase I reactions function to convert
lipophilic molecules into more polar molecules by introducing or unmasking a polar
functional group, such as -OH, -NH₂ Phase I reactions are catabolic .Phase I metabolism may
increase, decrease, or leave unaltered the drug's pharmacologic activity .Common reactions
that occur during metabolism are oxidation, reduction, hydrolysis. In phase I, a variety of
enzymes act to introduce reactive and polar groups into their substrates. One of the most
common modifications is hydroxylation catalysed by the cytochrome P-450-dependent
mixed-function oxidase system. These enzyme complexes act to incorporate an atom of
oxygen into non activated hydrocarbons, which can result in either the introduction of
hydroxyl groups or N-, O- and S-dealkylation of substrates. The reaction mechanism of the P-
450 oxidases proceeds through the reduction of cytochrome-bound oxygen and the generation
of a highly-reactive oxyferryl species it obeys the following order of reaction
O2 + NADPH + H+ + RH → NADP+ + H2O + ROH
Phase I reactions may occur by oxidation, reduction, hydrolysis, cyclization, decyclization,
and addition of oxygen or removal of hydrogen, carried out by mixed function oxidases, often
in the liver. These oxidative reactions typically involve a cytochrome P450 monooxygenase
(often abbreviated CYP), NADPH and oxygen. The classes of pharmaceutical drugs that
utilize this method for their metabolism include phenothiazines, paracetamol, and steroids. If
REG NUMBER: R163092B
LEVEL: 2.2
MODULE: CT205 MEDICINAL CHEMISTRY
LECTURER: MS E SEBATA
ASSIGNMENT NUMBER: 2
, Drug metabolism refers to the biochemical changes that drugs undergo in the body, leading
to the formation of different metabolites with different effects .Rarely is only one metabolite
produced from a single drug. In general, most drugs are metabolized into molecules that are
more water soluble. Usually, drug metabolites are less active pharmacologically than the
parent compound. Drug metabolism occurs via two mechanisms Phase 1 and Phase 2
metabolism:
Phase 1 metabolism: This form of mechanism involves oxidation with the CYP450
enzymatic family.
Phase 2 metabolism: This involves attaching an endogenous substrate to the drug or to
Phase 1 metabolite. The enzymes responsible for these conjugative or add on
reactions are aptly named conjugative enzymes
PHASE 1 METABOLISM
Phase I biotransformation reactions introduce or expose functional groups on the drug with
the goal of increasing the polarity of the compound. Phase I reactions function to convert
lipophilic molecules into more polar molecules by introducing or unmasking a polar
functional group, such as -OH, -NH₂ Phase I reactions are catabolic .Phase I metabolism may
increase, decrease, or leave unaltered the drug's pharmacologic activity .Common reactions
that occur during metabolism are oxidation, reduction, hydrolysis. In phase I, a variety of
enzymes act to introduce reactive and polar groups into their substrates. One of the most
common modifications is hydroxylation catalysed by the cytochrome P-450-dependent
mixed-function oxidase system. These enzyme complexes act to incorporate an atom of
oxygen into non activated hydrocarbons, which can result in either the introduction of
hydroxyl groups or N-, O- and S-dealkylation of substrates. The reaction mechanism of the P-
450 oxidases proceeds through the reduction of cytochrome-bound oxygen and the generation
of a highly-reactive oxyferryl species it obeys the following order of reaction
O2 + NADPH + H+ + RH → NADP+ + H2O + ROH
Phase I reactions may occur by oxidation, reduction, hydrolysis, cyclization, decyclization,
and addition of oxygen or removal of hydrogen, carried out by mixed function oxidases, often
in the liver. These oxidative reactions typically involve a cytochrome P450 monooxygenase
(often abbreviated CYP), NADPH and oxygen. The classes of pharmaceutical drugs that
utilize this method for their metabolism include phenothiazines, paracetamol, and steroids. If
