Causes of slow metabolism
Sources of improper metabolism include:
- strict diets with low calorie content;
- unbalanced diet;
- no breakfast;
- stress, lack of sleep;
- deficiency of vitamins and minerals;
- gastrointestinal diseases of acute or chronic course;
- insufficient fluid intake.
The problem of slowing down metabolic processes may be associated with physical inactivity - insufficient physical activity.
How to speed up your metabolism through nutrition and exercise?
Nutrition and exercise are the most important components of losing weight, because it is not the speed that depends on them, but the quality. To speed up your metabolism, you need to provide yourself with a rational, balanced and fractional diet, an optimal drinking regime of at least 2 liters of water per day, as well as physical activity. It is not necessary to train hard in the gym; for the first time, you can include 20-minute workouts at home, then gradually move on to strength exercises in the gym. The number of workouts per week is at least 3.
Video
In the video, we suggest you familiarize yourself in more detail with the means that improve metabolic processes for weight loss.
Types of drugs
There are several types of medications that help speed up your metabolism.
These include:
- fat burning;
- reducing appetite;
- medications that stimulate metabolic processes;
- diuretics and laxatives;
- multivitamin complexes.
The greatest effect from using tablets to improve metabolism can be achieved if you combine the use of such drugs with an increase in physical activity and adherence to the principles of a healthy diet or diet.
Tablets to improve metabolism are taken only on the recommendation of a therapist and after consulting a nutritionist.
The therapy program includes:
- increased physical activity;
- compliance with the drinking regime;
- good sleep;
- adequate rest.
Fat burners
The drugs accelerate metabolic processes due to the rapid processing of fatty acids (lipotronics), increasing body temperature (thermogenics). Medicines are made from natural and synthetic ingredients.
Appetite suppressant pills
Funds are divided into two subgroups:
- affecting the saturation center in the hypothalamus;
- swelling when ingested.
Both types of drugs take part in metabolism through the production of certain hormones or additional enzymes.
Metabolism stimulants
The subgroup of medicines includes dietary supplements and tablets, originally intended for the treatment of certain pathologies. They were specially developed to speed up metabolic processes.
Diuretics and laxatives
The drugs do not have a direct effect on metabolic processes; they are used to remove accumulated fluid in tissues and empty the intestines of feces. Prescribed for intoxication and slagging of the body, at the same time accelerating biochemical processes.
Vitamin and mineral complexes
The metabolic rate directly depends on the nutrients supplied with food. Multivitamin complexes compensate for the shortcomings of an unbalanced diet, improving metabolism.
Don't miss the most popular article in the section: Laser hair removal on the face and body - how it is done, effectiveness, before and after photos, contraindications.
What does this mean?
Many people are looking for drugs that speed up metabolism, mainly for weight loss. Everyone knows what a huge role metabolism plays in gaining excess weight. On the one hand, the approach is correct: you need pills not for the problem itself, but for the cause that provokes its appearance. However, this principle does not work here, and here's why.
Medicines are developed to treat diseases. There is not a single code in the International Classification of Diseases for accelerating slow metabolism. And this can be explained very simply: his speed is an individual indicator, and each person has his own. There are no clearly defined standards for what exactly it should be so that everything in the body works like a clock. And if there is no disease, there is no drug to treat it.
But this does not mean at all that there are no pills to speed up the metabolism in the body. They exist, but this pharmacological property is secondary, additional to the main one. Without it, they simply will not achieve their final goal. Let's look at examples.
Xenical is a drug with the active ingredient orlistat, prescribed by official medicine for the treatment of obesity. To achieve weight loss, it reduces the absorption of fats, that is, it slows down lipolysis. And this is just one chemical reaction out of the 50 that make up metabolism. But this property of the tablets entails a chain of consequences that ultimately speed up (albeit not much) the metabolism.
Glucophage is a drug based on metmorphine for the treatment of diabetes mellitus. It makes receptors more sensitive to insulin, thereby accelerating the utilization of glucose by cells. And the consequence of this is the normalization of lipid metabolism, which entails changes in other metabolic processes.
Tablets prescribed for obesity (Xenical) and diabetes (Glucophage)
This dual effect of drugs results in people taking these pills, counting primarily on accelerating metabolism. While their main purpose is the treatment of quite serious diseases: diabetes, obesity, liver pathologies, bulimia. And those who do not suffer from them use them. This is fraught with a variety of consequences:
- if you’re lucky, taking the pills will still help speed up your metabolism without health complications;
- there will be no result;
- side effects will begin to manifest themselves: from dizziness to serious eating disorders;
- the drugs will have the opposite effect: metabolism may be further disrupted and slowed down;
- Healthy organs, which are targeted by the pharmacological action of the drug, may be damaged - after all, it is intended to treat them.
Metabolism is a set of biochemical processes occurring in the body, in which more than 50 substances are involved: amino acids, lipids, proteins, carbohydrates, isoprenoids, coenzymes, nucleotides, glycans, steroids, fatty acids, etc. There are no universal tablets that could would normalize such a complex system. Each drug is developed to eliminate a problem in a particular area: this one accelerates the absorption of carbohydrates, this one accelerates the absorption of proteins, the third one accelerates the breakdown of lipids, etc.
Therefore, draw the appropriate conclusions:
- There are no pills created specifically to speed up metabolism.
- Almost all weight loss drugs have a similar effect on the body, but it is only secondary.
- To take any medication, you must obtain a doctor's permission.
- Preference should be given to dietary supplements rather than narrowly targeted medications.
If you want to really speed up your metabolism, drink more water, eat right and get enough physical activity. This is a worthy alternative to any tablets.
The best vitamin and mineral complexes that promote weight loss
To improve metabolism, you can use multivitamin preparations. A sufficient amount of vitamins and minerals normalizes the functioning of the internal secretion organs and improves metabolic processes. The tablets are taken strictly according to the manufacturer's instructions - violation of the requirements can cause hypervitaminosis.
"Vitrum"
A multivitamin preparation containing 17 minerals and 13 vitamins.
The product is recommended for use in cases of hypovitaminosis, unbalanced diet, intense physical and mental stress, and after illnesses.
Due to the active substances, metabolic processes are accelerated and the functioning of the immune system is regulated.
Price per package:
- in Moscow – 444.21-1841.05 rubles;
- in the regions - 450.84-1883.05 rubles.
"Centrum"
A multivitamin complex is necessary to compensate for the deficiency of nutrients. The drug regulates the exchange of phosphorus and calcium, fats, carbohydrates and proteins, strengthens bone tissue.
Average cost of Centrum:
- in Moscow – 450-1650 rubles;
- in the regions - 501-544 rubles.
"Megaslim"
A special drug for weight loss that helps speed up fat burning. The product suppresses appetite, removes toxic substances and waste from the body.
The unique composition of Megaslim helps to avoid sagging skin during weight loss, headaches, and feelings of fatigue.
Packaging cost:
- Moscow and the region - 280.74-357 rubles;
- regions – 280.74 rubles.
"Duovit"
The multivitamin complex fights iron deficiency anemia and calcium deficiency. Prevents premature aging, protects against stress, accelerates metabolic processes in the body.
Packaging cost:
- in Moscow – 156-1198 rubles;
- in the regions - 184-478 rubles.
"Selmevit"
Consists of 11 vitamins and 9 minerals, helps fight stress and deficiency of nutrients. The drug is prescribed in the postoperative period, after injuries, and during exacerbation of chronic diseases.
Average price:
- in Moscow – 187.78-358.89 rubles;
- in the regions - 187.33-362.44 rubles.
“He will direct you - vitamins for an active life”
The drug is designed for people leading an active lifestyle. The complex of substances included in its composition stimulates energy processes, improves tissue trophism, corrects metabolism, and increases overall tone.
Average cost:
- in Moscow – 390-500 rubles;
- in the regions - 391-508 rubles.
"Turboslim"
A line of 21 drugs helps to get rid of excess weight. The dietary supplement improves immunity, strengthens the nervous system, and normalizes the functioning of the gastrointestinal tract.
Average cost:
- in Moscow – 36-1477 rubles;
- in the regions - 51-1477 rubles.
"Doppelhertz Active"
The product is intended to compensate for the deficiency of minerals and vitamins. Its components normalize the vital activity of cells: accelerate the processes of regeneration and metabolism.
The line of drugs includes weight loss complexes, multivitamins, Omega-3.
Price:
- Moscow and the region - 226-446.32 rubles;
- regions – 237-467 rub.
"Turboslim express weight loss"
Designed for extreme weight loss: 3 kg in 72 hours. Cleansing the body occurs due to a diuretic and laxative effect.
Cost in pharmacies:
- Moscow – 593-635 rubles;
- regions – 585-626 rubles.
"Alphabet Diet"
It is recommended for use during a week-long fast, a strict diet with the exclusion of certain foods.
Dietary supplements are prescribed after serious illnesses, when drying out the body before sports competitions. The price per package in Moscow and the regions is 206.65 rubles.
"Solgar"
The product line is divided into herbal remedies, minerals, vitamins, dietary supplements. The composition does not include dyes, sugar, starch, preservatives and chemical additives. The drugs help speed up metabolic processes and normalize the functioning of internal systems and organs. Average prices in Moscow and the regions are 444-5410 rubles.
The essence of metabolism
The concept includes a complex of reactions that affect the normal development of the body. Metabolism affects the rate at which calories are converted - they can be converted into energy or fat. When these processes slow down, energy is released more slowly, which leads to the accumulation of fats in reserve. This does not happen with rapid metabolism.
Metabolic rates are affected by age category, genetic predisposition, nutrition, proportions of fat and muscle tissue in the body. There are situations when metabolism is disrupted.
The main symptoms that accompany such problems include the following:
- Excess or underweight;
- Edema;
- Dyspnea;
- General fatigue;
- Impaired health of skin, nails and hair.
Indications and contraindications for the use of drugs
Tablets to improve metabolism are not recommended for use without a prescription from a physician.
Admission requirements are shown in the table:
Indications | Contraindications |
Poor nutrition | Cardiovascular and cancer diseases |
Anemia, bulimia | Pregnancy, breastfeeding |
Diabetes | Patients under 16 and after 60 years |
Hormonal disorders and obesity | Hypertension, thyrotoxicosis |
Physical inactivity, insufficient sleep | Pathologies of the gastrointestinal tract, cerebral circulation, kidneys |
Compulsive overeating | Glaucoma, liver dysfunction |
Hypovitaminosis, dehydration | Insomnia, mental illness |
Before starting a course of therapy, the patient must attend a consultation with a nutritionist or therapist. The doctor will select the appropriate complex based on the results of the diagnostic examination.
Don't miss the most popular article in the section: Morning exercises for those over 40, 50. Gymnastics exercises for weight loss, video lessons.
Tips for use
When using tablets that improve metabolism, it is important to fulfill the following conditions to achieve results:
- increase protein intake;
- avoid overeating;
- reduce the intervals between meals, you should eat at least 5 times a day, taking into account the reduction in portion sizes;
- stop drinking alcohol;
- limit foods containing sugar and fast carbohydrates, easily digestible fats in the diet;
- increase physical activity.
The drugs are taken strictly in accordance with the recommendations of a nutritionist or instructions for use.
Important! If signs of allergy or adverse reactions appear, stop using the products.
Dangerous consequences of using drugs to speed up metabolism
Independent use of means to activate metabolic processes can provoke:
- chronic allergies;
- mental disorders;
- damage to the peripheral nervous system;
- loss of muscle mass;
- depression;
- kidney and heart dysfunction;
- formation of hemorrhoids.
Diet pills will not give the expected results without regular exercise and diet. Improper use of medications to improve metabolic processes can cause the development of serious diseases.
Article design: Svetlana Ovsyanikova
How to increase metabolism after 40 years?
After 40 years, a woman begins to worry about some problems, such as menopause and menopause, it is at this time that a change in hormonal levels occurs.
Women may observe a change in their figure and the appearance of excess weight and problem areas on the body. It is during this period that it is necessary for the female body to select individual methods for losing weight and improving metabolism.
Very often, not every woman can take such measures on her own, and there is a need to turn to specialists. To speed up metabolism, it is necessary to restore the body’s capabilities; for this, it is often necessary to take various additional medications.
Experts advise following the following rules:
- Calculate the required number of calories daily; for this, the required number of calories is calculated specifically for the height and age of women.
- Reduce your intake of fats and carbohydrates. Almost all food should contain protein, this helps reduce weight and remove all harmful compounds from the body. Of the fats, it is recommended to leave only olive oil, which benefits the entire body.
- Eating whole grain products for breakfast, this type of food intake starts the body’s work and saturates it with energy for the first half of the day.
- Do physical exercise at least 2 times a week; you don’t need to go to the gym for this. It will be enough to perform basic exercises at home.
- Perform daily cardio exercises. This could be a run for 15 minutes in the morning, or a walk in the fresh air before bed.
- Drink plenty of fluids. To do this, it is better to use ordinary purified water without gas. This method will not only improve your metabolism, but also improve the appearance of your skin.
- Avoid stressful situations. Constant stressful situations can negatively affect the general condition of the body, causing a large number of negative consequences.
- Use special vitamin supplements. There are various vitamins on sale that are intended for people over 40 years of age.
In addition to all the recommended rules, it is necessary to adhere to healthy sleep and periodically allow the body to relax.
httpv://www.youtube.com/watch?v=embed/bCqLT9F1GXs
Smoothie for weight loss
For snacks, use special fruit mixtures containing fiber, proteins, vitamins and other ingredients. Such mixtures are commercially available, or you can prepare smoothies yourself.
Strawberry-oat smoothie
This is an appetizing and very tasty cocktail with strawberry flavor that just melts in your mouth. The very process of consuming it already brings incredible pleasure. And positive emotions for health and weight loss are as important as dietary nutrition.
Ingredients:
- low fat milk - 250 milliliters;
- oatmeal - 45 grams (this is 4 tablespoons of flakes without a slide);
- ripe banana - 1 banana;
- fresh or frozen strawberries - 10 pieces;
- vanilla extract - 1/2 teaspoon;
- natural honey - 1.5 teaspoons.
Preparation:
- Mix chopped banana, strawberries, rolled oats and milk in a blender.
- Add vanillin and a little honey if desired.
- Mix all the ingredients in a blender until we get a homogeneous mass.
Pour the finished smoothie into glasses, garnish with fresh mint leaves and serve.
Banana-oat smoothie for weight loss
To give your body the desired definition and get rid of extra pounds, prepare a delicious, healthy banana-oat smoothie. A very tasty and healthy drink that will give you a lot of pleasure with its unique delicate taste and pleasant aroma. To prepare it we will need:
- low-fat yogurt and skim milk - 120 milliliters each;
- one ripe banana;
- honey - 2 teaspoons;
- rolled oats - 3 tbsp. spoons;
- ground cinnamon - ¼ teaspoon.
It is recommended to make and consume this cocktail after physical activity, sports or training.
Preparation:
- Peel the banana and cut it into cubes, then place them in a blender bowl.
- Add milk, yogurt, oatmeal, honey and cinnamon to a blender.
- Mix all ingredients until smooth.
After preparing the smoothie, you need to immediately serve it to the table and eat it with pleasure and pleasure.
Fat burning cherry oat smoothie
This delicious cocktail with a slight sourness will give a pleasant aroma and quench your thirst in the heat.
Ingredients:
- pitted cherries - 200 grams;
- chopped oatmeal - 3 tbsp. spoons;
- banana, frozen or fresh with ice - 1 piece;
- water - 250 milliliters;
- natural honey - 1 tbsp. spoon;
- cinnamon - 1 teaspoon;
- nutmeg - ½ teaspoon.
Preparation:
- Place cherries, chopped banana and oatmeal into a blender bowl;
- Fill it all with water, add honey, cinnamon powder and nutmeg.
- Beat everything well with a blender until smooth.
Pour the breakfast preparations into glasses, decorate with cherries on top and sprinkle with a little cinnamon. Happy smoothie eating!
"L-thyroxine"
This drug is widely used for metabolic disorders in the body. The drug contains hormones. Metabolism is restored due to the normalization of thyroid function. The main active ingredient is sodium levothyroxine. The medication is available in the form of tablets (dosage 50 and 100 mg).
The drug can be prescribed by a specialist for diseases such as hypothyroidism, obesity, diffuse toxic goiter. Counting on the action of the main component, many overweight girls decide to carry out therapy using this medicine on their own. As a result, side effects develop. As the dosage increases, appetite may increase. In this case, the patient gets the opposite result - body weight begins to increase rapidly.
L-thyroxine should absolutely not be used by people suffering from epilepsy, serious disorders of the cardiovascular system, or kidney and liver failure.
If there are no contraindications, the tablets should be taken half an hour before meals with a sufficient amount of water. The initial dosage is 25 mg.
Phase 1 metabolism[edit | edit code]
The most common phase 1 metabolic pathway is oxidation. Reduction and hydrolysis also play an important role, but are less common.
Oxidation[edit | edit code]
Cytochromes P-450 (Table 4.4) are a superfamily that includes isoforms of hemoprotein enzymes that catalyze the oxidative metabolism of many xenobiotics (drugs and other exogenous chemicals).
The process of oxidation of a substance includes the stages of oxidation and reduction (Fig. 4.8). The sites of oxidation vary significantly; their common physical property is high solubility in lipids.
In most cases, drug oxidation is catalyzed by cytochromes P-450, although other enzymes also participate in this process, but to a lesser extent. There are several hundred cytochrome P-450 isoforms. Some of them are constitutive (i.e., always present), others begin to be synthesized only in response to appropriate stimuli - usually exogenous chemicals. Substrate specificity is a function of the cytochrome P-450 isoform and is usually relative rather than absolute, so the absence of any particular cytochrome P-450 isoform does not stop a given metabolic reaction. Genes of the cytochrome P-450 superfamily are mapped on several chromosomes.
Table 4.4 Examples of cytochrome P-450 families and isoforms that play an important role in oxidative metabolism | ||
Family | Isoform | Drug-substrate |
CYP1 | CYP1A2 | Theophylline |
CYP2 | CYP2D6 | Codeine |
CYP3 | CYP3A4 | Cyclosporine |
Rice.
4.8 Fig. 4.8 Mechanisms of drug oxidation by a mixed-function oxidase system. The drug binds to the oxidized form of a specific isoform of cytochrome P-450. This complex then receives one electron from NADPH via cytochrome P-450 reductase. The reduced complex then reacts with molecular oxygen (02) and a second electron is transferred via either NADPH and cytochrome P-450 reductase or NADP and cytochrome b5 reductase. In this process, one oxygen atom is released into the water and another is incorporated into the drug to form a hydroxylated metabolite. This metabolic reaction also applies to dealkylation reactions, where short-chain alkyl groups (usually methyl) are removed from a drug and combine with oxygen to form an aldehyde, which can then be oxidized or reduced. NADP - nicotinamide adenine dinucleotide phosphate.
Nomenclature for the cytochrome P-450 superfamily has been developed
:
- CYP: capital letters indicate that the isoform is of human origin;
- CYPx: x is an Arabic numeral indicating the isoform family;
- CYPxX: second capital letter indicates subfamily;
- CYPxXx: The last Arabic numeral indicates the product of an individual gene of the subfamily.
Family and subfamily status designations refer to the degree of amino acid sequence homology between different P-450 isoforms. For example, the designation CYP1A2 stands for: the human cytochrome P-450 isoform, belonging to the first family, is a member of the A subfamily of enzymes and is the product of the second gene of this subfamily.
Three families of cytochrome P-450s play important roles in the metabolism of a wide range of drugs
Three cytochrome P-450 families that are essential for drug metabolism are presented in Table. 4.4. The CYP3A subfamily has been identified as the major constitutive form in the human liver, and its isoforms catalyze the metabolism of a wide variety of drugs. This subfamily is expressed in significant numbers in other tissues. The specific isoform CYP3A4 is responsible for the intestinal metabolism (presystemic elimination) of many drugs with poor bioavailability.
The CYP2D6 isoform is associated with the following processes:
- oxidative metabolism of many drugs, including β-adrenergic receptor antagonists;
- demethylation of tricyclic antidepressants;
- demethylation of codeine to morphine. Approximately 5-10% of Caucasians are deficient in the phenotypic expression of CYP2D6 as an autosomal recessive trait. Multiple mutations of CYP2D6 have been described. Thus, the inability to demethylate codeine into morphine is associated with a lack of analgesic response to codeine.
CYP2E1 is a short-lived isoform induced by chronic alcohol consumption. CYP1A2 plays an important role in the metabolism of theophylline and is induced by flavonoids and polycyclic aromatic hydrocarbons found in some foods, so knowledge of a patient's metabolic constitution has potential predictive value in determining whether a particular drug will be appropriate. It can be expected that tests for the phenotypic expression of drug metabolizing enzymes will be available in the near future. Such information will help decide which specific drugs or classes of drugs can be used without complications associated with oxidation. However, caution is required in interpreting the phenotypic expression of gene products, because it can be modulated by environmental influences and physiological factors.
Cytochrome P-450 enzymes require the presence of mixed-function oxidases
For the functioning of cytochrome P-450, molecular oxygen, NADPH reductase of cytochrome P-450 and NADPH are required. This combination is called a mixed-function oxidase system. Cytochrome P-450 isoforms are present in this system in significant excess compared to cytochrome P-450 reductase, an enzyme that promotes the reduction process as the equivalent of an oxidative reaction. The process of oxidation of drug substrates by cytochromes P-450 is depicted in Fig. 4.8.
Table 4.5 Examples of drugs and prodrugs and their clinically important active metabolites
Medicine | Active metabolite |
Aplopurinol | Oxypurinol |
Diazepam | Desmethyldiazepam |
Imipramine | Desmethyl imipramine |
Morphine | Morphine-6-glucuronide |
Minoxidil | Minoxidil sulfate |
Procainamide | N-acetyl procainamide |
Prodrug | Active metabolite |
Codeine | Morphine |
Prednisone | Prednisolone |
Sulindak | Sulindac sulfide |
Oxidation usually results in drug inactivation, but prodrugs are an exception
Prodrugs are chemical agents that are metabolized into pharmacologically active substances, for example when codeine is demethylated to morphine (Table 4.5). Sometimes the oxidation of drugs leads to the formation of active metabolites whose duration of action exceeds that of the administered drug (for example, the conversion of diazepam to desmethyldiazepam).
When multiple drugs are administered simultaneously, they can interact with cytochrome P-450 isoforms, inhibiting each other's metabolism. As a result, prodrugs cannot be converted into active pharmacological products, and active substances are not able to be metabolized at the expected rate. As a result, there is no therapeutic effect or the substance has a toxic effect. Examples of medications are listed in table. 4.6.
Recovery[edit | edit code]
This metabolic reaction occurs in the presence of sensitive functional groups (eg nitro-, keto- or sulfoxide). The reduction process results in the activation or inactivation of drugs. For example:
- Sulindac is a prodrug whose sulfoxide group is reduced to form sulindac sulfide. This metabolite is an active cyclooxygenase inhibitor responsible for the anti-inflammatory effect of sulindac;
- prednisone is a prodrug whose keto group is reduced to a hydroxyl group; is an active glucocorticosteroid that is converted to prednisolone.
Hydrolysis[edit | edit code]
Hydrolysis can occur spontaneously due to instability of substituent groups in the drug.
Esters are especially susceptible to hydrolysis to form the parent acid and alcohol. Many types of different esterase enzymes are found in the body. Plasma esterases play an important role in the breakdown of many ester drugs. Spontaneous hydrolysis in the absence of enzymes has been described for acetylsalicylic acid (aspirin), which hydrolyzes in the presence of moisture to form salicylic acid. Some prodrugs are hydrolyzed after oral administration. For example:
- sulfasalazine is hydrolyzed to form aminosalicylic acid and sulfapyridine under the influence of bacterial flora of the lower gastrointestinal tract. These hydrolysis products are believed to be responsible for the pharmacological effects of sulfasalazine;
- Bambuterol (the carbamate ester of the prodrug terbutaline) is concentrated in lung tissue, where it is hydrolyzed by pseudocholinesterase to terbutaline, an active β2-adrenergic receptor agonist.
Make friends with aromatherapy and become an optimist
Essential oil from juniper is good for muscle pain, promotes vasodilation and thereby helps speed up metabolic processes. Combine business with pleasure - just inhale this smell or add it to a massage cream. Avoid stressful situations - because of them, fatty acids are released, redistributed throughout the circulatory system and deposited in the form of fat deposits. Learn different ways to relax after a hard day - do meditation, yoga or something like that, acquire a philosophical outlook on life. If these tips on how to speed up your metabolism aren't enough for you, here's another one for you: have sex more often - it's one of the best fat burners!
Phase 2 metabolism[edit | edit code]
Conjugation is the enzymatic addition of chemical radicals to a drug molecule or to a metabolite formed during phase 1
Phase 2 reactions, called conjugation, occur in a wide variety of tissues. Most often, these reactions involve the enzyme-mediated addition of hydrophilic moieties such as glucuronic acid, sulfate, glutathione and acetate to a functional group of the parent molecule and/or metabolite formed during phase 1. Glucuronic acid is first activated by combining with uridine diphosphate (UDP) . The activated compound UDP-glucuronic acid is then transferred to the drug by the enzyme glucuronosyltransferase. The resulting conjugates from such reactions are typically more hydrophilic than the parent drug or its phase 1 metabolites, so they are more easily excreted by the kidneys. In general, conjugates are pharmacologically less active than the parent drug, but not always (see below). Sometimes conjugation reactions involve substituent groups such as glycine, methyl groups, and the sugars glucose and ribose. Examples of clinically significant conjugation reactions are shown in Fig. 4.9; glucuronide conjugates are quantitatively the most significant.
Table 4.6 Examples of drugs and specific isoforms of cytochrome P-450 for correction to prevent metabolic interactions
Cytochrome P-450 isoform | Inhibiting drug | Major drugs whose activity is altered by inhibition |
CYP1A2 | Fluvoxamine | Clozapine Haloperidol |
Cimetidine | Clozapine Propranolol Theophylline | |
CYP2D6 | Amiodarone | Amitriptyline |
Fluoxetine | Codeine | |
Cimetidine | Flecainide | |
Quinidine | Propranolol | |
Paroxetine | Thioridazine | |
CYP3A4 | Cimetidine | Amiodarone |
Erythromycin | Astemizole | |
Fluconazole | Carbamazepine | |
Indinavir | Cyclosporine | |
Omeprazole | Diazepam | |
Sertraline | Fentanyl Simvastatin |
Conjugation generally increases water solubility, and acetylation results in the formation of metabolites that are less water soluble than the non-conjugated precursor (for example, in the case of acetylation of sulfonamide antibiotics). Acetylation of the basic amino group converts the base drug to a weak acid (amide). This chemical change affects the distribution and elimination of the resulting metabolite.
Conjugation reactions are usually thought of as an inactivation process, but there are a few exceptions (see Figure 4.9). For example:
- acetylation of the antiarrhythmic drug procainamide leads to the formation of N-acetylprocainamide, which also has antiarrhythmic properties, although it differs in the spectrum of ion channel blocking action from the parent drug;
- Morphine-6-glucuronide is an analgesic with a longer duration of action than its parent drug, morphine.
Impaired renal function affects the therapeutic and toxic effects of both metabolites.
Conjugation with sulfates may be an activation reaction. Minoxidil, an antihypertensive drug, must be sulfated at the N-oxide site to induce vasodilation effects. Minoxidil also promotes hair growth, but to a lesser extent than its sulfated metabolite, so the observed variations in hair growth may be due in part to the body's varying ability to sulfate minoxidil in the hair follicles.
Multiple isoforms of conjugating enzymes have been discovered and their relative specificity for various substrates and metabolites has been determined. At least 2 families and 3 subfamilies of glucuronosyltransferases have been described, as well as the products of many genes that perform acetylation and sulfation functions.
The dose of isoniazid, procainamide and hydralazine depends on the body's ability to acetylate these drugs. The higher the rate of acetylation, the higher the dose required to maintain therapeutic plasma concentrations of the drug. Phenotypically slow acetylators can become fast acetylators if certain drugs are taken orally with ethanol. This occurs if patients taking procainamide or sulfamethazine also drink alcohol.
Deficiency of one or more isoforms of conjugating enzymes may affect drug selection. In this regard, determining the body’s ability to metabolize prototypical substrates makes it possible to select drug therapy for a specific patient. Two clinically relevant examples can be given:
- patients with cancer and with thiopurine methyltransferase deficiency need to reduce the dose of 6-mercaptopurine by 10-15 times to reduce the risk of toxic effects of the drug on hematopoiesis;
Rice.
4.9 Examples of conjugation with the formation of active drug metabolites. Metabolism of drugs
- Most drugs are metabolized before being eliminated from the body
- Drug metabolites are generally more polar than the parent (parent) drugs
- The specificity of drug metabolizing enzymes is relative, not absolute.
- The content of drug metabolizing enzymes varies in different tissues
- Simultaneous ingestion of several drugs may affect the metabolic rate of one or more of them