BMA Concise Guide to Medicine & Drugs

GASTROINTESTINAL TRACT

The gastrointestinal tract, also known as the digestive or alimentary tract, is the pathway through which food passes as it is processed to enable the nutrients it contains to be absorbed for use by the body. It consists of the mouth, oesophagus, stomach, duodenum, small intestine, large intestine (including the colon and rectum), and anus. In addition, a number of other organs are involved in the digestion of food: the salivary glands in the mouth, the liver, pancreas, and gallbladder. These organs, together with the gastrointestinal tract, form the digestive system.

The digestive system breaks down the large, complex chemicals – proteins, carbohydrates, and fats – present in the food we eat into simpler molecules that can be used by the body (see also Nutrition).

The stomach holds food and passes it into the intestine. The lining of the stomach releases gastric juice that partly digests food. The stomach wall continuously produces thick mucus that forms a protective coating.

The duodenum is the tube that connects the stomach to the intestine. Its lining may be damaged by excess acid from the stomach.

The pancreas produces enzymes that digest proteins, fats, and carbohydrates into simpler substances; pancreatic juices neutralize the acidity of the food passing from the stomach.

The gallbladder stores bile, which is produced by the liver, and releases it into the duodenum. Bile assists the digestion of fats by reducing them to smaller units that are more easily acted upon by digestive enzymes.

The small intestine is a long tube in which food is broken down by digestive juices from the gallbladder and pancreas. The mucous lining of the small intestine consists of tiny, finger-like projections called villi that provide a large surface area through which the products of digestion are absorbed into the bloodstream.

The large intestine receives both undigested food and indigestible material from the small intestine. Water and mineral salts pass through the lining into the bloodstream.

When a sufficient mass of undigested material, together with some of the body’s waste products, has accumulated, it is expelled from the body as faeces.

MOVEMENT OF FOOD THROUGH THE GASTROINTESTINAL TRACT

Food is propelled through the gastrointestinal tract by rhythmic waves of muscular contraction called peristalsis.

Muscle contraction in the gastrointestinal tract is controlled by the autonomic nervous system and is therefore easily disrupted by drugs that either stimulate or inhibit the activity of the autonomic nervous system. Excessive peristaltic action may cause diarrhoea, and constipation may result from slowed peristalsis.

WHAT CAN GO WRONG

Inflammation of the lining of the stomach or intestine (gastroenteritis) is usually the result of an infection or parasitic infestation. Damage may also occur through the inappropriate production of digestive juices, leading to minor complaints like acidity and major disorders like peptic ulcers. The lining of the intestine can be damaged by abnormal functioning of the immune system (inflammatory bowel disease). The rectum and anus can become painful and irritated by damage to the lining, tears in the skin at the opening of the anus (anal fissure), or enlarged veins (haemorrhoids).

Constipation, diarrhoea, and irritable bowel syndrome are the most frequently experienced gastrointestinal complaints, and they usually occur when something disrupts the normal muscle contractions that propel food residue through the bowel.

WHY DRUGS ARE USED

Many drugs for gastrointestinal disorders are taken by mouth and act directly on the digestive tract without first entering the bloodstream. Such drugs include certain antibiotics and other drugs used to treat infestations. Some antacids for peptic ulcers and excess stomach acidity, and the bulk-forming agents for constipation and diarrhoea, also pass through the system unabsorbed.

However, for many disorders, drugs with a systemic effect are required, including anti-ulcer drugs, opioid antidiarrhoeal drugs, and some of the drugs for inflammatory bowel disease.

MAJOR DRUG GROUPS

· Antacids

· Anti-ulcer drugs

· Antidiarrhoeal drugs

· Drugs for irritable bowel syndrome

· Laxatives

· Drugs for inflammatory bowel disease

· Drugs for rectal and anal disorders

· Drug treatment for gallstones

· Drug treatment for pancreatic disorders

Antacids

Digestive juices in the stomach contain acid and enzymes that break down food before it passes into the intestine. The wall of the stomach is normally protected from the action of digestive acid by a layer of mucus that is constantly secreted by the stomach lining. Problems arise when the stomach lining is damaged or too much acid is produced and eats away at the mucous layer.

Excess acid that leads to discomfort, commonly referred to as indigestion, may result from anxiety, overeating or eating certain foods, coffee, alcohol, or smoking. Some drugs, notably aspirin and non-steroidal anti-inflammatory drugs, can irritate the stomach lining and even cause ulcers to develop.

Antacids are used to neutralize acid and thus relieve pain. They are simple chemical compounds that are mildly alkaline and some also act as chemical buffers. Their chalky taste is often disguised with flavourings.

WHY THEY ARE USED

Antacids may be needed when simple remedies (such as a change in diet or a glass of milk) fail to relieve indigestion. They are especially useful after a meal to neutralize the acid surge that sometimes occurs after a meal.

Doctors prescribe these drugs in order to relieve dyspepsia (pain in the chest or upper abdomen caused by or aggravated by acid) in disorders such as inflammation or ulceration of the oesophagus, stomach lining, and duodenum. Antacids usually relieve pain resulting from ulcers in the oesophagus, stomach, or duodenum within a few minutes. Regular treatment with antacids reduces the acidity of the stomach, thereby encouraging the healing of any ulcers that may have formed.

TYPES OF ANTACID

Aluminium compounds These drugs have a prolonged action and are widely used, especially for indigestion and dyspepsia. They may cause constipation, but this is often countered by combining this type of antacid with one containing magnesium. Aluminium compounds can interfere with the absorption of phosphate from the diet, causing muscle weakness and bone damage if taken in high doses over a long period. A high blood level of aluminium may build up in people with kidney failure, causing a dementia-like illness.

Magnesium compounds Like the aluminium compounds, these have a prolonged action. In large doses magnesium compounds can cause diarrhoea, and in people who have impaired kidney function, a high blood magnesium level may build up, causing weakness, lethargy, and drowsiness.

Sodium bicarbonate This antacid acts quickly, but its effect soon passes. It reacts with stomach acids to produce gas, which may cause bloating and belching. Sodium bicarbonate is not advised for people with heart or kidney disease, because it can lead to accumulation of water (oedema) in the legs and lungs or serious changes in the acid-base balance of the blood.

Combined preparations Antacids may be combined with other substances called alginates and antifoaming agents. Alginates are intended to float on the contents of the stomach and produce a neutralizing layer to subdue acid that can otherwise rise into the oesophagus, causing heartburn. Antifoaming agents are used to relieve flatulence. In some preparations, a local anaesthetic is combined with the antacid to relieve discomfort in oesophagitis. The value of these additives is dubious.

HOW THEY WORK

By neutralizing stomach acid, antacids prevent inflammation, relieve pain, and allow the mucous layer and lining to mend. When used in the treatment of ulcers, they prevent acid from attacking damaged stomach lining and so allow the ulcer to heal.

HOW THEY AFFECT YOU

If antacids are taken according to the instructions, they are usually effective in relieving abdominal discomfort caused by acid. The speed of action, dependent on the ability to neutralize acid, varies. Their duration of action also varies; the short-acting drugs may have to be taken quite frequently.

Although most antacids have few serious side effects when used only occasionally, some may cause diarrhoea, and others may cause constipation (see Types of antacid).

RISKS AND SPECIAL PRECAUTIONS

Antacids should not be taken to prevent abdominal pain on a regular basis except under medical supervision, as they may suppress the symptoms of stomach cancer. Your doctor is likely to want to arrange tests such as endoscopy or barium X-rays before prescribing long-term treatment.

Antacids can interfere with the absorption of other drugs. Therefore, if you are taking a prescription medicine, you should check with your doctor or pharmacist before taking an antacid.

COMMON DRUGS

Antacids Aluminium hydroxide, Calcium carbonate, Hydrotalcite, Magnesium carbonate, Magnesium hydroxide, Magnesium trisilicate, Sodium bicarbonate

Antifoaming agents Dimeticone, Simeticone

Other drugs Alginates

Anti-ulcer drugs

Normally, the linings of the oesophagus, stomach, and duodenum are protected from the irritant action of stomach acids or bile by a thin covering layer of mucus. If this is damaged, or if large amounts of stomach acid are formed, the underlying tissue may become eroded, causing a peptic ulcer (break in the gut lining). An ulcer often leads to abdominal pain, vomiting, and changes in appetite. The most common type of ulcer occurs just beyond the stomach, in the duodenum. The exact cause of peptic ulcers is not understood, but a number of risk factors have been identified, including heavy smoking, the regular use of aspirin or similar drugs, and family history. An organism found in almost all patients who have peptic ulcers, Helicobacter pylori, is believed to be the main causative agent.

The symptoms caused by ulcers may be relieved by an antacid, but healing is slow. The usual treatment is with an anti-ulcer drug, such as a proton pump inhibitor, bismuth, or sucralfate, although an H2 blocker may be used. The anti-ulcer drug is usually combined with antibiotics to eradicate Helicobacter pylori infection.

WHY THEY ARE USED

Anti-ulcer drugs are used to relieve symptoms and heal the ulcer. Untreated ulcers may erode blood vessel walls or perforate the stomach or duodenum.

Eradication of Helicobacter pylori by an antisecretory drug (such as a proton pump inhibitor) combined with two antibiotics (known as “triple therapy”), may provide a cure in one to two weeks. Surgery is reserved for complications such as obstruction, perforation, haemorrhage, and when there is a possibility of cancer.

HOW THEY WORK

Drugs protect ulcers from the action of stomach acid, allowing the tissue to heal. H2 blockers, misoprostol, and proton pump inhibitors reduce the amount of acid released; bismuth and sucralfate form a protective coating over the ulcer. Bismuth also has an antibacterial effect.

HOW THEY AFFECT YOU

These drugs begin to reduce pain in a few hours and usually allow the ulcer to heal in four to eight weeks. They produce few side effects, although H2 blockers such as cimetidine can cause confusion in the elderly. Bismuth may blacken the faeces and sucralfate may cause constipation; misoprostol, diarrhoea; and proton pump inhibitors, either constipation or diarrhoea. Triple therapy is given for one or two weeks. If Helicobacter pylori is eradicated, maintenance therapy should not be necessary. Sucralfate is usually prescribed for up to 12 weeks, and bismuth and misoprostol for four to eight weeks. Because they may mask symptoms of stomach cancer, H2 blockers and proton pump inhibitors are normally prescribed only when tests have ruled out this disorder.

COMMON DRUGS

Proton pump inhibitors Esomeprazole, Lansoprazole, Omeprazole, Pantoprazole, Rabeprazole

H2 blockers Cimetidine, Famotidine, Nizatidine, Ranitidine

Other drugs Antacids, Antibiotics, Carbenoxolone, Misoprostol, Sucralfate, Tripotassium dicitratobismuthate (bismuth chelate)

Antidiarrhoeal drugs

Diarrhoea is an increase in the fluidity and frequency of bowel movements. In some cases diarrhoea protects the body from harmful substances in the intestine by hastening their removal. The most common causes of diarrhoea are viral infection, food poisoning, and parasites. But it also occurs as a symptom of other illnesses. It can be a side effect of some drugs and may follow radiation therapy for cancer. Diarrhoea may also be caused by anxiety.

An attack of diarrhoea usually clears up quickly without medical attention. The best treatment is to abstain from food and to drink plenty of clear fluids. Rehydration solutions containing sugar as well as potassium and sodium salts are widely recommended for preventing dehydration and chemical imbalances, particularly in children. You should consult your doctor if the condition does not improve within 48 hours; the diarrhoea contains blood; severe abdominal pain and vomiting are present; you have just returned from a foreign country; or the diarrhoea occurs in a small child or an elderly person.

Severe diarrhoea can impair absorption of drugs, and anyone taking a prescribed drug should seek advice from a doctor or pharmacist. Women taking oral contraceptives may require additional contraceptives.

The main types of drugs used to relieve nonspecific diarrhoea are opioids, and bulk-forming and adsorbent agents. Antispasmodic drugs may also be used to relieve accompanying pain (see Drugs for irritable bowel syndrome).

WHY THEY ARE USED

An antidiarrhoeal drug may be prescribed to provide relief when simple remedies are not effective, and once it is certain the diarrhoea is neither infectious nor toxic.

Opioids are the most effective antidiarrhoeals. They are used when the diarrhoea is severe and debilitating. Bulking and adsorbent agents have a milder effect and are often used when it is necessary to regulate bowel action over a prolonged period (for example, in people with colostomies or ileostomies).

HOW THEY WORK

Opioids decrease the muscles’ propulsive activity so that faecal matter passes more slowly through the bowel.

Bulk-forming agents and adsorbents absorb water and irritants in the bowel, resulting in larger, firmer stools at less frequent intervals.

HOW THEY AFFECT YOU

Drugs that are used to treat diarrhoea reduce the urge to move the bowels. Opioids and antispasmodics may relieve abdominal pain. All antidiarrhoeals may cause constipation if used in excess.

RISKS AND SPECIAL PRECAUTIONS

Used in relatively low doses for a limited period of time, the opioid drugs are unlikely to produce adverse effects. However, these drugs are not recommended for acute diarrhoea in children and should be used with caution when diarrhoea is caused by an infection, since they may slow the elimination of microorganisms from the intestine. All antidiarrhoeals should be taken with plenty of water. It is important not to take a bulk-forming agent together with an opioid or antispasmodic drug, because a bulky mass could form and obstruct the bowel.

COMMON DRUGS

Antispasmodics Alverine, Atropine, Dicycloverine (dicyclomine), Hyoscine, Mebeverine, Peppermint oil, Propantheline

Opioids Codeine, Co-phenotrope, Loperamide, Morphine/diamorphine

Antibacterials Ciprofloxacin

Bulk-forming agents and adsorbents Ispaghula, Kaolin, Methylcellulose, Sterculia

Other drugs Aluminium hydroxide, Colestyramine

Drugs for irritable bowel syndrome

Irritable bowel syndrome is a common, often stress-related, condition in which the waves of muscular contraction that normally move the bowel contents smoothly through the intestines become strong and irregular. This disruption often causes pain, and may be associated with diarrhoea or constipation.

Symptoms are often relieved by adjusting the amount of fibre in the diet, but medication may also be needed. Bulk-forming agents may be given to regulate consistency of the bowel contents. If pain is severe, an antispasmodic drug may be given. These drugs are anticholinergics (see Drugs that act on the parasympathetic nervous system), which reduce the transmission of nerve signals to the bowel wall. Tricyclic antidepressants are sometimes used because their anticholinergic action has a calming effect on the bowel.

COMMON DRUGS

Antispasmodics Atropine, Dicycloverine (dicyclomine), Hyoscine, Mebeverine

Opioids Loperamide

Other drugs Peppermint oil

Laxatives

When your bowels do not move as frequently as usual and the faeces are hard and difficult to pass, you are suffering from constipation. The most common cause is lack of sufficient fibre in your diet; fibre supplies the bulk that makes the faeces soft and easy to pass. The simplest remedy is more fluid and a diet that contains plenty of foods that are high in fibre, but laxative drugs may also be used.

Ignoring the urge to defecate can also cause constipation, because the faeces become dry, hard to pass, and too small to stimulate the muscles that propel them through the intestine.

Certain drugs may be constipating: for example, opioid analgesics, tricyclic antidepressants, and antacids containing aluminium. Some diseases, such as hypothyroidism (an underactive thyroid gland) and scleroderma (a rare disorder of connective tissue characterized by the hardening of the skin), can also lead to constipation.

The onset of constipation in a middle-aged or elderly person may be an early symptom of bowel cancer. Consult your doctor about any persistent change in bowel habit.

TYPES OF LAXATIVE

Bulk-forming agents These are relatively slow-acting but are less likely than other laxatives to interfere with normal bowel action. If the constipation is accompanied by abdominal pain, take them only after consulting your doctor because there is a risk of intestinal obstruction.

Stimulant (contact) laxatives These laxatives are for occasional use when other treatments have failed or when rapid onset of action is needed. They should not normally be used for longer than a week at a time, because they can cause abdominal cramps and diarrhoea.

Softening agents These treatments are often used when hard faeces cause pain as the bowels are opened – especially after surgery, when straining must be avoided, or if you have haemorrhoids. Liquid paraffin was once used to relieve faecal impaction (blockage of the bowel by faeces) but, because of its side effects, it has largely been replaced by docusate sodium.

Osmotic laxatives Preparations that contain magnesium carbonate or citrate may be used to evacuate the bowel before surgery or investigative procedures. They are not normally used for the long-term relief of constipation, however, because they can cause chemical imbalances in the blood.

Lactulose is an alternative to bulk-forming laxatives for long-term treatment of chronic constipation. It may cause stomach cramps and flatulence but is usually well tolerated.

WHY THEY ARE USED

Since prolonged use is harmful, laxatives should be used for very short periods only. They may prevent pain and straining in people with either hernias or haemorrhoids. Doctors may prescribe them for the same reason after abdominal surgery or childbirth. Laxatives are also used to clear the bowel before investigative procedures such as colonoscopy. They may be prescribed for elderly or bedridden patients because lack of exercise can often lead to constipation.

HOW THEY WORK

Laxatives act on the large intestine by increasing the speed with which faecal matter passes through the bowel, or increasing its bulk and/or water content. Stimulants cause the bowel muscles to contract, increasing the speed at which faecal matter goes through the intestine. Bulk-forming laxatives absorb water in the bowel, thereby increasing the volume of faeces, making them softer and easier to pass. Lactulose also causes fluid to accumulate in the intestine. Osmotic laxatives act by keeping water in the bowel, and thereby make the bowel movements softer. This also increases the bulk of the faeces and enables them to be passed more easily. Lubricant liquid paraffin preparations make bowel movements softer and easier to pass without increasing their bulk. Prolonged use can interfere with the absorption of some essential vitamins.

RISKS AND SPECIAL PRECAUTIONS

Laxatives can cause diarrhoea if taken in overdose, and constipation if overused. The most serious risk of prolonged use of most laxatives is developing dependence on the laxative for normal bowel action. Use of a laxative should therefore be discontinued as soon as normal bowel movements have been re-established. Children should not be given laxatives except in special circumstances on the advice of a doctor.

COMMON DRUGS

Stimulant laxatives Bisacodyl, Dantron, Docusate, Glycerol, Senna, Sodium picosulfate

Bulk-forming agents Bran, Ispaghula, Methylcellulose, Sterculia

Softening agents Arachis oil, Liquid paraffin

Osmotic laxatives Lactulose, Macrogols, Magnesium citrate, Magnesium hydroxide, Magnesium sulphate, Sodium acid phosphate

Drugs for inflammatory bowel disease

Inflammatory bowel disease is the term used for disorders in which inflammation of the intestinal wall causes recurrent attacks of abdominal pain, general feelings of ill-health, and frequently diarrhoea, with blood and mucus present in the faeces. Loss of appetite and poor absorption of food may often result in weight loss.

There are two main types of inflammatory bowel disease: Crohn’s disease and ulcerative colitis. In Crohn’s disease (also called regional enteritis), any part of the digestive tract may become inflamed, although the small intestine is the most commonly affected site. In ulcerative colitis, it is the large intestine (colon) that becomes inflamed and ulcerated, often producing bloodstained diarrhoea.

The exact cause of these disorders is not known, although stress-related, dietary, infectious, and genetic factors may all be important.

Establishing a proper diet and a less stressful lifestyle may help to alleviate these conditions. Bed rest during attacks is also advisable. However, these simple measures alone do not usually relieve or prevent attacks, and drug treatment is often necessary.

Three types of drug are used to treat inflammatory bowel disease: corticosteroids, immunosuppressants, and aminosalicylate anti-inflammatory drugs such as sulfasalazine. Nutritional supplements (used especially for Crohn’s disease) and antidiarrhoeal drugs may also be used. Surgery to remove damaged areas of the intestine may be needed in severe cases. Newer drugs for inflammatory bowel disease include infliximab (a monoclonal antibody that modifies the action of the immune system).

WHY THEY ARE USED

Drugs cannot cure inflammatory bowel disease, but treatment is needed, not only to control symptoms, but also to prevent complications, especially severe anaemia and perforation of the intestinal wall. Aminosalicylates are used to treat acute attacks of ulcerative colitis and Crohn’s disease, and they may be continued as maintenance therapy. People who have severe bowel inflammation are usually prescribed a course of corticosteroids, particularly during a sudden flare-up. Once the disease is under control, an immunosuppressant drug may be prescribed to prevent a relapse.

HOW THEY WORK

Corticosteroids and sulfasalazine damp down the inflammatory process, allowing the damaged tissue to recover. They act in different ways to prevent migration of white blood cells into the bowel wall, which may be responsible in part for the inflammation of the bowel.

HOW THEY AFFECT YOU

Taken to treat attacks, these drugs relieve symptoms within a few days, and general health improves gradually over a period of a few weeks. Aminosalicylates usually provide long-term relief from the symptoms of inflammatory bowel disease.

Treatment with an immunosuppressant drug may take several months before the condition improves; and regular blood tests to monitor possible drug side effects are often required.

RISKS AND SPECIAL PRECAUTIONS

Immunosuppressant and corticosteroid drugs can cause serious adverse effects and are prescribed only when potential benefits outweigh the risks involved.

The side effects of corticosteroids can be reduced by the use of budesonide in a topical preparation (enema) that releases the drug at the site of inflammation.

It is important to continue taking these drugs as instructed because stopping them abruptly may cause a sudden flare-up of the disorder. Doctors usually supervise a gradual reduction in dosage when such drugs are stopped, even when they are given as a short course for an attack. Antidiarrhoeal drugs should not be taken on a routine basis because they may mask signs of deterioration or cause sudden bowel dilation or rupture.

HOW THEY ARE ADMINISTERED

Antidiarrhoeals are usually taken in the form of tablets, although mild ulcerative colitis in the last part of the large intestine may be treated with suppositories or an enema containing a corticosteroid or aminosalicylate.

COMMON DRUGS

Corticosteroids Budesonide, Hydrocortisone, Prednisolone

Immunosuppressants Azathioprine, Mercaptopurine, Methotrexate

Aminosalicylates Balsalazide, Mesalazine, Olsalazine, Sulfasalazine

Other drugs Colestyramine, Infliximab, Metronidazole

Drugs for rectal and anal disorders

The most common disorder of the rectum (the last part of the large intestine) and anus (the opening from the rectum) is haemorrhoids, commonly known as piles. They occur when haemorrhoidal veins become swollen or irritated, often due to prolonged local pressure such as that caused by a pregnancy or a job requiring long hours of sitting. Haemorrhoids may cause irritation and pain, especially on defecation, and are aggravated by constipation and straining during defecation. In some cases haemorrhoids may bleed, and occasionally clots form in the swollen veins, leading to severe pain, a condition called thrombosed haemorrhoids.

Other common disorders include anal fissure (painful cracks in the anus) and pruritus ani (itching around the anus). Anal disorders of all kinds occur less frequently in people who have soft, bulky stools.

A number of both over-the-counter and prescription-only preparations are available for the relief of such disorders.

WHY THEY ARE USED

Preparations for relief of haemorrhoids and anal discomfort fall into three main groups: creams or suppositories that act locally to relieve inflammation and irritation; glyceryl trinitrate ointment, which reduces pain by relieving anal pressure and increasing blood flow; and measures that relieve constipation, which contributes to the formation of, and discomfort from, haemorrhoids and anal fissures.

Locally acting treatments often contain a soothing agent with antiseptic, astringent, or vasoconstrictor properties. Such ingredients include zinc oxide, bismuth, hamamelis (witch hazel), and Peru balsam. Some of these also include a mild local anaesthetic such as lidocaine. In some cases a doctor may prescribe an ointment containing a corticosteroid to relieve inflammation around the anus (see Topical corticosteroids).

People who suffer from haemorrhoids or anal fissure are generally advised to include in their diets plenty of fluids and fibre-rich foods, such as fresh fruits, vegetables, and whole grain products, both to prevent constipation and to ease defecation. A mild bulk-forming or softening laxative may also be prescribed.

Neither of these treatments can shrink large haemorrhoids, although they may provide relief while anal fissures heal naturally. Severe, persistently painful haemorrhoids that continue to be troublesome in spite of these measures may need to be removed surgically or, more commonly, by banding. This is a procedure in which a small rubber band is applied tightly to a haemorrhoid, thereby blocking off its blood supply; the haemorrhoid will eventually wither away.

HOW THEY AFFECT YOU

The treatments described here usually relieve discomfort, especially during defecation. Most people experience no adverse effects, although preparations containing local anaesthetics may cause irritation or even a rash in the anal area. It is rare for ingredients in locally acting preparations to be absorbed into the body in sufficient quantities to cause generalized side effects.

The main risk is that self-treatment of haemorrhoids may delay diagnosis of bowel cancer. It is therefore always wise to consult your doctor if symptoms of haemorrhoids are present, especially if you have noticed bleeding from the rectum or a change in bowel habits.

COMMON DRUGS

Soothing and astringent agents Aluminium acetate, Bismuth, Peru balsam, Zinc oxide

Topical corticosteroids Hydrocortisone

Local anaesthetics

Laxatives

Other drugs Glyceryl trinitrate

Drug treatment for gallstones

The formation of gallstones is the most common disorder of the gallbladder, which is the storage and concentrating unit for bile, a digestive juice produced by the liver. During digestion, bile passes from the gallbladder via the bile duct into the small intestine, where it assists in the digestion of fats. Bile is composed of several ingredients, including bile acids, bile salts, and bile pigments. It also has a significant amount of cholesterol, which is dissolved in bile acid. If the amount of cholesterol in the bile increases, or if the amount of bile acid is reduced, a proportion of the cholesterol cannot remain dissolved, and under certain circumstances this excess accumulates in the gallbladder as gallstones.

Gallstones may be present in the gallbladder for years without causing symptoms. However, if they become lodged in the bile duct they cause pain and block the flow of bile. If the bile accumulates in the blood, it may cause an attack of jaundice, or the gallbladder may become infected and inflamed.

Drug treatment with ursodeoxycholic acid is only effective against stones made principally of cholesterol (some contain other substances), and even these take many months to dissolve. Therefore, surgery and ultrasound have become widely used, especially the use of laparoscopic (“keyhole”) surgery. Surgery and ultrasound treatments are always used to remove stones blocking the bile duct.

WHY THEY ARE USED

Even if you have not experienced any symptoms, once gallstones have been diagnosed your doctor may advise treatment because of the risk of blockage of the bile duct. Drug treatment is usually preferred to surgery for small cholesterol stones or when there is a possibility that surgery may be risky.

HOW THEY WORK

Ursodeoxycholic acid is a substance that is naturally present in bile. It acts on chemical processes in the liver to regulate the amount of cholesterol in the blood by controlling the amount that passes into the bile. Once the cholesterol level in the bile is reduced, the bile acids are able to start dissolving the stones in the gallbladder. To achieve maximum effect, ursodeoxycholic acid treatment usually needs to be accompanied by adherence to a low-cholesterol, high-fibre diet.

HOW THEY AFFECT YOU

Drug treatment may often take years to dissolve gallstones completely. You will not, therefore, feel any immediate benefit from the drug, but you may have some minor side effects, the most usual of which is diarrhoea. If this occurs, your doctor may adjust the dosage. The effect of drug treatment on the gallstones is usually monitored at regular intervals by means of ultrasound or X-ray examinations.

Even after successful treatment with drugs, gallstones often recur when the drug is stopped. In some cases drug treatment and dietary restrictions may be continued even after the gallstones have dissolved, to prevent a recurrence.

Although the drug reduces cholesterol in the gallbladder, it increases the level of cholesterol in the blood because it reduces its excretion in the bile. Doctors therefore prescribe it with caution to people who have atherosclerosis (fatty deposits in the blood vessels). The drug is not usually given to people who have liver disorders because it can interfere with normal liver function. Surgical or ultrasound treatment is used for those with liver problems.

COMMON DRUGS

Drugs for gallstones Ursodeoxycholic acid

Other drugs Colestyramine

Drug treatment for pancreatic disorders

The pancreas releases certain enzymes into the small intestine that are necessary for digestion of a range of foods. If the release of pancreatic enzymes is impaired (by chronic pancreatitis or cystic fibrosis, for example), enzyme replacement therapy may be necessary. Replacement of enzymes does not cure the underlying disorder, but it restores normal digestion. Pancreatic enzymes should be taken just before or with meals, and usually take effect immediately. Your doctor will probably advise you to eat a diet that is high in protein and carbohydrates and low in fat.

Pancreatin, the generic name for those preparations containing pancreatic enzymes, is extracted from pig pancreas. Treatment must be continued indefinitely as long as the pancreatic disorder persists.

COMMON DRUGS

Pancreatic enzymes Amylase, Lipase, Pancreatin, Protease