Phenytoin: Mechanism of Action and Adverse Effects

Phenytoin is a medication used to manage seizures. Its mechanism of action involves binding to sodium channels, which increases their refractory period. However, the drug is associated with a large number of adverse effects, which can be categorized as acute, chronic, idiosyncratic, and teratogenic. Acute effects include dizziness, diplopia, nystagmus, slurred speech, ataxia, confusion, and seizures. Chronic effects include gingival hyperplasia, hirsutism, coarsening of facial features, drowsiness, megaloblastic anemia, peripheral neuropathy, enhanced vitamin D metabolism causing osteomalacia, lymphadenopathy, and dyskinesia. Idiosyncratic effects include fever, rashes, hepatitis, Dupuytren’s contracture, aplastic anemia, and drug-induced lupus. Teratogenic effects are associated with cleft palate and congenital heart disease. Although routine monitoring of phenytoin levels is not necessary, trough levels should be checked before dosing in cases of dose adjustment, suspected toxicity, or non-adherence to the prescribed medication.

The breakthrough dose should be 10 mg, which is one-sixth of the total daily morphine dose of 60 mg (30 mg taken twice a day).

Palliative care prescribing for pain is guided by NICE and SIGN guidelines. NICE recommends starting treatment with regular oral modified-release or immediate-release morphine, with immediate-release morphine for breakthrough pain. Laxatives should be prescribed for all patients initiating strong opioids, and antiemetics should be offered if nausea persists. Drowsiness is usually transient, but if it persists, the dose should be adjusted. SIGN advises that the breakthrough dose of morphine is one-sixth the daily dose, and all patients receiving opioids should be prescribed a laxative. Opioids should be used with caution in patients with chronic kidney disease, and oxycodone is preferred to morphine in patients with mild-moderate renal impairment. Metastatic bone pain may respond to strong opioids, bisphosphonates, or radiotherapy, and all patients should be considered for referral to a clinical oncologist for further treatment. When increasing the dose of opioids, the next dose should be increased by 30-50%. Conversion factors between opioids are also provided. Opioid side-effects are usually transient, such as nausea and drowsiness, but constipation can persist. In addition to strong opioids, bisphosphonates, and radiotherapy, denosumab may be used to treat metastatic bone pain.

Overall, the guidelines recommend starting with regular oral morphine and adjusting the dose as needed. Laxatives should be prescribed to prevent constipation, and antiemetics may be needed for nausea. Opioids should be used with caution in patients with chronic kidney disease, and oxycodone is preferred in patients with mild-moderate renal impairment. Metastatic bone pain may respond to strong opioids, bisphosphonates, or radiotherapy, and referral to a clinical oncologist should be considered. Conversion factors between opioids are provided, and the next dose should be increased by 30-50% when adjusting the dose. Opioid side-effects are usually transient, but constipation can persist. Denosumab may also be used to treat metastatic bone pain.

While the first trimester poses a higher risk of teratogenic effects from warfarin, most healthcare providers would opt for low molecular weight heparin in such cases. Additionally, the possibility of peripartum hemorrhage and the difficulty in reversing the effects of warfarin in such a scenario should also be taken into account.

During pregnancy, the body undergoes changes that make it more prone to blood clots. This is known as a hypercoagulable state and is most common in the last trimester. The increase in factors VII, VIII, X, and fibrinogen, along with a decrease in protein S, contribute to this state. Additionally, the growing uterus can press on the inferior vena cava, leading to venous stasis in the legs.

When it comes to managing deep vein thrombosis (DVT) or pulmonary embolism (PE) during pregnancy, warfarin is not recommended due to its potential harm to the fetus. Instead, subcutaneous low-molecular-weight heparin is preferred over intravenous heparin as it has a lower risk of bleeding and thrombocytopenia. It is important for pregnant women to be aware of the signs and symptoms of DVT/PE, such as leg swelling, pain, and shortness of breath, and to seek medical attention promptly if they experience any of these symptoms.

A young patient has a small fibroadenoma <3 cm, which is highly suggestive on imaging. There is no increase in the risk of breast cancer, so a core-needle biopsy is not necessary. Watchful waiting is appropriate, and cryoablation may be used for larger fibroadenomas. Fine-needle aspiration is only necessary for larger lumps or in older patients. Understanding Breast Fibroadenoma Breast fibroadenoma is a type of breast mass that develops from a whole lobule. It is characterized by a mobile, firm, and smooth lump in the breast, which is often referred to as a breast mouse. Fibroadenoma accounts for about 12% of all breast masses and is more common in women under the age of 30. Fortunately, fibroadenomas are usually benign and do not increase the risk of developing breast cancer. In fact, over a two-year period, up to 30% of fibroadenomas may even get smaller on their own. However, if the lump is larger than 3 cm, surgical excision is typically recommended. In summary, breast fibroadenoma is a common type of breast mass that is usually benign and does not increase the risk of breast cancer. While it may cause concern for some women, it is important to remember that most fibroadenomas do not require treatment and may even resolve on their own.

Screening for Hepatocellular Carcinoma: Recommended Tests and Intervals

Regular screening for hepatocellular carcinoma (HCC) is recommended in high-risk patients. Abdominal ultrasound (US) is the primary screening tool, with 6-month intervals for follow-up if a lesion of < 1 cm is detected. If there is no growth over 1-2 years, routine 6-monthly surveillance can continue. Alpha-fetoprotein (AFP) levels may be used in conjunction with US, but are not reliable on their own. A triphasic contrast computed tomography (CT) scan is recommended every two years for high-suspicion cases. This article provides an overview of the recommended tests and intervals for HCC screening.

Experiencing fever above 38ºC and night sweats in the past 6 months is linked to a poor prognosis if at least one of these ‘B’ symptoms is present. While acute lymphoblastic leukemia has a worse prognosis in individuals of Afro-Caribbean descent, Hodgkin’s lymphoma does not typically present with bone marrow failure and is more common in children. Alcohol-induced pain may be present in some cases of Hodgkin’s lymphoma, but it does not indicate a poor prognosis. While female sex is not linked to a poor prognosis, some studies suggest that males may have a worse outcome. Asymmetrical lymphadenopathy is a characteristic of Hodgkin’s lymphoma but has not been associated with a worse prognosis.

Understanding Hodgkin’s Lymphoma: Histological Classification and Prognosis

Hodgkin’s lymphoma is a type of cancer that affects the lymphocytes and is characterized by the presence of Reed-Sternberg cells. It is most commonly seen in individuals in their third and seventh decades of life. The histological classification of Hodgkin’s lymphoma is based on the type of cells present and their frequency. The most common type is nodular sclerosing, which is more common in women and has a good prognosis. Mixed cellularity is the second most common type and is associated with a large number of Reed-Sternberg cells. Lymphocyte predominant is a rare type with the best prognosis, while lymphocyte depleted is the rarest and has the worst prognosis.

In addition to the histological classification, there are other factors that can affect the prognosis of Hodgkin’s lymphoma. The presence of B symptoms, such as weight loss, fever, and night sweats, is associated with a poor prognosis. Other factors identified in a 1998 NEJM paper include age over 45 years, stage IV disease, low hemoglobin levels, low lymphocyte count, male gender, low albumin levels, and high white blood cell count. Understanding the histological classification and prognosis of Hodgkin’s lymphoma can help guide treatment decisions and improve outcomes for patients.

Pulmonary fibrosis is a potential side effect of bleomycin, a cytotoxic antibiotic commonly prescribed for metastatic germ cell cancer, squamous cell carcinoma, and non-Hodgkin’s lymphoma. The severity of this adverse effect is directly proportional to the dosage administered.

Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin, degrade preformed DNA and can lead to lung fibrosis. Anthracyclines, such as doxorubicin, stabilize the DNA-topoisomerase II complex and inhibit DNA and RNA synthesis, but can also cause cardiomyopathy. Antimetabolites, like methotrexate, inhibit dihydrofolate reductase and thymidylate synthesis, leading to myelosuppression, mucositis, liver fibrosis, and lung fibrosis. Fluorouracil (5-FU) is a pyrimidine analogue that induces cell cycle arrest and apoptosis by blocking thymidylate synthase, but can also cause myelosuppression, mucositis, and dermatitis. Cytarabine is a pyrimidine antagonist that interferes with DNA synthesis specifically at the S-phase of the cell cycle and inhibits DNA polymerase, but can also cause myelosuppression and ataxia. Drugs that act on microtubules, like vincristine and vinblastine, inhibit the formation of microtubules and can cause peripheral neuropathy, paralytic ileus, and myelosuppression. Docetaxel prevents microtubule depolymerisation and disassembly, decreasing free tubulin, but can also cause neutropaenia. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I which prevents relaxation of supercoiled DNA, but can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin, cause cross-linking in DNA and can lead to ototoxicity, peripheral neuropathy, and hypomagnesaemia. Hydroxyurea (hydroxycarbamide) inhibits ribonucleotide reductase, decreasing DNA synthesis, but can also cause myelosuppression.

Understanding Haemochromatosis: Symptoms, Causes, and Complications

Haemochromatosis is a genetic disorder that affects iron absorption and metabolism, leading to the accumulation of iron in the body. It is caused by mutations in the HFE gene on both copies of chromosome 6. This disorder is more common in people of European descent, with a prevalence of 1 in 200.

In the early stages of haemochromatosis, symptoms are often non-specific, such as fatigue and joint pain. As the disease progresses, patients may develop bronze skin pigmentation, diabetes mellitus, liver disease, cardiac failure, hypogonadism, and arthritis.

Treatment for haemochromatosis involves regular phlebotomy to remove excess iron from the body. Reversible complications of haemochromatosis include cardiomyopathy, skin pigmentation, liver cirrhosis, diabetes mellitus, hypogonadotrophic hypogonadism, and arthropathy. However, irreversible complications include cirrhosis, which can lead to liver failure and other serious health problems.

In conclusion, haemochromatosis is a genetic disorder that affects iron metabolism and can lead to serious health complications if left untreated. Early diagnosis and treatment can help prevent irreversible damage and improve quality of life for affected individuals.

This man is suffering from microcytic anemia, which is typically caused by a lack of iron. It is important to note that he was unwell when his blood was taken, as inflammation can cause ferritin levels to rise and potentially mask true iron deficiency. Therefore, additional iron studies are necessary to confirm the diagnosis. While thalassemia can also lead to microcytic anemia, his previous blood test showed no abnormalities.

Microcytic Anaemia: Causes and Considerations

Microcytic anaemia is a condition characterized by small red blood cells and low haemoglobin levels. There are several possible causes of microcytic anaemia, including iron-deficiency anaemia, thalassaemia, congenital sideroblastic anaemia, and lead poisoning. It is important to note that while anaemia of chronic disease can also present with microcytosis, it typically appears as a normocytic, normochromic picture.

In some cases, a normal haemoglobin level may be observed alongside microcytosis. This can be a red flag for polycythaemia rubra vera, which can cause iron-deficiency secondary to bleeding. Additionally, new onset microcytic anaemia in elderly patients should be investigated promptly to rule out underlying malignancy. It is worth noting that in beta-thalassaemia minor, the microcytosis may be disproportionate to the anaemia.

Overall, understanding the potential causes and considerations of microcytic anaemia is crucial for proper diagnosis and treatment.

Lynch syndrome is a genetic condition that increases the risk of developing colorectal cancer by over 80%. It also raises the risk of other cancers such as endometrial, stomach, breast, ovarian, small bowel, pancreatic, prostate, urinary tract, kidney, and liver cancer. Genetic testing is recommended for anyone diagnosed with colorectal cancer, regardless of age.

Breast cancer (BRCA) mutations are inherited in an autosomal dominant pattern and significantly increase the risk of developing breast, ovarian, prostate, and pancreatic cancer. These cancers tend to occur at a younger age than in the general population. While there is a possible link to colorectal pathology, other genetic syndromes should be considered first when looking for a genetic cause of cancer.

Cowden syndrome is a rare genetic condition characterized by benign growths called hamartomas on various parts of the body. It increases the risk of developing breast, thyroid, or endometrial cancer but has no association with colorectal cancer.

Familial adenomatous polyposis is an autosomal dominant condition that causes widespread colorectal adenomas, with polyps usually developing in late childhood. This greatly increases the risk of colorectal cancer, and prophylactic colectomy is often performed. Screening is recommended for those with an affected first-degree relative or multiple polyps detected on colonoscopy.

Von Hippel-Landau (VHL) syndrome is an autosomal dominant condition that causes multiple benign tumors and cysts in various parts of the body, including the brain, spinal cord, eyes, adrenals, kidneys, and pancreas. It increases the risk of renal and pancreatic cancer but has no association with colorectal cancer.