See also Antivenoms , Immunotherapy General information The Hymenoptera genus, one of the largest genera of insects, includes bees and wasps, sawflies and ants. The name comes from Greek words for a membrane (hymen) and a wing (pteron). Bee and wasp venoms The toxins in bee venom include apamin, which inhibits small-conductance calcium-dependent potassium channels, and melittin, which activates phospholipase A2 and causes pain; histamine and…

See also Antihistamines General information Hydroxyzine is a first-generation antihistamine, a piperazine derivative, with antimuscarinic and sedative properties. Organs and systems You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

See also Cytotoxic and immunosuppressant drugs General information Hydroxycarbamide (hydroxyurea) is used to treat a variety of cancers, myeloproliferative disorders, and sickle cell disease, and has been studied in patients with HIV infection [ ]. It inhibits ribonucleotide reductase and increases concentrations of iron nitrosyl hemoglobin, nitrite, and nitrate, suggesting in vivo metabolism of hydroxycarbamide to nitric oxide [ ]. Organs and systems Hematologic Concern about…

General information Hydroquinone has been used in skin bleaching formulations for the treatment of hyperpigmentation and can cause short- and mid-term reactions like exogenous ochronosis and leukoderma en confetti, irritant reactions, and allergic reactions [ ]. Long-term adverse reactions such as nephrotoxicity and carcinogenicity have only been demonstrated in animals. You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles…

General information Intolerable adverse reactions or inadequate analgesia occur in 10–15% of patients with chronic pain given continuous intrathecal morphine. Hydromorphone is a semisynthetic derivative of morphine used extensively in the management of cancer pain. It is more soluble than morphine, has a slightly shorter duration of action, and is about five times more potent when given systemically. Drug studies Observational studies In an open, single…

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See also Fluoride salts and derivatives General information Hydrofluoric acid is widely used in industrial settings, but also in domestic products, such as cleaning solutions and rust removers. On the other hand, it is one of the most corrosive inorganic acids because of its strong affinity for protein [ ]. You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles…

General information Hydrocodone is a semisynthetic narcotic analgesic and a cough suppressant, similar to codeine. It is metabolized to the O- and N-demethylated products, hydromorphone and norhydrocodone [ ]. Drug studies You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

General information Hydrazine sulfate has been claimed to be effective in the management of cancers [ , ] and has been promoted as an alternative cancer cure [ ]. However, double-blind, randomized, placebo-controlled studies have suggested no benefit from hydrazine [ ], and it is itself carcinogenic. Hydrazine can arise as a metabolite of drugs such as isoniazid [ ] and atazanavir [ ] and may…

General information Hydralazine is a direct vasodilator that acts on vascular smooth muscle to produce systemic vasodilatation. As a result there is baroreceptor-mediated activation of the sympathetic nervous system and the renin–angiotensin system. Vasodilators (as monotherapy) are associated acutely with flushing, headache, dizziness, reflex tachycardia, and palpitation. Chronic treatment can be complicated by fluid retention. Organs and systems Cardiovascular Aggravation of angina, presumably as a result…

General information Hycanthone is a derivative of lucanthone, but has less gastrointestinal and nervous system toxicity. It is effective against both Schistosoma hematobium and Schistosoma mansoni and is given as a single intramuscular injection in doses of 1.0–2.5 mg/kg [ , ]. However, it has largely been superseded in the treatment of schistosomiasis by more recent, less toxic compounds. The most common adverse reactions to hycanthone,…

General information Hyaluronidase is an enzyme that depolymerizes the mucopolysaccharide hyaluronic acid, which is a component of the mucoprotein ground substance or tissue cement and thus increases membrane permeability, reduces viscosity, and makes tissues more readily permeable [ ]. It is found in snake venoms [ , ] and in the venoms of Hymenoptera , such as honey bees and yellow jacket wasps [ ]. It…

General information Hyaluronic acid is a naturally occurring polysaccharide that is widely distributed in body tissues and intracellular fluids, including the aqueous and vitreous humour, synovial fluid, and in the ground substance that surrounds cells [ ]. It is a high-molecular weight substance originally developed for use as a vitreous replacement. Although 98% of the product consists of water, it is very viscoelastic. Uses Hyaluronic acid…

General information Cervical cancer is the second most common cause of cancer deaths in women worldwide and the number one cause in the developing world. It is almost invariably associated with HPV infection. HPV type 16 is found in about 50% of cervical cancers. About 70% of cervical cancers are associated with HPV types 16, 18, and 8 other HPV types. Types 18, 31, and 45…

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General information For a complete account of adverse reactions to estrogens, readers should consult the following monographs as well as this one: Diethylstilbestrol Estrogens Hormonal contraceptives—emergency contraception Hormonal contraceptives—oral Hormone replacement therapy—estrogens Hormone replacement therapy—estrogens + androgens. For a complete account of adverse reactions to progestogens, readers should consult the following monographs as well as this one: Hormonal contraceptives—intracervical and intravaginal Hormonal contraceptives—oral Hormonal contraceptives—progestogen implants…

General information For a complete account of adverse reactions to estrogens, readers should consult the following monographs as well as this one: Diethylstilbestrol Estrogens Hormonal contraceptives—emergency contraception Hormonal contraceptives—oral Hormone replacement therapy—estrogens + androgens Hormone replacement therapy—estrogens + progestogens. Estrogen replacement therapy was until recently widely recommended for the prevention of osteoporosis in middle-aged and older women [ ]. Long-term estrogen therapy also reduces the incidence…

General information For a complete account of adverse reactions to estrogens, readers should consult the following monographs as well as this one: Diethylstilbestrol Estrogens Hormonal contraceptives—emergency contraception Hormonal contraceptives—oral Hormone replacement therapy—estrogens Hormone replacement therapy—estrogens + progestogens. You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

General information For a complete account of adverse reactions to progestogens, readers should consult the following monographs as well as this one: Hormonal contraceptives—intracervical and intravaginal Hormonal contraceptives—oral Hormonal contraceptives—progesterone implants Hormone replacement therapy—estrogens + progestogens Medroxyprogesterone Progestogens. Injectable hormonal contraceptives, which are normally composed of long-acting esters of progestogens, have obvious practical advantages over oral products when user adherence is poor, for example in illiterate…

General information Hormonal formulations for implantation contain progestogens, including the following: levonorgestrel; etonogestrel; desogestrel; megestrol; norethisterone. For a complete account of adverse reactions to progestogens, readers are urged to consult the following monographs as well as this one: Hormonal contraceptives—progestogen injections Hormonal contraceptives—intracervical and intravaginal Hormonal contraceptives—oral Hormone replacement therapy—estrogens + progestogens Medroxyprogesterone Progestogens. Two implants that release levonorgestrel, the six-capsule Norplant and the two-rod Jadelle,…