General information Phytoestrogens are naturally occurring, polyphenolic, non-steroidal plant compounds that are structurally similar to 17β-estradiol and have estrogenic and/or antiestrogenic effects. These effects are mediated by binding to estrogen receptors, by alterations in the concentrations of endogenous estrogens, and by binding to or stimulation of the synthesis of sex hormone binding globulin. There are four main groups of phytoestrogens: isoflavonoids, flavonoids, stilbenes, and lignans […

See also Phenols General information Spermicides are produced in a variety of formulations, including gels, foams, creams, suppositories, pessaries, capsules, foaming tablets, and melting films. Spermicides are also used in conjunction with other methods, such as diaphragms, condoms, and sponges, but also with intrauterine contraceptive devices and methods based on fertility awareness [ ]. Contraceptive sponges are controversial: do they act by delivering spermicides or as…

General information Intrauterine contraceptive devices (IUCDs) have been reviewed [ , ]. Most are composed of bland synthetic materials or contain in addition a small amount of metallic copper. Others are designed to release either progesterone or a synthetic progestogen (for example levonorgestrel) [ , ]. IUCDs that release levonorgestrel are somewhat more effective than copper-containing devices, while those that release progesterone are less effective […

General information Photochemotherapy, which consists of oral (and sometimes topical) administration of psoralens (the furocoumarins 5-methoxypsoralen, 8-methoxypsoralen, and trioxysalen) plus long-wave ultraviolet radiation, known as PUVA, is a well-established effective treatment for psoriasis, which has also been used for vitiligo [ ], mycosis fungoides, alopecia areata, dyshidrotic eczema, atopic dermatitis, and certain other skin diseases. Guidelines for treatment have been recommended [ , ]. Bathwater delivery…

General information Sildenafil is a potent inhibitor of phosphodiesterase type V, and therefore of the breakdown of cyclic guanosine monophosphate (cGMP) in the corpora cavernosa. The increased concentration of cGMP leads to nitric oxide-mediated relaxation of the smooth muscle cells and vasodilatation in the corpus cavernosum, which is essential for normal erection. Thus, sildenafil increases the penile response to sexual stimulation and is effective in erectile…

General information Phosphodiesterase type IV is a major regulator of cyclic adenosine monophosphate metabolism in many cell types, including smooth muscle, proinflammatory calls, and immune cells [ ]. Inhibitors of phosphodiesterase type IV, such as apremilast, cilomilast, and roflumilast, inhibit the synthesis of tumor necrosis factor alpha in monocytes, monocyte-derived derived dendritic cells, and macrophages and inhibit CD4 + T cell proliferation and production of cytokines…

General information There is a range of bipyridines that are selective inhibitors of a specific isoenzyme of phosphodiesterase, F-III. These include amrinone (inamrinone), enoximone (fenoximone), milrinone, olprinone, pimobendan, sulmazole, and vesnarinone. Their clinical pharmacology has been reviewed [ ]. The pharmacology, clinical pharmacology, uses, therapeutic value and adverse effects of positive inotropic drugs other than digitalis have been reviewed [ ], as has the suggestion that…

General information Phosphatidylcholine and its derivatives form a class of phospholipids that are major components of biological membranes and pulmonary surfactant (dipalmitoyl phosphatidylcholine or lecithin). Phosphatidylcholine is an essential component of the very low-density lipoprotein (VLDL) complex that facilitates the transport of triacylglycerols out of the liver. Subcutaneous injections of phosphatidylcholine have been used for localized subcutaneous fat reduction on the face and body [ ].…

General information An oral solution of sodium phosphates (dibasic sodium phosphate + monobasic sodium phosphate) is used as a laxative for the relief of occasional constipation and is used as part of a bowel-cleansing regimen in preparing patients for surgery or colonoscopy. Sodium phosphates are considered to be potentially dangerous [ ], particularly because of their effects on electrolyte balance. The FDA has limited the container…

See also Antiepileptic drugs General information Phenytoin is the only widely used hydantoin and, unless otherwise specified, reactions discussed here refer to phenytoin. Other hydantoin derivatives include ethotoin, mephenytoin, and albutoin (all of which are obsolete), and fosphenytoin. The latter is a water-soluble prodrug that is rapidly hydrolysed to phenytoin after intravenous or intramuscular injection. It causes fewer adverse reactions near the injection site (pain, phlebitis,…

General information In the past, phenylpropanolamine was marketed extensively in over-the-counter products for a variety of indications, and dietary supplements were marketed with no premarket safety evaluation, at least by the Food and Drug Administration (FDA), since for dietary supplements that include an ingredient marketed in the USA before 15 October 1994 no FDA review is required. Because many of these products were promoted as foodstuffs,…

General information Phenylephrine is seldom given systemically but is still commonly used as a mydriatic for both diagnostic and therapeutic purposes. Ocular application of phenylephrine 10% in pledget form is used to produce hemostasis in laser-assisted in-situ keratomileusis (LASIK) surgery and other ophthalmic surgical procedures. Phenylephrine is in some countries available in a non-prescription concentration of 0.12% for use as an ocular decongestant. Phenylephrine (up to…

General information Phenylbutazone was originally a solubilizing agent for aminopyrine and was first used to treat rheumatoid arthritis and allied disorders in 1949. Phenylbutazone and its related compounds were used worldwide until the early 1980s when, following growing concern about their safety, Ciba-Geigy published its own international assessment on phenylbutazone (Butazolidine) and oxyphenbutazone (Tanderil), which summarized reports on 1182 deaths associated with them from their initial…

General information Phentolamine is a non-selective alpha-adrenoceptor antagonist. It is used to treat hypertensive crises attributable to the effects of noradrenaline, as in pheochromocytoma and during the interaction of monoamine oxidase inhibitors with amine-containing medicaments and foods [ ]. It is also used to reverse the effects of local anesthetics in which adrenaline has been used [ ] and when ischemia has occurred [ ]. It…

See also Anorectic drugs General information Despite the withdrawal of the fenfluramines, the appetite suppressants phendimetrazine and phentermine have remained in widespread use for the treatment of obesity. With phentermine, adverse reactions due to stimulation of the central nervous system are less than with dexamfetamine, although in one study withdrawal because of adverse reactions was as high as 16 of 177 patients (9%); 2 of 13…

General information Phenoxybenzamine is a non-selective irreversible alpha-adrenoceptor antagonist. It is given orally in total daily doses up to 60 mg for management of pheochromocytoma, and lower doses have been used to relieve bladder obstruction before surgery. The maximum effect may be delayed because of irregular absorption, and even after intravenous use it may not be attained for 1 hour. Some of the most severe reactions,…

See also Opioid receptor agonists General information Phenoperidine is a potent opioid analgesic often used in neuroleptanalgesia and as a respiratory depressant in ventilated patients. 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 Physical contraceptives—spermicides General information Phenol is a benzyl alcohol and a major oxidized metabolite of benzene that was introduced into medicine as an antiseptic [ ]. Although it can be prepared in an aqueous solution or in glycerine, it appears to be more effective when mixed in aqueous compounds. At a concentration of 0.2% it is bacteriostatic and at over 1% bactericidal [ ].…

See also Antiepileptic drugs ; Barbiturates ; Primidone General information Because it is cheap and of unquestioned efficacy, phenobarbital is still widely prescribed around the world, for both epilepsy [ ], including status epilepticus [ , ], and as an enzyme inducer in neonates with unconjugated hyperbilirubinemia [ , ]. However, in developed countries its use in epilepsy has fallen since the introduction of drugs that…

See also Anorectic drugs General information Phenmetrazine and phendimetrazine are central stimulants and indirect sympathomimetics related to dexamfetamine. Phendimetrazine is about 30% rapidly metabolized to phenmetrazine [ ]. Reported adverse reactions include glossitis, stomatitis, dry mouth, nausea, abdominal pain, cramps, constipation, difficulty in micturition, and headache. Because of adverse reactions and the risk of abuse it has been withdrawn in several countries. Organs and systems Cardiovascular…